132 results on '"Abarca K"'
Search Results
2. Regional lymphadenopathy in cat-scratch disease: ultrasonographic findings
- Author
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García, C. J., Varela, C., Abarca, K., Ferrés, M., Prado, P., and Vial, P. A.
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- 2000
- Full Text
- View/download PDF
3. Flea and ticks species from dogs in urban and rural areas in four districts in Chile
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Abarca, K, Gárate, D, López, J, and Acosta-Jamett, G
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dogs ,pulgas ,áreas urbanas y rurales ,fleas ,urban and rural areas ,garrapatas ,perros ,ticks - Abstract
Fleas and ticks frequently parasitise canines worldwide and their prevalence in dogs is influenced by many factors including climate and geography, among others. Different studies worldwide have shown no clear pattern of an urban or rural preference by different species of fleas and ticks infesting dogs. The aim of this study is to identify species of fleas and ticks present in urban and rural dogs from different ecoregions of Chile. A cross-sectional study was conducted in four urban-rural paired sites at four districts: Arica y Parinacota, Coquimbo, Metropolitana and Araucanía. A random and a convenience sampling of households in the urban and rural areas was carried out, collecting fleas and ticks from 112-114 dogs per locality. The frequency of fleas and ticks infestation between urban and rural areas was compared through Chi-square or Fisher's tests. A total of 921 dogs were examined, identifying four species of fleas (Ctenocephalides canis, Ctenocephalides felis, Pulex irritans and Echidnophaga gallinacea) and three species of ticks (Rhipicephalus sanguineus, Amblyomma tigrinum and Amblyomma triste). In general, a higher prevalence of dogs with fleas were observed in rural areas, being C. canis the most frequent species globally; there were significant variations in the distribution of different species according to district. R. sanguineus was the predominant tick in all the studied areas. Amblyomma species were found exclusively in rural areas; A. triste only in Arica y Parinacota and A. tigrinum in rural areas of Coquimbo and Araucanía districts. Pulgas y garrapatas parasitan frecuentemente a caninos y su prevalencia se asocia a diversos factores incluyendo clima y geografía, entre otros. Diversos estudios han mostrado que no existe una clara preferencia entre sitios urbanos o rurales para las especies de pulgas y garrapatas que infectan perros. El objetivo de este estudio fue identificar especies de pulgas y garrapatas presentes en perros de zonas urbanas y rurales de diferentes ecorregiones de Chile. Se realizó un muestreo transversal en áreas urbano-rural de cuatro regiones de Chile: Arica y Parinacota, Coquimbo, Metropolitana y La Araucanía. En ciudades se realizó un muestreo estratificado y en zonas rurales un muestreo por conveniencia para muestrear pulgas y garrapatas de 112-114 perros por localidad. Se comparó la prevalencia de infestación entre urbano y rural por región mediante pruebas de Chi-cuadrado o Fisher. En total 921 perros fueron examinados, identificándose cuatro especies de pulgas (Ctenocephalides canis, Ctenocephalides felis, Pulex irritans y Echidnophaga gallinacea) y tres especies de garrapatas (Rhipicephalus sanguineus, Amblyomma tigrinum y Amblyomma triste). En general, se detectó un mayor número de perros con pulgas en zonas rurales, siendo C. canis la especie más frecuente; por otro lado, se detectó una diferencia en la distribución de las especies de acuerdo con el área estudiada. R. sanguineus fue la garrapata predominante en todas las áreas de estudio. Garrapatas del género Amblyomma se detectaron exclusivamente en áreas rurales; encontrándose A. triste solo en Arica y Parinacota y A. tigrinum en áreas rurales de las regiones de Coquimbo y La Araucanía.
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- 2016
4. Flea and ticks species from dogs in urban and rural areas in four districts in Chile
- Author
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Abarca, K, primary, Gárate, D, additional, López, J, additional, and Acosta-Jamett, G, additional
- Published
- 2016
- Full Text
- View/download PDF
5. One Health in Practice: A Pilot Project for Integrated Care of Zoonotic Infections in Immunocompromised Children and Their Pets in Chile
- Author
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Peña, A., primary, Abarca, K., additional, Weitzel, T., additional, Gallegos, J., additional, Cerda, J., additional, García, P., additional, and López, J., additional
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- 2015
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6. IRF8 mutations and human dendritic-cell immunodeficiency
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Hambleton S, Salem S, Bustamante J, Bigley V, Boisson-Dupuis S, Azevedo J, Fortin A, Haniffa M, Ceron-Gutierrez L, Bacon CM, Menon G, Trouillet C, McDonald D, Carey P, Ginhoux F, Alsina L, Zumwalt TJ, Kong XF, Kumararatne D, Butler K, Hubeau M, Feinberg J, Al-Muhsen S, Cant A, Abel L, Chaussabel D, Doffinger R, Talesnik E, Grumach A, Duarte A, Abarca K, Moraes-Vasconcelos D, Burk D, Berghuis A, Geissmann F, Collin M, Casanova JL, and Gros P
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- 2011
7. Plan de marketing para R.H. Seguridad
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Abarca K., Constanza, Cifuentes C., Carolina, Bravo, María Paz, Facultad de Economía y Negocios, and Escuela de Ingeniería en Administración de Empresas
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Plan de Marketing ,Planificación de la Comercialización ,Chile ,Administración de Comercialización ,Empresas - Abstract
Tesis (Ingeniero en Administración de Empresas) R.H. Seguridad es una empresa fundada en Concepción y con oficinas también en Santiago. Sus dos socios aportan una gran experiencia en materias de seguridad y de administración de personal. Esta empresa ofrece servicios principalmente a empresas y organizaciones. La innovación tecnológica está presente en R.H. Seguridad, permitiendo a sus clientes, por ejemplo, no sólo el control a distancia de la seguridad, sino también, la operación de su empresa por su propia red o Internet. Es una empresa con una marcada orientación al cliente, asegurando así buenos resultados reflejados en el grado de satisfacción de sus clientes. El plan de marketing que se presentará a continuación, tiene como objetivo final lograr solución al problema que presenta esta empresa, es decir, aumentar la participación de mercado con la que cuenta actualmente RH Seguridad en Santiago.
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- 2009
8. [Complications in children with varicella in 4 hospitals in Santiago, Chile: clinical spectrum and estimation of direct costs]
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Abarca K, Hirsch T, Potin M, Perret C, Zamorano J, González C, and Pablo Vial
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Male ,Adolescent ,Infant, Newborn ,Infant ,Bacterial Infections ,Direct Service Costs ,Hospitalization ,Chickenpox ,Child, Preschool ,Humans ,Female ,Chile ,Child ,Retrospective Studies - Abstract
The knowledge of varicella complications and their associated cost may help for a better evaluation of varicella immunization benefits.To determine frequency, type, outcome and affected population of varicella complications in children requiring hospitalization, and to estimate their direct costs.Retrospective analysis of medical records of children admitted to four hospitals in Santiago, Chile, due to varicella complications between January 1997 and February 1999. Calculation of direct costs of hospitalizations in a sample of 30 patients.One hundred fifty four patients were identified, 74% were younger than 5 years old, only one was immunocompromised. Complications identified were skin and soft tissue infections in 63%, invasive infections in 25.3%, neurological in 7.1% and miscellaneous in 4.5%. Staphylococcus aureus and Group A beta-haemolytic Streptococcus (GABS) were predominantly isolated. S. aureus was the main agent identified in superficial infections and GABS in invasive infections (sterile sites). Two patients died due to invasive infections (streptococcal toxic shock and S. aureus septicaemia) and 11 required surgical procedures. The average cost per hospitalization was US$ 600 in public hospitals and US$ 1,800 in the private hospital.Varicella complications requiring hospitalization are due mainly to bacterial infections and they affect immunocompetent toddlers. These complications can be severe and even fatal.
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- 2001
9. One Health in Practice: A Pilot Project for Integrated Care of Zoonotic Infections in Immunocompromised Children and Their Pets in Chile.
- Author
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Peña, A., Abarca, K., Weitzel, T., Gallegos, J., Cerda, J., García, P., and López, J.
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IMMUNOCOMPROMISED patients , *ZOONOSES , *CHILDREN & animals , *DISEASE vectors , *PYRETHROIDS , *CAMPYLOBACTER jejuni , *TOXOCARIASIS , *PREVENTION , *DISEASE risk factors - Abstract
Although pets provide physiological and psychological benefits to their owners, they are a potential source of zoonotic infections, especially for vulnerable individuals such as immunocompromised patients. During 1 year, we therefore performed a pilot project, which included 32 immunocompromised Chilean children and their family pets (35 dogs and 9 cats) with the aim of detecting, treating and preventing zoonotic infections. Children were examined by Infectious Diseases paediatricians and demographical and clinical information related to zoonotic infections were recorded. Pets were examined and sampled by veterinarians, who also administered missing routine vaccines and anti-parasitics. During family visits, all members were informed and educated about zoonoses and a satisfaction survey was performed. Visits also included vector control and indoor residual spraying with pyrethroids. Children were re-examined and re-tested according to the findings of their pets, and all detected zoonotic infections were treated both in children and pets. Physical examination revealed abnormalities in 18 dogs (51.4%) and three cats (33.3%). Twenty-eight (63.6%) of the pets were diagnosed with a zoonotic pathogen, and seven (15.9%) with a facultative pathogen. Most zoonotic agents were isolated from the pet's external ear and intestine. Bacteria with the highest pathogenic potential were Campylobacter jejuni and Brucella canis. In two children and their respective pets, the same zoonotic diseases were diagnosed (toxocariasis and giardiasis). Arthropods serving as potential vectors of zoonotic infections were found in 49% of dogs and 44% of cats. The pilot project was positively evaluated by the participating families. Our pilot project confirmed that pets are reservoir for various zoonotic agents in Chile and that the implementation of an integrated multidisciplinary programme was a valuable tool to prevent, diagnose and treat such zoonotic infections in vulnerable patients such as immunocompromised children. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
10. [Bartonella henselae infection in immunocompetent patients: cat scratch disease]
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Abarca K, Pablo Vial, Rivera M, García C, Oddó D, Prado P, and Ferrés M
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Male ,Conjunctivitis, Bacterial ,Bartonella henselae ,Adolescent ,Cat-Scratch Disease ,Humans ,Female ,Child ,Immunocompetence ,Lymphatic Diseases - Abstract
Cat scratch disease, whose etiologic agent is Bartonella henselae, is a benign disease in immunocompetent subjects, characterized by lymphadenopathy of prolonged course and occasional involvement of other organs such as liver, spleen, central nervous system, eye and lung. In immunocompromised patients, the infection is bacteremic and disseminated.To report Chilean cases of cat scratch disease.Ten children (seven male, aged between 6 and 13 years old) with histologically or serologically confirmed cat scratch disease are reported.Lymphadenopathy location was pre auricular in four cases, axillary in two, inguinal in two and epitrochlear in two. Three children had fever over 39 degrees C and two had a parinaud syndrome. Nine children had a history of cat scratch and one of a cat byte. Six had an erythrocyte sedimentation rate over 40. Lymph node ultrasound examination was a useful diagnostic tool. Two patients had splenic granulomas. Lymph node biopsies were obtained in four cases, showing a suppurative granulomatous lymphadenitis in all and a positive Warthin-Starry stain in two. Serology, done in patients without histological confirmation was positive with titles ranging from 1:64 to 1:8192. All patients had a satisfactory outcome with regression of lymphadenopathy.Infections by Bartonella hemselae occur in the Chilean population and must be considered in the differential diagnosis of regional lymph node enlargement.
