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Dystrophic epidermolysis bullosa (DEB) is a clinically heterogeneous heritable skin disorder, characterized by blistering of the skin and mucous membranes following minor trauma. Dominant (DDEB) and recessive (RDEB) forms are caused by pathogenic variants in COL7A1 gene. Argentina's population has a heterogeneous genetic background, and little is known about the molecular basis of DEB in our country or in native South American populations. In this study, we present the prevalence and geographical distribution of pathogenic variants found in 181 patients from 136 unrelated families (31 DDEB and 105 RDEB). We detected 95 different variants, 59 of them were previously reported in the literature and 36 were novel, nine of which were detected in more than one family. The most prevalent pathogenic variants were identified in exon 73 in DDEB patients and in exon 3 in RDEB patients. We also report a new phenotype-genotype correlation found in 10 unrelated families presenting mild blistering and severe mucosal involvement. Molecular studies in populations with an unexplored genetic background like ours revealed a diversity of pathogenic variants, and we hope that these findings will contribute to the definition of targets for new gene therapies.

The community mitigation measures taken because of the COVID-19 pandemic had side effects on the circulation of the most frequent respiratory viruses during 2020. In the case of respiratory syncytial virus (RSV), an important paediatric pathogen, a decrease in the number of cases and delayed outbreaks was previously described.The genetic characteristics of the RSV circulating strains in paediatric patients in Buenos Aires, Argentina before and during the COVID-19 pandemic were studied. RSV (+) samples taken from hospitalised patients with respiratory tract infections (2018- 2021) were analysed through G gene sequencing and evolutionary analyses.No RSV hospitalised paediatric patients were registered in Buenos Aires during 2020; however, RSV reemerged in 2021 with a lower number of cases and a delayed outbreak, peaking in July-August. A total of 147 G gene sequences were analysed. RSV-B (N = 85) predominated during 2018 and 2021 whereas in 2019 RSV-A were more prevalent (N = 62). All RSV-A sequences were ON1-like strains, and all RSV-B were BA-like. Phylogenetic analyses showed that the same genetic lineages circulated before and after 2020, but RSVs from 2021 corresponded to new viral introductions rather than cryptic circulation of the previous genetic clusters in Buenos Aires during 2020.Following the reopening of borders, the reemergence of RSV in Argentina brought new viral introductions from other countries. Therefore, it is important to continue a deep global molecular surveillance to characterise RSV strains in post-pandemic circulation with an impact in future vaccine implementation.

Background: Respiratory syncytial virus is the leading cause of acute lower respiratory infection in children. We aimed to describe the clinical-epidemiologic pattern and risk factors for mortality associated with RSV infection. Methods: This is a prospective, cross-sectional study of acute lower respiratory infection in children admitted to the Children’s Hospital during 2000 to 2017. Viral diagnosis was made by fluorescent antibody techniques or real-time-polymerase chain reaction. We