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- 1996
11. [Neuroborreliosis in Chile. Report of a child probably infected by imported pets]
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Abarca K, Ribera M, Prado P, Lobos T, Palacios O, Ferrés M, Mesa T, and Pablo Vial
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Male ,Lyme Disease ,Ticks ,Borrelia burgdorferi Group ,Cricetinae ,Animals ,Humans ,Arachnid Vectors ,Bites and Stings ,Child - Abstract
Lyme disease, caused by the spirochete Borrelia burgdorferi, has several clinical manifestations and is transmitted to man by tick bites. In Chile and Latin America, several cases have been reported, but none with immunoblot confirmation or isolation of the infecting organism. We report a 9 year old boy consulting with bilateral facial palsy, polyradiculoneuritis with tetraparesis and meningeal irritation. Cerebrospinal fluid analysis showed increased protein concentration without pleocytosis and negative viral or bacterial cultures. IgM antibodies against Borrelia burgdorferi, were positive by ELISA and were confirmed by immunoblot at the Reference Laboratory of the University of Connecticut. The child had a recent contact with hamsters brought from Germany. The substantiation of Lyme disease existence in Chile should prompt the search and isolation of the causal agent.
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- 1996
12. [Natural history of human immunodeficiency virus infection in a cohort of Chilean patients]
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Pablo Vial, Ferreccio C, Abarca K, Ortiz E, Noriega M, Pérez C, Labarca J, Torres M, Ferrés M, González C, and Acuña G
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Adult ,Diarrhea ,Male ,Acquired Immunodeficiency Syndrome ,Time Factors ,Virus Cultivation ,Adolescent ,Incidence ,Age Factors ,Sexually Transmitted Diseases ,HIV Infections ,Middle Aged ,CD4 Lymphocyte Count ,Cohort Studies ,Multivariate Analysis ,Disease Progression ,Humans ,Female ,Prospective Studies ,Chile - Abstract
We characterized clinical manifestations and the risk to develop AIDS in a cohort of 32 patients infected with human immunodeficiency virus without AIDS A multivariate analysis was performed to determine association between the progression of infection and control variables (socioeconomic level, age, sex and sexual preferences) and causal variables (psycho-social changes, significant clinical events, stress scoring and sexual activity). The cumulative AIDS incidence, defined as a CD4 lymphocyte count below 200 cells/cm3 was 50% at 6.5 years and 82% at 8 years. Using clinical criteria to define AIDS, 50% developed the disease at 8 years of follow up. Among studied factors, only age (faster progression at higher age) and time of evolution were associated with progression in stages before AIDS, the most frequent diseases were acute diarrhea, sexual transmission diseases, oral candidiasis, sinusitis and varicella zoster infections. The reduction; of CD4 lymphocytes-below 200 cells/cm3 always preceded the symptoms of the disease. Two patients have remained more than eight years without clinical or immunological deterioration.Clinical manifestations and the risk of developing AIDS were studied in a cohort of 32 HIV-seropositive patients referred by their treating physicians to the Center for Medical Investigation of the Catholic University of Chile. The only exclusion criteria were a CD4 lymphocyte count below 400 or marked symptoms of AIDS. The study design included an examination at entry and every 6 months thereafter for a maximum follow up of 3 years. A multivariate analysis was conducted to determine the relation between disease progression and control and causal variables. The subjects were 8 women averaging 38 years old and 24 men averaging 33 years. Most were middle class and had higher education. 46% of the men became sexually active before age 15 and 42% were homosexual. HIV transmission was sexual in 28 subjects, through intravenous drug use in 2, and by unknown route in 2. The subjects had been infected for an average of 4.3 years at entry into the study. Of the 30 whose date of infection was known, 16 developed AIDS during the study according to the criterion of CD4 lymphocyte count below 200, and 8 of these developed markers of AIDS. 50% of patients developed AIDS 6.5 years after infection and 82% 8 years after. Using clinical criteria, 50% of patients had developed AIDS 8 years after infection. Multivariate analysis showed only subject's age at infection (faster progression at higher ages) and length of time since infection to be related to the risk of developing AIDS. No association was observed between development of the disease and sex, sexual orientation, use of alcohol or drugs, smoking, history of sexually transmitted diseases, number of sexual partners, or frequency of sexual relations. The most frequently observed pathologies before the stage of AIDS were acute diarrhea, sexually transmitted diseases, oral candidiasis, sinusitis, and varicela zoster infections. In the patients who progressed to AIDS, the decline of the CD4 lymphocyte count below 200 always preceded other symptoms. Two patients showed no significant decline in CD4 lymphocyte count or clinical manifestations of AIDS more than 8 years after infection.
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- 1996
13. Clinical and epidemiology characterization of children hospitalized with influenza A H1N1 (FLU AH1N1) during the first wave of 2009 outbreak, Santiago, Chile
- Author
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Sandoval, C., primary, Vizcaya, C., additional, Perret, C., additional, Ferrés, M., additional, Martinez, C., additional, Godoy, P., additional, Ferrer, P., additional, Monge, M., additional, Abarca, K., additional, Castillo, A., additional, Potin, M., additional, and Lopez, J.C., additional
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- 2010
- Full Text
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14. KAWASAKI DISEASE. AN EXPERIENCE OF 15 YEARS. SANTIAGO OF CHILE
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Barr??a, Ra??l, primary, Abarca, K, additional, Stegmaier, Helen, additional, Heusser, F, additional, C??spedes, P, additional, and Talesnik, E, additional
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- 2006
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15. Endemic scrub typhus-like illness, Chile.
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Balcells ME, Rabagliati R, García P, Poggi H, Oddó D, Concha M, Abarca K, Jiang J, Kelly DJ, Richards AL, Fuerst PA, Balcells, M Elvira, Rabagliati, Ricardo, García, Patricia, Poggi, Helena, Oddó, David, Concha, Marcela, Abarca, Katia, Jiang, Ju, and Kelly, Daryl J
- Abstract
We report a case of scrub typhus in a 54-year-old man who was bitten by several terrestrial leeches during a trip to Chiloé Island in southern Chile in 2006. A molecular sample, identified as related to Orientia tsutsugamushi based on the sequence of the16S rRNA gene, was obtained from a biopsy specimen of the eschar on the patient's leg. Serologic analysis showed immunoglobulin G conversion against O. tsutsugamushi whole cell antigen. This case and its associated molecular analyses suggest that an Orientia-like agent is present in the Western Hemisphere that can produce scrub typhus-like illness. The molecular analysis suggests that the infectious agent is closely related, although not identical, to members of the Orientia sp. from Asia. [ABSTRACT FROM AUTHOR]
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- 2011
- Full Text
- View/download PDF
16. Regional lymphadenopathy in cat-scratch disease: ultrasonographic findings.
- Author
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Garcáa, C. J., Varela, C., Abarca, K., Ferrés, M., Prado, P., and Vial, P. A.
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GRAM-negative bacterial diseases ,ULTRASONIC imaging ,PATIENTS ,BARTONELLA ,PUBLIC health ,HODGKIN'S disease - Abstract
Background. Cat-scratch disease (CSD) is considered to be an emerging disease worldwide and is caused by Bartonella henselae, a gram-negative bacterium introduced by a scratch or bite of a cat. The most common clinical manifestation is regional lymphadenopathy, but clinical recognition may be difficult, as atypical manifestations may occur. The diagnosis is confirmed with serologic testing and histology is rarely needed. This paper is based on our experience with the use of ultrasonography in the diagnosis of CSD.¶Objective. The aim of this study was to describe the sonographic and color Doppler appearances of regional lymphadenopathy in CSD, as this has not widely reported in the literature. ¶Materials and methods. Forty-seven patients (average 9.4 years) were included who all had serologically and/or histologically proven CSD and had been studied using US early in the clinical course. All had a positive history of exposure to cats and exhibited regional lymphadenopathy.¶Results. US showed large hypoechoic adenopathy with some transmission enhancement and high vascularization on color-flow Doppler imaging. In 30 patients, abdominal US was also performed and splenic and/or hepatic granulomata were found in 10.¶Conclusions. In our experience, sonography and especially color-Doppler and power-Doppler sonography was helpful in the diagnosis of CSD. We believe it should be used in the initial study of children with regional lymphadenopathy, and serologic testing should be performed when CSD is suspected. [ABSTRACT FROM AUTHOR]
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- 2000
17. Efficacy of Hepatitis A Vaccination in Children Aged 12 to 24 Months
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Abarca, K., Ibanez, I., Flores, J., Vial, P. A., Safary, A., and Potin, M.
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- 2001
- Full Text
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18. Exome Sequencing Reveals Primary Immunodeficiencies in Children with Community-Acquired Pseudomonas aeruginosa Sepsis
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Asgari S, Pj, Mclaren, Peake J, Wong M, Wong R, Bartha I, Jr, Francis, Abarca K, Ka, Gelderman, Agyeman P, Aebi C, Berger C, Jacques Fellay, Lj, Schlapbach, and Swiss Pediatric Sepsis Study
19. [Molecular epidemiology of the human immunodeficiency virus type 1 in Santiago, Chile]
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Pérez C, Pablo Vial, Ks, Dorman, Wang G, Abarca K, Js, Sinsheimer, and Ah, Kaplan
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Adult ,Male ,Acquired Immunodeficiency Syndrome ,Base Sequence ,Molecular Sequence Data ,Middle Aged ,Polymerase Chain Reaction ,HIV Protease ,DNA, Viral ,HIV-1 ,Humans ,Female ,Amino Acid Sequence ,Chile - Abstract
Most of the studies of HIV-1 infection in South America have been limited to Brazil and little is known about the viral variants that are causing disease elsewhere in the continent.To determine the characteristics of the viral variants present in Chile as well as patterns of viral transmission.Viral sequences were obtained from 21 HIV-1 infected people from Santiago, Chile who were infected either via sexual contact or intravenous drug use. Cloned sequences obtained from both the third variable and conserved regions of the envelope as well as the viral protease were evaluated.We found only clade B subtype viruses in Santiago. An evaluation of the envelope gene revealed no evidence that the sequences were monophyletic by risk group. A number of the protease sequences were predicted to encode amino acid substitutions commonly found during selection for protease inhibitor resistance.The HIV-1 strains studied in Chile, belong to the subtype B. There is no molecular evidence of separate introductions of the virus into the different risk groups. A number of substitutions in the protease gene that may confer resistance to protease inhibitors were found in patients with no previous exposure to this class of drugs.
20. [Seroprevalence of cytomegalovirus and Toxoplasma gondii in healthy subjects under 30 years old in Santiago, Chile]
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Abarca K, Pablo Vial, Zamorano J, Paris C, Ferrés M, Villarroel L, and Ferreccio C
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Adult ,Male ,Chi-Square Distribution ,Adolescent ,Antibodies, Protozoan ,Cytomegalovirus ,Infant ,Antibodies, Viral ,Risk Factors ,Seroepidemiologic Studies ,Child, Preschool ,Cytomegalovirus Infections ,Prevalence ,Animals ,Humans ,Female ,Chile ,Child ,Toxoplasma ,Toxoplasmosis - Abstract
Infections by Cytomegalovirus and Toxoplasma gondii are endemic in Chile and only a low proportion of infected individuals have clinical manifestations.To study the prevalence of infection by Cytomegalovirus and Toxoplasma gondii in Chile.The prevalence of IgG antibodies against Cytomegalovirus and Toxoplasma gondii were studied in 560 subjects under 30 years old, using an ELISA technique. Age, socioeconomic level, breast feeding, assistance to nurseries and number of family members were considered as risk factors for these infections.Infection by Cytomegalovirus had a global prevalence of 60%. It showed an epidemiological pattern of late acquisition in high socioeconomic levels and a pattern of early infection in medium and low socioeconomic levels. Eighty to 90% of sera were positive for the infection in adult subjects of the three socioeconomic levels. There was a positive correlation between the duration of breast feeding and the frequency of Cytomegalovirus infection. Infection by Toxoplasma gondii had a global prevalence of 24.6%. The rates of susceptible individuals were 80 and 50% in high and medium-low socioeconomic levels respectively.The knowledge about the frequency of these infections in high risk populations such as women during their reproductive years and immunodepressed individuals, will allow the implementation of preventive measures.
21. [Resistance of human immunodeficiency virus (HIV) to zidovudine. Genotypic analysis in strains isolated from Chilean patients]
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Pablo Vial, Vial C, Abarca K, Noriega M, Jiménez G, Labarca J, Gasep J, Palacios O, Pérez C, and Acuña G
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Genotype ,Anti-HIV Agents ,Mutation ,Drug Resistance ,HIV ,Humans ,HIV Infections ,Prospective Studies ,Chile ,Codon ,Zidovudine ,Follow-Up Studies - Abstract
Resistance of HIV to AZT is the result of mutations in the pol gene that codifies the enzyme reverse transcriptase.To assess the resistance to antiretroviral drugs in Chilean patients infected with HIV.The presence of mutations was searched in 22 patients infected with HIV. The emergence or persistence of these mutations was studied in sequential samples of 19 patients. The presence of the mutation that confers resistance to didanosine (DDI) was studied in those subjects exposed to the drug. Polymerase chain reaction techniques were used to analyze mutations in codons 41, 70 and 215 of the pol gene (resistance to AZT) and the mutation in codon 71 (resistance to DDI).On admission, none of the patients without previous exposure to AZT had drug resistance mutations. Seven of 12 patients (58.3%) that had received AZT had mutations in codon 215. In two, they were associated to a mutation in codon 41 and in two, a mutation in codon 70. After a mean follow up of 14 months, 13 of 15 patients (86%) that received AZT had viral strains genotypically resistant to the drug. In nine of these, the resistance was associated with disease progression. None of the 10 patients that received DDI had the mutation in codon 74 that confers resistance to the drug. However, in one of these patients, that never received AZT, a virus with a mutation in codon 215 was detected.A high percentage of patients that have received monotherapy with AZT have genotypic resistance to the drug. This resistance is associated with clinical and immunological derangement in 70% of these subjects.
22. Human papillomavirus,Virus papiloma humano
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Abarca, K., Beca, J. P., Brañes, J., Castillo, C., Ferreccio, C., Gaete, V., Gayán, P., Vega, A. M., Oyarzún, P., Peredo, C., Ana Pereira, Prieto, M., Puga, M., Ramírez, E., Suárez, E., Terrazas, S., Toro, J., Valenzuela, M. T., Villarroel, J., and Zubarew, T.
23. Influenza: the reemergence of an ancient disease and its risk of pandemia,Influenza: reemergencia de una antigua enfermedad y el potencial riesgo de una nueva pandemia
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Jofré, L., Perret, C., Dabanch, J., Abarca, K., Olivares, R., Luchsinger, V., Aguilera, X., Sotomayor, V., and Andrea Olea
24. Primary and booster vaccination in Latin American children with a DTPw-HBV/Hib combination: a randomized controlled trial
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Collard Alix, Casellas Javier, Abarca Katia, Gentile Angela, Tregnaghi Miguel, Espinoza Felix, Lefevre Inge, and Jacquet Jeanne-Marie
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Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background Diphtheria-tetanus-whole-cell pertussis (DTPw)-based combination vaccines are an attractive option to rapidly achieve high coverage and protection against other important pathogens, such as hepatitis B virus (HBV) and Haemophilus influenzae type B (Hib). To ensure adequate antigen supply, GlaxoSmithKline Biologicals has introduced a new DTPw antigen source and developed a new DTPw-HBV/Hib combination vaccine containing a reduced amount of Hib polyribosylribitol phosphate (PRP). This study was undertaken to compare the immunogenicity and reactogenicity of this new DTPw-HBV/Hib vaccine with a licensed DTPw-HBV/Hib vaccine (Tritanrix™-HBV/Hib). Methods This was a randomized, partially-blind, multicenter study in three countries in Latin America (Argentina, Chile and Nicaragua). Healthy children received either the new DTPw-HBV/Hib vaccine (1 of 3 lots; n = 439; double-blind) or Tritanrix™-HBV/Hib (n = 146; single-blind) co-administered with oral poliovirus vaccine (OPV) at 2, 4 and 6 months, with a booster dose at 18-24 months. Results One month after the end of the 3-dose primary vaccination course, the new DTPw-HBV/Hib vaccine was non-inferior to Tritanrix™-HBV/Hib in terms of seroprotection/vaccine response rates for all component antigens; ≥97.3% and ≥93.9% of subjects in the two groups, respectively, had seroprotective levels of antibodies against diphtheria, tetanus, hepatitis B and Hib and a vaccine response to the pertussis component. Persistence of antibodies against all vaccine antigens was comparable between groups, with marked increases in all antibody concentrations after booster administration in both groups. Both vaccines were generally well-tolerated as primary and booster doses. Conclusions Results confirm the suitability of this new DTPw-HBV/Hib vaccine comprising antigens from a new source and a reduced PRP content for inclusion into routine childhood vaccination programs. Trial registration http://www.clinicaltrials.gov NCT00332566
- Published
- 2010
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25. A phase 2, randomized, double-blind safety and pharmacokinetic assessment of respiratory syncytial virus (RSV) prophylaxis with motavizumab and palivizumab administered in the same season
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Griffin M Pamela, Abarca Katia, Trenholme Adrian, Fernández Pilar, Hultquist Micki, Harris Brian, and Losonsky Genevieve A
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Pediatrics ,RJ1-570 - Abstract
Abstract Background Respiratory syncytial virus (RSV) is an important pathogen causing annual epidemics of bronchiolitis and pneumonia among infants worldwide. High-risk infants currently receive RSV prophylaxis with palivizumab, a humanized RSV monoclonal antibody (MAb). In preclinical in vitro and in vivo (cotton-rat model) studies, motavizumab, a new RSV MAb, was shown to have greater anti-RSV activity than palivizumab. Motavizumab is currently under review for licensing approval. Since both MAbs may be available concurrently, this study evaluated their safety and tolerability when administered sequentially during the same RSV season. Methods Between April 2006 and May 2006, 260 high-risk infants were randomly assigned 1:1:1 to receive monthly intramuscular injections: 2 doses of motavizumab followed by 3 doses of palivizumab (M/P); 2 doses of palivizumab followed by 3 doses of motavizumab (P/M); or 5 doses of motavizumab (control). Adverse events (AEs, serious AEs [SAEs]), development of antidrug antibody (ADA), and serum drug trough concentrations were assessed. Results Most children received all 5 doses (246/260 [94.6%]) and completed the study (241/260 [92.7%]). While overall AE rates were similar (mostly level 1 or 2 in severity), SAEs and level 3 AEs occurred more frequently in the M/P group (SAEs: 22.9% M/P, 8.4% P/M, 11.8% motavizumab only; level 3 AEs: 15.7% M/P, 6.0% P/M, 6.5% motavizumab only). This trend in AE rates occurred before and after switching from motavizumab to palivizumab, suggesting a cause other than the combined regimen. Frequencies of AEs judged by the investigator to be related to study drug were similar among groups. Two deaths occurred on study (both in the M/P group, before palivizumab administration); neither was considered by the site investigator to be related to study drug. Mean serum drug trough concentrations were comparable among groups; ADA detection was infrequent (5.1% or less of any group). Conclusions The conclusions drawn from this study are limited by the small sample size per group. However, within this small study, overall AE rates, serum drug trough concentrations, and development of ADA associated with administering motavizumab and palivizumab sequentially to high-risk children appear comparable to administering motavizumab alone during the same RSV season. Trial Registration clinicaltrials.gov NCT00316264
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- 2010
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26. KAWASAKI DISEASE. AN EXPERIENCE OF 15 YEARS. SANTIAGO OF CHILE
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Barría, Raúl, Abarca, K, Stegmaier, Helen, Heusser, F, Céspedes, P, and Talesnik, E
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- 2006
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27. Immune responses during COVID-19 breakthrough cases in vaccinated children and adolescents.
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Rivera-Pérez D, Méndez C, Diethelm-Varela B, Melo-González F, Vázquez Y, Meng X, Xin Q, Fasce RA, Fernández J, Mora J, Ramirez E, Acevedo ML, Valiente-Echeverría F, Soto-Rifo R, Grifoni A, Weiskopf D, Sette A, Astudillo P, Le Corre N, Abarca K, Perret C, González PA, Soto JA, Bueno SM, and Kalergis AM
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- Adolescent, Child, Child, Preschool, Female, Humans, Male, CD8-Positive T-Lymphocytes immunology, Cytokines immunology, Cytokines blood, Immunoglobulin G blood, Immunoglobulin G immunology, Vaccination, Follow-Up Studies, Antibodies, Neutralizing blood, Antibodies, Neutralizing immunology, Antibodies, Viral blood, Antibodies, Viral immunology, CD4-Positive T-Lymphocytes immunology, COVID-19 immunology, COVID-19 prevention & control, COVID-19 Vaccines immunology, COVID-19 Vaccines administration & dosage, SARS-CoV-2 immunology
- Abstract
Background: Vaccine effectiveness against SARS-CoV-2 infection has been somewhat limited due to the widespread dissemination of the Omicron variant, its subvariants, and the immune response dynamics of the naturally infected with the virus., Methods: Twelve subjects between 3-17 years old (yo), vaccinated with two doses of CoronaVac
® , were followed and diagnosed as breakthrough cases starting 14 days after receiving the second dose. Total IgGs against different SARS-CoV-2 proteins and the neutralizing capacity of these antibodies after infection were measured in plasma. The activation of CD4+ and CD8+ T cells was evaluated in peripheral blood mononuclear cells stimulated with peptides derived from the proteins from the wild-type (WT) virus and Omicron subvariants by flow cytometry, as well as different cytokines secretion by a Multiplex assay., Results: 2 to 8 weeks post-infection, compared to 4 weeks after 2nd dose of vaccine, there was a 146.5-fold increase in neutralizing antibody titers against Omicron and a 38.7-fold increase against WT SARS-CoV-2. Subjects showed an increase in total IgG levels against the S1, N, M, and NSP8 proteins of the WT virus. Activated CD4+ T cells showed a significant increase in response to the BA.2 subvariant (p<0.001). Finally, the secretion of IL-2 and IFN-γ cytokines showed a discreet decrease trend after infection in some subjects., Conclusion: SARS-CoV-2 infection in the pediatric population vaccinated with an inactivated SARS-CoV-2 vaccine produced an increase in neutralizing antibodies against Omicron and increased specific IgG antibodies for different SARS-CoV-2 proteins. CD4+ T cell activation was also increased, suggesting a conserved cellular response against the Omicron subvariants, whereas Th1-type cytokine secretion tended to decrease., Clinical Trial Registration: clinicaltrials.gov #NCT04992260., Competing Interests: XM and QX are SINOVAC Biotech employees, contributed to the conceptualization of the study, and did not participate in the analysis or interpretation of the data presented in the manuscript. AS is a consultant for AstraZeneca Pharmaceuticals, Calyptus Pharmaceuticals, Inc, Darwin Health, EmerVax, EUROIMMUN, F. Hoffman-La Roche Ltd, Fortress Biotech, Gilead Sciences, Granite bio., Gritstone Oncology, Guggenheim Securities, Moderna, Pfizer, RiverVest Venture Partners, and Turnstone Biologics. AG is a consultant for Pfizer and Sanofi. La Jolla Institute for Immunology (LJI) has filed for patent protection for various aspects of T cell epitope and vaccine design work. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Rivera-Pérez, Méndez, Diethelm-Varela, Melo-González, Vázquez, Meng, Xin, Fasce, Fernández, Mora, Ramirez, Acevedo, Valiente-Echeverría, Soto-Rifo, Grifoni, Weiskopf, Sette, Astudillo, Le Corre, Abarca, Perret, González, Soto, Bueno and Kalergis.)- Published
- 2024
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28. Phase 3 trial to evaluate the safety, tolerability, and immunogenicity of V114, a 15-valent pneumococcal conjugate vaccine, followed by 23-valent pneumococcal polysaccharide vaccine 6 months later, in at-risk adults 18-49 years of age (PNEU-DAY): A subgroup analysis by baseline risk factors.
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Hammitt LL, Quinn D, Janczewska E, Pasquel FJ, Tytus R, Reddy KR, Abarca K, Khaertynova IM, Dagan R, Dawson R, McCauley J, Shekar T, Fu W, Pedley A, Sterling T, Tamms G, Musey L, and Buchwald UK
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- Humans, Adult, Vaccines, Conjugate, Double-Blind Method, Pneumococcal Vaccines adverse effects, Antibodies, Bacterial, Immunogenicity, Vaccine, Streptococcus pneumoniae, Pneumococcal Infections prevention & control
- Abstract
Immunocompetent adults with certain medical and behavioral factors are at increased risk of pneumococcal disease. In some countries, sequential vaccination with 13-valent pneumococcal conjugate vaccine (PCV13) followed by 23-valent pneumococcal polysaccharide vaccine (PPSV23) is recommended for at-risk adults. This subgroup analysis from a phase 3 study evaluated the safety, tolerability, and immunogenicity of sequential administration of either V114 (a 15-valent PCV containing serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, 22F, 23F, and 33F) or PCV13, followed 6 months later by PPSV23, in immunocompetent adults 18-49 years of age with pre-defined risk factors for pneumococcal disease. Safety and immunogenicity post-vaccination were analyzed by type and baseline number of risk factors for pneumococcal disease (1 and ≥2 risk factors). This analysis included 1,131 participants randomized 3:1 to receive either V114 or PCV13, followed by PPSV23. The majority (73.1%) of participants had at least one risk factor. Safety and tolerability profiles of V114 and PCV13 were similar across risk factor groups. V114 administered either alone or sequentially with PPSV23 6 months later was immunogenic for all 15 serotypes, including those not contained in PCV13, regardless of the number of baseline risk factors. V114 has the potential to broaden serotype coverage for at-risk adults.
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- 2023
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29. Different Safety Pattern of an Inactivated SARS-CoV-2 Vaccine (CoronaVac ® ) According to Age Group in a Pediatric Population from 3 to 17 Years Old, in an Open-Label Study in Chile.
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Le Corre N, Abarca K, Astudillo P, Potin M, López S, Goldsack M, Valenzuela V, Schilling A, Gaete V, Rubio L, Calvo M, Twele L, González M, Fuentes D, Gutiérrez V, Reyes F, Tapia LI, Villena R, Retamal-Díaz A, Cárdenas A, Alarcón-Bustamante E, Meng X, Xin Q, González-Aramundiz JV, Álvarez-Figueroa MJ, González PA, Bueno SM, Soto JA, On Behalf Of The PedCoronaVac Cl Study Group, Perret C, and Kalergis AM
- Abstract
During the COVID-19 pandemic, the importance of vaccinating children against SARS-CoV-2 was rapidly established. This study describes the safety of CoronaVac
® in children and adolescents between 3- and 17-years-old in a multicenter study in Chile with two vaccine doses in a 4-week interval. For all participants, immediate adverse events (AEs), serious AEs (SAEs), and AEs of special interest (AESIs) were registered throughout the study. In the safety subgroup, AEs were recorded 28 days after each dose. COVID-19 surveillance was performed throughout the study. A total of 1139 individuals received the first and 1102 the second dose of CoronaVac® ; 835 were in the safety subgroup. The first dose showed the highest number of AEs: up to 22.2% of participants reported any local and 17.1% systemic AE. AEs were more frequent in adolescents after the first dose, were transient, and mainly mild. Pain at the inoculation site was the most frequent AE for all ages. Fever was the most frequent systemic AE for 3-5 years old and headache in 6-17 years old. No SAEs or AESIs related to vaccination occurred. Most of the COVID-19 cases were mild and managed as outpatients. CoronaVac® was safe and well tolerated in children and adolescents, with different safety patterns according to age.- Published
- 2023
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30. Characterization of the humoral and cellular immunity induced by a recombinant BCG vaccine for the respiratory syncytial virus in healthy adults.
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Pacheco GA, Andrade CA, Gálvez NMS, Vázquez Y, Rodríguez-Guilarte L, Abarca K, González PA, Bueno SM, and Kalergis AM
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- Humans, Adult, Infant, Newborn, BCG Vaccine, Immunity, Cellular, Immunization, Vaccination, Respiratory Syncytial Virus, Human
- Abstract
Introduction: The human respiratory syncytial virus (hRSV) is responsible for most respiratory tract infections in infants. Even though currently there are no approved hRSV vaccines for newborns or infants, several candidates are being developed. rBCG-N-hRSV is a vaccine candidate previously shown to be safe in a phase I clinical trial in adults (clinicaltrials.gov identifier #NCT03213405). Here, secondary immunogenicity analyses were performed on these samples., Methods: PBMCs isolated from immunized volunteers were stimulated with hRSV or mycobacterial antigens to evaluate cytokines and cytotoxic T cell-derived molecules and the expansion of memory T cell subsets. Complement C1q binding and IgG subclass composition of serum antibodies were assessed., Results: Compared to levels detected prior to vaccination, perforin-, granzyme B-, and IFN-γ-producing PBMCs responding to stimulus increased after immunization, along with their effector memory response. N-hRSV- and mycobacterial-specific antibodies from rBCG-N-hRSV-immunized subjects bound C1q., Conclusion: Immunization with rBCG-N-hRSV induces cellular and humoral immune responses, supporting that rBCG-N-hRSV is immunogenic and safe in healthy individuals., Clinical Trial Registration: https://classic.clinicaltrials.gov/ct2/show/, identifier NCT03213405., Competing Interests: PG, SB, and AK hold a patent for the rBCG-N-hRSV vaccine with Pontificia Universidad Católica de Chile PCT/US2008/076682. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Pacheco, Andrade, Gálvez, Vázquez, Rodríguez-Guilarte, Abarca, González, Bueno and Kalergis.)
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- 2023
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31. Notes from the Field: Scrub Typhus Outbreak - Los Lagos Region, Chile, January-February 2023.
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Weitzel T, Martínez-Valdebenito C, Acosta-Jamett G, and Abarca K
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- Humans, Chile epidemiology, Disease Outbreaks, Scrub Typhus epidemiology
- Abstract
Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. Thomas Weitzel, Constanza Martínez-Valdebenito, Katia Abarca, and Gerardo Acosta-Jamett report institutional support (including equipment and laboratory materials for diagnostic testing), travel support, and honoraria from the National Research and Development Agency of Chile (Agencia Nacional de Investigación y Desarrollo) and the National Fund for Scientific and Technological Development (Fondo Nacional de Desarrollo Científico y Tecnológico). No other potential conflicts of interest were disclosed.
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- 2023
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32. Humoral and cellular response induced by a second booster of an inactivated SARS-CoV-2 vaccine in adults.
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Méndez C, Peñaloza HF, Schultz BM, Piña-Iturbe A, Ríos M, Moreno-Tapia D, Pereira-Sánchez P, Leighton D, Orellana C, Covarrubias C, Gálvez NMS, Soto JA, Duarte LF, Rivera-Pérez D, Vázquez Y, Cabrera A, Bustos S, Iturriaga C, Urzua M, Navarrete MS, Rojas Á, Fasce RA, Fernández J, Mora J, Ramírez E, Gaete-Argel A, Acevedo M, Valiente-Echeverría F, Soto-Rifo R, Weiskopf D, Grifoni A, Sette A, Zeng G, Meng W, González-Aramundiz JV, González PA, Abarca K, Melo-González F, Bueno SM, and Kalergis AM
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- Adult, Humans, Pandemics, SARS-CoV-2, Vaccines, Inactivated, Antibodies, Viral, Antibodies, Neutralizing, COVID-19 Vaccines, COVID-19 prevention & control
- Abstract
Background: The Omicron variant has challenged the control of the COVID-19 pandemic due to its immuno-evasive properties. The administration of a booster dose of a SARS-CoV-2 vaccine showed positive effects in the immunogenicity against SARS-CoV-2, effect that is even enhanced after the administration of a second booster., Methods: During a phase-3 clinical trial, we evaluated the effect of a second booster of CoronaVac®, an inactivated vaccine administered 6 months after the first booster, in the neutralization of SARS-CoV-2 (n = 87). In parallel, cellular immunity (n = 45) was analyzed in stimulated peripheral mononuclear cells by flow cytometry and ELISPOT., Findings: Although a 2.5-fold increase in neutralization of the ancestral SARS-CoV-2 was observed after the second booster when compared with prior its administration (Geometric mean units p < 0.0001; Geometric mean titer p = 0.0002), a poor neutralization against the Omicron variant was detected. Additionally, the activation of specific CD4
+ T lymphocytes remained stable after the second booster and, importantly, equivalent activation of CD4+ T lymphocytes against the Omicron variant and the ancestral SARS-CoV-2 were found., Interpretation: Although the neutralizing response against the Omicron variant after the second booster of CoronaVac® was slightly increased, these levels are far from those observed against the ancestral SARS-CoV-2 and could most likely fail to neutralize the virus. In contrast, a robust CD4+ T cell response may confer protection against the Omicron variant., Funding: The Ministry of Health, Government of Chile, the Confederation of Production and Commerce, Chile and SINOVAC Biotech.NIHNIAID. The Millennium Institute on Immunology and Immunotherapy., Competing Interests: Declaration of interests GZ and WM are SINOVAC Biotech employees and contributed to the conceptualization of the study (clinical protocol and eCRF design) and did not participate in the analysis or interpretation of the data presented in the manuscript. A.S. is a consultant for Gritstone Bio, Flow Pharma, ImmunoScape, Moderna, AstraZeneca, Avalia, Fortress, Repertoire, Gilead, Gerson Lehrman Group, RiverVest, MedaCorp, and Guggenheim. La Jolla Institute for Immunology (LJI) has filed for patent protection for various aspects of T cell epitope and vaccine design work. All other authors declare no conflict of interest., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)- Published
- 2023
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33. Eco-epidemiology of rodent-associated trombiculid mites and infection with Orientia spp. in Southern Chile.
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Silva de la Fuente MC, Pérez C, Martínez-Valdebenito C, Pérez R, Vial C, Stekolnikov A, Abarca K, Weitzel T, and Acosta-Jamett G
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- Animals, Rodentia, Orientia, Chile epidemiology, Scrub Typhus epidemiology, Scrub Typhus microbiology, Trombiculidae microbiology, Orientia tsutsugamushi genetics
- Abstract
Background: Scrub typhus is a potentially severe infection caused by bacteria of the genus Orientia, endemic in Asia-Pacific and recently discovered in southern Chile. The presented study aimed to determine the prevalence and species richness of rodent-associated trombiculid mites and their infection with Orientia spp. in different areas of two regions in southern Chile., Methodology/principal Findings: During summer 2020, trombiculid mites were collected from rodents captured in three areas in southern Chile known to be endemic for scrub typhus (Cochamó and Chiloé Island in the Los Lagos Region and Tortel in the Aysén Region). A total of 132 rodents belonging to five species were captured using Sherman-like traps; 89.4% were infested with trombiculids. Mite specimens were morphologically identified and subsequently tested by Orientia-specific qPCR. Six mite species were identified. Among chigger-infested rodents, 33.9% carried Orientia-positive mites; this rate was higher in Tortel (63.8%) than in Cochamó (45.0%) and Chiloé Island (2.0%). The analysis of individual mites (n = 901) revealed that 31.2% of Herpetacarus antarctica samples (n = 202) were positive for Orientia DNA; the prevalence was 7.0% in Paratrombicula neuquenensis (n = 213), 6.9% in Herpetacarus eloisae (n = 144), 3.6% in Argentinacarus expansus (n = 55), and 0% in Paratrombicula goffi (n = 110) and Quadraseta chiloensis (n = 177). The southernmost site (Tortel) showed the highest rates of trombiculid infestation, trombiculid load, and Orientia infection in the captured rodents., Conclusions/significance: Our study provides new insights into the trombiculid fauna and prevalence of Orientia in mites collected from wild rodents in southern Chile. Orientia DNA was detected in four of the six mite species. Rates of infestation, mite loads, and Orientia prevalences differed geographically and were highest in the Aysén Region. Our data improve our knowledge on possible vectors of scrub typhus and their distribution in Chile., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Silva de la Fuente et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)
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- 2023
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34. Inactivated Vaccine-Induced SARS-CoV-2 Variant-Specific Immunity in Children.
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Soto JA, Melo-González F, Gutierrez-Vera C, Schultz BM, Berríos-Rojas RV, Rivera-Pérez D, Piña-Iturbe A, Hoppe-Elsholz G, Duarte LF, Vázquez Y, Moreno-Tapia D, Ríos M, Palacios PA, Garcia-Betancourt R, Santibañez Á, Pacheco GA, Mendez C, Andrade CA, Silva PH, Diethelm-Varela B, Astudillo P, Calvo M, Cárdenas A, González M, Goldsack M, Gutiérrez V, Potin M, Schilling A, Tapia LI, Twele L, Villena R, Grifoni A, Sette A, Weiskopf D, Fasce RA, Fernández J, Mora J, Ramírez E, Gaete-Argel A, Acevedo ML, Valiente-Echeverría F, Soto-Rifo R, Retamal-Díaz A, Muñoz-Jofré N, Meng X, Xin Q, Alarcón-Bustamante E, González-Aramundiz JV, Le Corre N, Álvarez-Figueroa MJ, González PA, Abarca K, Perret C, Carreño LJ, Bueno SM, and Kalergis AM
- Subjects
- Adolescent, Humans, Child, Child, Preschool, Antibodies, Neutralizing, Vaccines, Inactivated, Antibodies, Viral, SARS-CoV-2, COVID-19
- Abstract
Multiple vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been evaluated in clinical trials. However, trials addressing the immune response in the pediatric population are scarce. The inactivated vaccine CoronaVac has been shown to be safe and immunogenic in a phase 1/2 clinical trial in a pediatric cohort in China. Here, we report interim safety and immunogenicity results of a phase 3 clinical trial for CoronaVac in healthy children and adolescents in Chile. Participants 3 to 17 years old received two doses of CoronaVac in a 4-week interval until 31 December 2021. Local and systemic adverse reactions were registered for volunteers who received one or two doses of CoronaVac. Whole-blood samples were collected from a subgroup of 148 participants for humoral and cellular immunity analyses. The main adverse reaction reported after the first and second doses was pain at the injection site. Four weeks after the second dose, an increase in neutralizing antibody titer was observed in subjects relative to their baseline visit. Similar results were found for activation of specific CD4
+ T cells. Neutralizing antibodies were identified against the Delta and Omicron variants. However, these titers were lower than those for the D614G strain. Importantly, comparable CD4+ T cell responses were detected against these variants of concern. Therefore, CoronaVac is safe and immunogenic in subjects 3 to 17 years old, inducing neutralizing antibody secretion and activating CD4+ T cells against SARS-CoV-2 and its variants. (This study has been registered at ClinicalTrials.gov under no. NCT04992260.) IMPORTANCE This work evaluated the immune response induced by two doses of CoronaVac separated by 4 weeks in healthy children and adolescents in Chile. To date, few studies have described the effects of CoronaVac in the pediatric population. Therefore, it is essential to generate knowledge regarding the protection of vaccines in this population. Along these lines, we reported the anti-S humoral response and cellular immune response to several SARS-CoV-2 proteins that have been published and recently studied. Here, we show that a vaccination schedule consisting of two doses separated by 4 weeks induces the secretion of neutralizing antibodies against SARS-CoV-2. Furthermore, CoronaVac induces the activation of CD4+ T cells upon stimulation with peptides from the proteome of SARS-CoV-2. These results indicate that, even though the neutralizing antibody response induced by vaccination decreases against the Delta and Omicron variants, the cellular response against these variants is comparable to the response against the ancestral strain D614G, even being significantly higher against Omicron.- Published
- 2022
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35. A Booster Dose of CoronaVac Increases Neutralizing Antibodies and T Cells that Recognize Delta and Omicron Variants of Concern.
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Schultz BM, Melo-González F, Duarte LF, Gálvez NMS, Pacheco GA, Soto JA, Berríos-Rojas RV, González LA, Moreno-Tapia D, Rivera-Pérez D, Ríos M, Vázquez Y, Hoppe-Elsholz G, Andrade-Parra CA, Vallejos OP, Piña-Iturbe A, Iturriaga C, Urzua M, Navarrete MS, Rojas Á, Fasce R, Fernández J, Mora J, Ramírez E, Gaete-Argel A, Acevedo ML, Valiente-Echeverría F, Soto-Rifo R, Weiskopf D, Grifoni A, Sette A, Zeng G, Meng W, González-Aramundiz JV, González PA, Abarca K, Kalergis AM, and Bueno SM
- Subjects
- Adult, Antibodies, Neutralizing, Antibodies, Viral, COVID-19 Vaccines, Humans, SARS-CoV-2, T-Lymphocytes, COVID-19 prevention & control, Viral Vaccines
- Abstract
CoronaVac is an inactivated SARS-CoV-2 vaccine approved by the World Health Organization (WHO). Previous studies reported increased levels of neutralizing antibodies and specific T cells 2 and 4 weeks after two doses of CoronaVac; these levels were significantly reduced at 6 to 8 months after the two doses. Here, we report the effect of a booster dose of CoronaVac on the anti-SARS-CoV-2 immune response generated against the variants of concern (VOCs), Delta and Omicron, in adults participating in a phase III clinical trial in Chile. Volunteers immunized with two doses of CoronaVac in a 4-week interval received a booster dose of the same vaccine between 24 and 30 weeks after the second dose. Neutralization capacities and T cell activation against VOCs Delta and Omicron were assessed 4 weeks after the booster dose. We observed a significant increase in neutralizing antibodies 4 weeks after the booster dose. We also observed a rise in anti-SARS-CoV-2-specific CD4
+ T cells over time, and these cells reached a peak 4 weeks after the booster dose. Furthermore, neutralizing antibodies and SARS-CoV-2-specific T cells induced by the booster showed activity against VOCs Delta and Omicron. Our results show that a booster dose of CoronaVac increases adults' humoral and cellular anti-SARS-CoV-2 immune responses. In addition, immunity induced by a booster dose of CoronaVac is active against VOCs, suggesting adequate protection. IMPORTANCE CoronaVac is an inactivated vaccine against SARS-CoV-2 that has been approved by WHO for emergency use. Phase III clinical trials are in progress in several countries, including China, Brazil, Turkey, and Chile, and have shown safety and immunogenicity after two doses of the vaccine. This report characterizes immune responses induced by two doses of CoronaVac followed by a booster dose 5 months after the second dose in healthy Chilean adults. The data reported here show that a booster dose increased the immune responses against SARS-CoV-2, enhancing levels of neutralizing antibodies against the ancestral strain and VOCs. Similarly, anti-SARS-CoV-2 CD4+ T cell responses were increased following the booster dose. In contrast, levels of gamma interferon secretion and T cell activation against the VOCs Delta and Omicron were not significantly different from those for the ancestral strain. Therefore, a third dose of CoronaVac in a homologous vaccination schedule improves its immunogenicity in healthy volunteers.- Published
- 2022
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36. Safety and Immunogenicity of an Inactivated Severe Acute Respiratory Syndrome Coronavirus 2 Vaccine in a Subgroup of Healthy Adults in Chile.
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Bueno SM, Abarca K, González PA, Gálvez NMS, Soto JA, Duarte LF, Schultz BM, Pacheco GA, González LA, Vázquez Y, Ríos M, Melo-González F, Rivera-Pérez D, Iturriaga C, Urzúa M, Domínguez A, Andrade CA, Berríos-Rojas RV, Canedo-Marroquín G, Covián C, Moreno-Tapia D, Saavedra F, Vallejos OP, Donato P, Espinoza P, Fuentes D, González M, Guzmán P, Muñoz Venturelli P, Pérez CM, Potin M, Rojas Á, Fasce RA, Fernández J, Mora J, Ramírez E, Gaete-Argel A, Oyarzún-Arrau A, Valiente-Echeverría F, Soto-Rifo R, Weiskopf D, Sette A, Zeng G, Meng W, González-Aramundiz JV, and Kalergis AM
- Subjects
- Adolescent, Adult, Antibodies, Neutralizing, Antibodies, Viral, COVID-19 Vaccines adverse effects, Chile, Double-Blind Method, Humans, Immunogenicity, Vaccine, Immunoglobulin G, Middle Aged, SARS-CoV-2, Vaccines, Inactivated adverse effects, Young Adult, COVID-19 prevention & control, Viral Vaccines
- Abstract
Background: The development of effective vaccines against coronavirus disease 2019 is a global priority. CoronaVac is an inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine with promising safety and immunogenicity profiles. This article reports safety and immunogenicity results obtained for healthy Chilean adults aged ≥18 years in a phase 3 clinical trial., Methods: Volunteers randomly received 2 doses of CoronaVac or placebo, separated by 2 weeks. A total of 434 volunteers were enrolled, 397 aged 18-59 years and 37 aged ≥60 years. Solicited and unsolicited adverse reactions were registered from all volunteers. Blood samples were obtained from a subset of volunteers and analyzed for humoral and cellular measures of immunogenicity., Results: The primary adverse reaction in the 434 volunteers was pain at the injection site, with a higher incidence in the vaccine than in the placebo arm. Adverse reactions observed were mostly mild and local. No severe adverse events were reported. The humoral evaluation was performed on 81 volunteers. Seroconversion rates for specific anti-S1-receptor binding domain (RBD) immunoglobulin G (IgG) were 82.22% and 84.44% in the 18-59 year age group and 62.69% and 70.37% in the ≥60 year age group, 2 and 4 weeks after the second dose, respectively. A significant increase in circulating neutralizing antibodies was detected 2 and 4 weeks after the second dose. The cellular evaluation was performed on 47 volunteers. We detected a significant induction of T-cell responses characterized by the secretion of interferon-γ (IFN-γ) upon stimulation with Mega Pools of peptides from SARS-CoV-2., Conclusions: Immunization with CoronaVac in a 0-14 schedule in Chilean adults aged ≥18 years is safe, induces anti-S1-RBD IgG with neutralizing capacity, activates T cells, and promotes the secretion of IFN-γ upon stimulation with SARS-CoV-2 antigens., (© The Author(s) 2021. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)
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- 2022
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37. Safety and Non-Inferiority Evaluation of Two Immunization Schedules with an Inactivated SARS-CoV-2 Vaccine in Adults: A Randomized Clinical Trial.
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Abarca K, Iturriaga C, Urzúa M, Le Corre N, Pineda A, Fernández C, Domínguez A, González PA, Bueno SM, Donato P, Espinoza P, Fuentes D, González M, Guzmán P, Muñoz-Venturelli P, Pérez CM, Potin M, Rojas Á, González-Aramundiz JV, Gálvez NMS, Aguirre-Boza F, Aljaro S, Bátiz LF, Campisto Y, Cepeda M, Cortés A, López S, Pérez ML, Schilling A, Kalergis AM, and On Behalf Of The CoronaVac Cl Study Group
- Abstract
Several vaccines have been developed to control the COVID-19 pandemic. CoronaVac
® , an inactivated SARS-CoV-2 vaccine, has demonstrated safety and immunogenicity, preventing severe COVID-19 cases. We investigate the safety and non-inferiority of two immunization schedules of CoronaVac® in a non-inferiority trial in healthy adults. A total of 2302 healthy adults were enrolled at 8 centers in Chile and randomly assigned to two vaccination schedules, receiving two doses with either 14 or 28 days between each. The primary safety and efficacy endpoints were solicited adverse events (AEs) within 7 days of each dose, and comparing the number of cases of SARS-CoV-2 infection 14 days after the second dose between the schedules, respectively. The most frequent local AE was pain at the injection site, which was less frequent in participants aged ≥60 years. Other local AEs were reported in less than 5% of participants. The most frequent systemic AEs were headache, fatigue, and myalgia. Most AEs were mild and transient. There were no significant differences for local and systemic AEs between schedules. A total of 58 COVID-19 cases were confirmed, and all but 2 of them were mild. No differences were observed in the proportion of COVID-19 cases between schedules. CoronaVac® is safe, especially in ≥60-year-old participants. Both schedules protected against COVID-19 hospitalization.- Published
- 2022
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38. Novel Vector of Scrub Typhus in Sub-Antarctic Chile: Evidence From Human Exposure.
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Weitzel T, Silva-de la Fuente MC, Martínez-Valdebenito C, Stekolnikov AA, Pérez C, Pérez R, Vial C, Abarca K, and Acosta-Jamett G
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- Animals, Antarctic Regions, Chile epidemiology, Humans, Orientia tsutsugamushi, Scrub Typhus epidemiology, Trombiculidae
- Abstract
The exposure of a research team to chigger mites in southern Chile allowed the first identification of a trombiculid species as vector and reservoir of scrub typhus outside the tsutsugamushi triangle, providing unique insights into the ecology and transmission of this recently discovered rickettsial infection in South America., (© The Author(s) 2021. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)
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- 2022
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39. Development of a New Genus-Specific Quantitative Real-Time PCR Assay for the Diagnosis of Scrub Typhus in South America.
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Jiang J, Martínez-Valdebenito C, Weitzel T, Farris CM, Acosta-Jamett G, Abarca K, and Richards AL
- Abstract
Scrub typhus is a potentially severe rickettsiosis, caused by Orientia tsutsugamushi in the Asia-Pacific region. Recently, however, two distinct pathogens, " Candidatus Orientia chuto" and " Candidatus Orientia chiloensis", have been discovered in the Middle East and South America, respectively. Since the novel pathogens differ significantly from O. tsutsugamushi , many established diagnostic methods are unreliable. This work describes the development and validation of a new quantitative real-time PCR (qPCR) assay (Orien16S) for the detection of all known Orientia species. Based on a 94 bp sequence of the 16S rRNA gene ( rrs ), Orien16S recognized DNA samples from O. tsutsugamushi ( n = 41), Ca. O. chiloensis ( n = 5), and Ca. O. chuto ( n = 1), but was negative for DNA preparations from closely related rickettsiae and other members of the order Rickettsiales ( n = 22) as well as unrelated bacterial species ( n = 11). After its implementation in Chile, the assay was verified, correctly identifying all tested eschar and buffy coat samples ( n = 28) of clinical suspected cases. Furthermore, Orien16S detected Orientia DNA in trombiculid mites collected in endemic regions in southern Chile. The presented novel qPCR assay provides a useful tool for detecting Orientia and diagnosing scrub typhus from all geographical regions., Competing Interests: JJ and AR are employed by the Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Jiang, Martínez-Valdebenito, Weitzel, Farris, Acosta-Jamett, Abarca and Richards.)
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- 2022
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40. A booster dose of an inactivated SARS-CoV-2 vaccine increases neutralizing antibodies and T cells that recognize Delta and Omicron variants of concern.
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Schultz BM, Melo-González F, Duarte LF, Gálvez NM, Pacheco GA, Soto JA, Berríos-Rojas RV, González LA, Moreno-Tapia D, Rivera-Pérez D, Ríos M, Vázquez Y, Hoppe-Elsholz G, Vallejos OP, Iturriaga C, Urzua M, Navarrete MS, Rojas Á, Fasce R, Fernández J, Mora J, Ramírez E, Gaete-Argel A, Acevedo M, Valiente-Echeverría F, Soto-Rifo R, Weiskopf D, Grifoni A, Sette A, Zeng G, Meng W, González-Aramundiz JV, González PA, Abarca K, Kalergis AM, and Bueno SM
- Abstract
Background: CoronaVac
® is an inactivated SARS-CoV-2 vaccine approved by the World Health Organization. Previous studies reported increased levels of neutralizing antibodies and specific T cells two- and four-weeks after two doses of CoronaVac® , but the levels of neutralizing antibodies are reduced at six to eight months after two doses. Here we report the effect of a booster dose of CoronaVac® on the anti-SARS-CoV-2 immune response generated against variants of concern (VOC) Delta and Omicron in adults participating in a phase 3 clinical trial in Chile., Methods: Volunteers immunized with two doses of CoronaVac® in a four-week interval received a booster dose of the same vaccine between twenty-four and thirty weeks after the 2nd dose. Four weeks after the booster dose, neutralizing antibodies and T cell responses were measured. Neutralization capacities and T cell activation against VOC Delta and Omicron were detected at four weeks after the booster dose., Findings: We observed a significant increase in neutralizing antibodies at four weeks after the booster dose. We also observed an increase in CD4+ T cells numbers over time, reaching a peak at four weeks after the booster dose. Furthermore, neutralizing antibodies and SARS-CoV-2 specific T cells induced by the booster showed activity against VOC Delta and Omicron., Interpretation: Our results show that a booster dose of CoronaVac® increases the anti-SARS-CoV-2 humoral and cellular immune responses in adults. Immunity induced by a booster dose of CoronaVac® is active against VOC, suggesting an effective protection.- Published
- 2022
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41. Immunogenicity, Safety, and Tolerability of V114, a 15-Valent Pneumococcal Conjugate Vaccine, in Immunocompetent Adults Aged 18-49 Years With or Without Risk Factors for Pneumococcal Disease: A Randomized Phase 3 Trial (PNEU-DAY).
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Hammitt LL, Quinn D, Janczewska E, Pasquel FJ, Tytus R, Rajender Reddy K, Abarca K, Khaertynova IM, Dagan R, McCauley J, Cheon K, Pedley A, Sterling T, Tamms G, Musey L, and Buchwald UK
- Abstract
Background: Adults with certain medical and behavioral factors are at increased risk for pneumococcal disease (PD). Sequential vaccination with 13-valent pneumococcal conjugate vaccine (PCV13) followed by 23-valent pneumococcal polysaccharide vaccine (PPSV23) is recommended for at-risk adults in some countries., Methods: This phase 3 trial evaluated the safety, tolerability, and immunogenicity of sequential administration of either V114 (a 15-valent PCV containing serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, 22F, 23F, and 33F) or PCV13, followed 6 months later by PPSV23, in immunocompetent adults aged 18-49 years with or without predefined risk factors for PD (NCT03547167). Overall, 1515 participants were randomized 3:1 to receive either V114 or PCV13, followed by PPSV23., Results: Most common solicited adverse events (AEs) following administration of V114 or PCV13 as well as PPSV23 were injection-site pain and fatigue. The proportion of participants with AEs was comparable in both groups. V114 and PCV13 were immunogenic based on opsonophagocytic activity (OPA) geometric mean titers (GMTs) 30 days postvaccination for all serotypes contained in each respective vaccine. OPA GMTs to the 2 unique serotypes in V114 were robust in the V114 group. PPSV23 was immunogenic for all 15 serotypes contained in V114 in both vaccination groups, including 22F and 33F., Conclusions: V114 administered alone or sequentially with PPSV23 is well tolerated and immunogenic for all 15 serotypes, including those not contained in PCV13, in immunocompetent adults aged 18-49 years with or without certain medical or behavioral risk factors for PD., Clinical Trials Registration: NCT03547167 and EudraCT 2017-004915-38., (© The Author(s) 2021. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)
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- 2021
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42. Recognition of Variants of Concern by Antibodies and T Cells Induced by a SARS-CoV-2 Inactivated Vaccine.
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Melo-González F, Soto JA, González LA, Fernández J, Duarte LF, Schultz BM, Gálvez NMS, Pacheco GA, Ríos M, Vázquez Y, Rivera-Pérez D, Moreno-Tapia D, Iturriaga C, Vallejos OP, Berríos-Rojas RV, Hoppe-Elsholz G, Urzúa M, Bruneau N, Fasce RA, Mora J, Grifoni A, Sette A, Weiskopf D, Zeng G, Meng W, González-Aramundiz JV, González PA, Abarca K, Ramírez E, Kalergis AM, and Bueno SM
- Subjects
- Adolescent, Adult, Angiotensin-Converting Enzyme 2 metabolism, Antibodies, Neutralizing blood, Humans, Interferon-gamma immunology, Middle Aged, Neutralization Tests, SARS-CoV-2 classification, Vaccination, Young Adult, Antibodies, Viral blood, COVID-19 prevention & control, COVID-19 Vaccines immunology, SARS-CoV-2 immunology, Spike Glycoprotein, Coronavirus immunology, T-Lymphocytes immunology, Vaccines, Inactivated immunology
- Abstract
Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus responsible of the current pandemic ongoing all around the world. Since its discovery in 2019, several circulating variants have emerged and some of them are associated with increased infections and death rate. Despite the genetic differences among these variants, vaccines approved for human use have shown a good immunogenic and protective response against them. In Chile, over 70% of the vaccinated population is immunized with CoronaVac, an inactivated SARS-CoV-2 vaccine. The immune response elicited by this vaccine has been described against the first SARS-CoV-2 strain isolated from Wuhan, China and the D614G strain (lineage B). To date, four SARS-CoV-2 variants of concern described have circulated worldwide. Here, we describe the neutralizing capacities of antibodies secreted by volunteers in the Chilean population immunized with CoronaVac against variants of concern Alpha (B.1.1.7), Beta (B.1.351) Gamma (P.1) and Delta (B.617.2)., Methods: Volunteers enrolled in a phase 3 clinical trial were vaccinated with two doses of CoronaVac in 0-14 or 0-28 immunization schedules. Sera samples were used to evaluate the capacity of antibodies induced by the vaccine to block the binding between Receptor Binding Domain (RBD) from variants of concern and the human ACE2 receptor by an in-house ELISA. Further, conventional microneutralization assays were used to test neutralization of SARS-CoV-2 infection. Moreover, interferon-γ-secreting T cells against Spike from variants of concern were evaluated in PBMCs from vaccinated subjects using ELISPOT., Results: CoronaVac promotes the secretion of antibodies able to block the RBD of all the SARS-CoV-2 variants studied. Seropositivity rates of neutralizing antibodies in the population evaluated were over 97% for the lineage B strain, over 80% for Alpha and Gamma variants, over 75% for Delta variant and over 60% for the Beta variant. Geometric means titers of blocking antibodies were reduced when tested against SARS-CoV-2 variants as compared to ancestral strain. We also observed that antibodies from vaccinated subjects were able to neutralize the infection of variants D614G, Alpha, Gamma and Delta in a conventional microneutralization assay. Importantly, after SARS-CoV-2 infection, we observed that the blocking capacity of antibodies from vaccinated volunteers increased up to ten times for all the variants tested. We compared the number of interferon-γ-secreting T cells specific for SARS-CoV-2 Spike WT and variants of concern from vaccinated subjects and we did not detect significant differences., Conclusion: Immunization with CoronaVac in either immunization schedule promotes the secretion of antibodies able to block SARS-CoV-2 variants of concern and partially neutralizes SARS-CoV-2 infection. In addition, it stimulates cellular responses against all variants of concern., Competing Interests: Authors GZ and WM are employed by company SINOVAC Biotech. AS is a consultant for Gritstone Bio, Flow Pharma, Arcturus Therapeutics, ImmunoScape, CellCarta, Avalia, Moderna, Fortress and Repertoire. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. La Jolla Institute for Immunology (LJI) has filed for patent protection for various aspects of T cell epitope and vaccine design work. The authors declare this study received the investigational product (placebo and vaccines) from the company SINOVAC Biotech. SINOVAC employees contributed to the conceptualization of the study (clinical protocol and eCRF design) but did not participate in either the analysis or interpretation of the data shown in this manuscript., (Copyright © 2021 Melo-González, Soto, González, Fernández, Duarte, Schultz, Gálvez, Pacheco, Ríos, Vázquez, Rivera-Pérez, Moreno-Tapia, Iturriaga, Vallejos, Berríos-Rojas, Hoppe-Elsholz, Urzúa, Bruneau, Fasce, Mora, Grifoni, Sette, Weiskopf, Zeng, Meng, González-Aramundiz, González, Abarca, Ramírez, Kalergis and Bueno.)
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- 2021
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43. Immune Profile and Clinical Outcome of Breakthrough Cases After Vaccination With an Inactivated SARS-CoV-2 Vaccine.
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Duarte LF, Gálvez NMS, Iturriaga C, Melo-González F, Soto JA, Schultz BM, Urzúa M, González LA, Vázquez Y, Ríos M, Berríos-Rojas RV, Rivera-Pérez D, Moreno-Tapia D, Pacheco GA, Vallejos OP, Hoppe-Elsholz G, Navarrete MS, Rojas Á, Fasce RA, Fernández J, Mora J, Ramírez E, Zeng G, Meng W, González-Aramundiz JV, González PA, Abarca K, Bueno SM, and Kalergis AM
- Subjects
- Adult, Aged, Antibodies, Neutralizing immunology, Antibodies, Viral immunology, COVID-19 pathology, Chile, Comorbidity, Female, Humans, Immunization Schedule, Immunogenicity, Vaccine immunology, Immunoglobulin G blood, Immunoglobulin G immunology, Interferon-gamma immunology, Lymphocyte Count, Male, Middle Aged, Severity of Illness Index, Vaccination, Young Adult, Antibodies, Neutralizing blood, Antibodies, Viral blood, COVID-19 immunology, COVID-19 Vaccines immunology, SARS-CoV-2 immunology, T-Lymphocytes immunology, Vaccines, Inactivated immunology
- Abstract
Constant efforts to prevent infections by severe acute respiratory syndrome coronavirus 2 (SARS - CoV - 2 ) are actively carried out around the world. Several vaccines are currently approved for emergency use in the population, while ongoing studies continue to provide information on their safety and effectiveness. CoronaVac is an inactivated SARS-CoV-2 vaccine with a good safety and immunogenicity profile as seen in phase 1, 2, and 3 clinical trials around the world, with an effectiveness of 65.9% for symptomatic cases. Although vaccination reduces the risk of disease, infections can still occur during or after completion of the vaccination schedule (breakthrough cases). This report describes the clinical and immunological profile of vaccine breakthrough cases reported in a clinical trial in progress in Chile that is evaluating the safety, immunogenicity, and efficacy of two vaccination schedules of CoronaVac (clinicaltrials.gov NCT04651790). Out of the 2,263 fully vaccinated subjects, at end of June 2021, 45 have reported symptomatic SARS-CoV-2 infection 14 or more days after the second dose (1.99% of fully vaccinated subjects). Of the 45 breakthrough cases, 96% developed mild disease; one case developed a moderate disease; and one developed a severe disease and required mechanical ventilation. Both cases that developed moderate and severe disease were adults over 60 years old and presented comorbidities. The immune response before and after SARS-CoV-2 infection was analyzed in nine vaccine breakthrough cases, revealing that six of them exhibited circulating anti-S1-RBD IgG antibodies with neutralizing capacities after immunization, which showed a significant increase 2 and 4 weeks after symptoms onset. Two cases exhibited low circulating anti-S1-RBD IgG and almost non-existing neutralizing capacity after either vaccination or infection, although they developed a mild disease. An increase in the number of interferon-γ-secreting T cells specific for SARS-CoV-2 was detected 2 weeks after the second dose in seven cases and after symptoms onset. In conclusion, breakthrough cases were mostly mild and did not necessarily correlate with a lack of vaccine-induced immunity, suggesting that other factors, to be defined in future studies, could lead to symptomatic infection after vaccination with CoronaVac., Competing Interests: ZG and MW are SINOVAC employees and contributed to the conceptualization of the study (clinical protocol and eCRF design) and did not participate in the analysis or interpretation of the data presented in the manuscript. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Duarte, Gálvez, Iturriaga, Melo-González, Soto, Schultz, Urzúa, González, Vázquez, Ríos, Berríos-Rojas, Rivera-Pérez, Moreno-Tapia, Pacheco, Vallejos, Hoppe-Elsholz, Navarrete, Rojas, Fasce, Fernández, Mora, Ramírez, Zeng, Meng, González-Aramundiz, González, Abarca, Bueno and Kalergis.)
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- 2021
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44. Interim report: Safety and immunogenicity of an inactivated vaccine against SARS-CoV-2 in healthy chilean adults in a phase 3 clinical trial.
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Bueno SM, Abarca K, González PA, Gálvez NM, Soto JA, Duarte LF, Schultz BM, Pacheco GA, González LA, Vázquez Y, Ríos M, Melo-González F, Rivera-Pérez D, Iturriaga C, Urzúa M, Dominguez A, Andrade CA, Berrios RV, Canedo-Marroquín G, Covián C, Moreno-Tapia D, Saavedra F, Vallejos OP, Donato P, Espinoza P, Fuentes D, González M, Guzmán P, Muñoz-Venturelli P, Pérez CM, Potin M, Rojas A, Fasce R, Fernández J, Mora J, Ramírez E, Gaete-Argel A, Oyarzún-Arrau A, Valiente-Echeverría F, Soto-Rifo R, Weiskopf D, Sette A, Zeng G, Meng W, González-Aramundiz JV, and Kalergis AM
- Abstract
Background: The ongoing COVID-19 pandemic has had a significant impact worldwide, with an incommensurable social and economic burden. The rapid development of safe and protective vaccines against this disease is a global priority. CoronaVac is a vaccine prototype based on inactivated SARS-CoV-2, which has shown promising safety and immunogenicity profiles in pre-clinical studies and phase 1/2 trials in China. To this day, four phase 3 clinical trials are ongoing with CoronaVac in Brazil, Indonesia, Turkey, and Chile. This article reports the safety and immunogenicity results obtained in a subgroup of participants aged 18 years and older enrolled in the phase 3 Clinical Trial held in Chile., Methods: This is a multicenter phase 3 clinical trial. Healthcare workers aged 18 years and older were randomly assigned to receive two doses of CoronaVac or placebo separated by two weeks (0-14). We report preliminary safety results obtained for a subset of 434 participants, and antibody and cell-mediated immunity results obtained in a subset of participants assigned to the immunogenicity arm. The primary and secondary aims of the study include the evaluation of safety parameters and immunogenicity against SARS-CoV-2 after immunization, respectively. This trial is registered at clinicaltrials.gov ( NCT04651790 )., Findings: The recruitment of participants occurred between November 27
th , 2020, until January 9th , 2021. 434 participants were enrolled, 397 were 18-59 years old, and 37 were ≥60 years old. Of these, 270 were immunized with CoronaVac, and the remaining 164 participants were inoculated with the corresponding placebo. The primary adverse reaction was pain at the injection site, with a higher incidence in the vaccine arm (55.6%) than in the placebo arm (40.0%). Moreover, the incidence of pain at the injection site in the 18-59 years old group was 58.4% as compared to 32.0% in the ≥60 years old group. The seroconversion rate for specific anti-S1-RBD IgG was 47.8% for the 18-59 years old group 14 days post immunization (p.i.) and 95.6% 28 and 42 days p.i. For the ≥60 years old group, the seroconversion rate was 18.1%, 100%, and 87.5% at 14, 28, and 42 days p.i., respectively. Importantly, we observed a 95.7% seroconversion rate in neutralizing antibodies for the 18-59 years old group 28 and 42 days p.i. The ≥60 years old group exhibited seroconversion rates of 90.0% and 100% at 28 and 42 days p.i. Interestingly, we did not observe a significant seroconversion rate of anti-N-SARS-CoV-2 IgG for the 18-59 years old group. For the participants ≥60 years old, a modest rate of seroconversion at 42 days p.i. was observed (37.5%). We observed a significant induction of a T cell response characterized by the secretion of IFN-γ upon stimulation with Mega Pools of peptides derived from SARS-CoV-2 proteins. No significant differences between the two age groups were observed for cell-mediated immunity., Interpretation: Immunization with CoronaVac in a 0-14 schedule in adults of 18 years and older in the Chilean population is safe and induces specific IgG production against the S1-RBD with neutralizing capacity, as well as the activation of T cells secreting IFN-γ, upon recognition of SARS-CoV-2 antigens., Funding: Ministry of Health of the Chilean Government; Confederation of Production and Commerce, Chile; Consortium of Universities for Vaccines and Therapies against COVID-19, Chile; Millennium Institute on Immunology and Immunotherapy.- Published
- 2021
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45. Chigger Mites (Acariformes: Trombiculidae) of Chiloé Island, Chile, With Descriptions of Two New Species and New Data on the Genus Herpetacarus.
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Silva-de la Fuente MC, Stekolnikov AA, Weitzel T, Beltrami E, Martínez-Valdebenito C, Abarca K, and Acosta-Jamett G
- Subjects
- Animals, Biodiversity, Chile, Islands, Trombiculidae anatomy & histology, Trombiculidae classification
- Abstract
Three species of chigger mites are recorded in our collections from four species of cricetid rodents on Chiloé Island (southern Chile, Los Lagos Region), an area endemic to scrub typhus (Orientia sp.). Two species are described as new-Herpetacarus (Abonnencia) eloisae sp. nov. and Quadraseta chiloensis sp. nov. One species, Paratrombicula goffiStekolnikov and González-Acuña 2012, is for the first time recorded on a mammal host (one species of cricetid rodent), and its distribution is extended to the Los Lagos Region of Chile. The genus ProschoengastiaVercammen-Grandjean, 1967 is synonymized with the subgenus Herpetacarus (Abonnencia)Vercammen-Grandjean, 1960, and four new combinations are established: Herpetacarus (Abonnencia) herniosa (Brennan and Jones, 1961), comb. nov., Herpetacarus (Abonnencia) insolita (Brennan and Jones, 1961), comb. nov., Herpetacarus (Abonnencia) macrochaeta (Brennan and Jones, 1961), comb. nov., and Herpetacarus (Abonnencia) antarctica (Stekolnikov and Gonzalez-Acuña, 2015), comb. nov., (© The Author(s) 2020. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)
- Published
- 2021
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46. Clinical and serological profile of asymptomatic and non-severe symptomatic COVID-19 cases: Lessons from a longitudinal study in primary care in Latin America.
- Author
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Puschel K, Ferreccio C, Peñaloza B, Abarca K, Rojas MP, Tellez A, Moore P, Cea AM, Wilson C, Cid V, and Montero J
- Abstract
Background: Chile has one of the highest incidences of COVID-19 infection in the world. Primary care can play a key role in early detection and containment of the disease. There is a lack of information on the clinical profile of patients with suspected COVID-19 in primary care, and controversy on the effectiveness of rapid serologic tests in the diagnosis and surveillance of the disease., Aim: To assess the effectiveness of rapid serologic testing in detection and surveillance of COVID-19 cases in primary care., Design & Setting: A longitudinal study was undertaken, which was based on a non-random sample of 522 participants, including 304 symptomatic patients and 218 high-risk asymptomatic individuals. They were receiving care at four primary health clinics in an underserved area in Santiago, Chile., Method: The participants were systematically assessed and tested for COVID-19 with reverse transcriptase-polymerase chain reaction (RT-PCR) and serology at baseline, and were followed clinically and serologically for 3 weeks., Results: The prevalence rate of RT-PCR confirmed COVID-19 cases were 3.5 times higher in symptomatic patients (27.5%; 95% confidence interval [CI] = 22.1 to 32.8) compared with asymptomatic participants (7.9%; 95% CI = 4.3 to 11.6). Similarly, the immune response was significantly different between both groups. Sensitivity of serologic testing was 57.8% (95% CI = 44.8 to 70.1) during the third week of follow-up and specificity was 98.4% (95% CI = 95.5 to 99.7)., Conclusion: Rapid serologic testing is ineffective for detecting asymptomatic or non-severe cases of COVID-19 at early stages of the disease, but can be of value for surveillance of immunity response in primary care. The clinical profile and immune response of patients with COVID-19 in primary care differs from those in hospital-based populations., (Copyright © 2020, The Authors.)
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- 2021
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47. Scrub typhus in Chile.
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Concha-Rogazy M, Kinzel-Maluje F, Pinto-Santana C, Sánchez-Sánchez N, and Abarca K
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- Chile epidemiology, Humans, Scrub Typhus diagnosis, Scrub Typhus epidemiology
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- 2021
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48. Scrub typhus in Tierra del Fuego: a tropical rickettsiosis in a subantarctic region.
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Weitzel T, Aylwin M, Martínez-Valdebenito C, Acosta-Jamett G, and Abarca K
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- 2020
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49. Human seroepidemiology of Rickettsia and Orientia species in Chile - A cross-sectional study in five regions.
- Author
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Weitzel T, Acosta-Jamett G, Jiang J, Martínez-Valdebenito C, Farris CM, Richards AL, and Abarca K
- Subjects
- Adult, Aged, Aged, 80 and over, Chile epidemiology, Cross-Sectional Studies, Female, Humans, Male, Middle Aged, Prevalence, Rickettsia Infections epidemiology, Rickettsia Infections microbiology, Rickettsiaceae Infections microbiology, Scrub Typhus epidemiology, Scrub Typhus microbiology, Seroepidemiologic Studies, Young Adult, Orientia isolation & purification, Rickettsia isolation & purification, Rickettsiaceae Infections epidemiology, Rural Population statistics & numerical data, Urban Population statistics & numerical data
- Abstract
In recent years, the spectrum and epidemiology of human rickettsioses has become an emerging topic in Chile. This survey aimed to assess the seroprevalence of spotted fever group rickettsiae (SFGR), typhus group rickettsiae (TGR), and scrub typhus group orientiae (STGO) in northern, central, and southern Chile. We performed a cross-sectional study of healthy adults in rural and urban settings of five regions. Participants were chosen by double stratified random sampling in urban and by convenience in rural locations (n = 1302). Serum specimens were analyzed for group-specific IgG antibodies against SFGR, TGR, and STGO by enzyme-linked immunosorbent assays (ELISAs). Overall seroprevalences to SFGR, TGR, and STGO were 5.3 %, 1.2 %, and 0.4 %, respectively. Prevalences showed geographical differences. Statistical analyses revealed an association of older age with seropositivity to SFGR and to TGR and of rural setting and male gender with seropositivity to SFGR. The study indicates that SFGR, TGR, and STGO are endemic in Chile. The very low STGO seroprevalence might indicate an insufficient sensitivity of serological tests using Asian O. tsutsugamushi strains as ELISA antigens for the detection of antibodies against Chilean Orientia species., (Copyright © 2020 Elsevier GmbH. All rights reserved.)
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- 2020
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50. Safety and immunogenicity evaluation of recombinant BCG vaccine against respiratory syncytial virus in a randomized, double-blind, placebo-controlled phase I clinical trial.
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Abarca K, Rey-Jurado E, Muñoz-Durango N, Vázquez Y, Soto JA, Gálvez NMS, Valdés-Ferrada J, Iturriaga C, Urzúa M, Borzutzky A, Cerda J, Villarroel L, Madrid V, González PA, González-Aramundiz JV, Bueno SM, and Kalergis AM
- Abstract
Background: Respiratory syncytial virus (RSV) is responsible for most respiratory tract infections and hospitalizations in infants and represents a significant economic burden for public health. The development of a safe, effective, and affordable vaccine is a priority for the WHO., Methods: We conducted a double-blinded, escalating-dose phase 1 clinical trial in healthy males aged 18-50 years to evaluate safety, tolerability, and immunogenicity of a recombinant Mycobacterium bovis BCG vaccine expressing the nucleoprotein of RSV (rBCG-N-hRSV). Once inclusion criteria were met, volunteers were enrolled in three cohorts in an open and successive design. Each cohort included six volunteers vaccinated with 5 × 10
3 , 5 × 104 , or 1 × 105 CFU, as well as two volunteers vaccinated with the full dose of the standard BCG vaccine. This clinical trial (clinicaltrials.gov NCT03213405) was conducted in Santiago, Chile., Findings: The rBCG-N-RSV vaccine was safe, well-tolerated, and no serious adverse events related to the vaccine were recorded. Serum IgG-antibodies directed against Mycobacterium and the N-protein of RSV increased after vaccination, which were capable of neutralizing RSV in vitro . Additionally, all volunteers displayed increased cellular response consisting of IFN-γ and IL-2 production against PPD and the N-protein, starting at day 14 and 30 post-vaccination respectively., Interpretation: The rBCG-N-hRSV vaccine had a good safety profile and induced specific cellular and humoral responses., Funding: This work was supported by Millennium Institute on Immunology and Immunotherapy from Chile (P09/016), FONDECYT 1190830, and FONDEF D11E1098., Competing Interests: Authors KA, ERJ, NMD, YV, JS, NG, JV, CI, MU, AB, JC, VM, PG, JG, SB, and AMK report grants from Millennium Institute on Immunology and Immunotherapy from Chile, grants from Fondo Nacional de Desarrollo Científico y Tecnológico, grants from Fondo de Fomento al Desarrollo Tecnológico, personal fees from Pontificia Universidad Católica de Chile, during the conduct of the study. LV reports personal fees from Pontificia Universidad Católica de Chile, during the conduct of the study ., (© 2020 The Authors.)- Published
- 2020
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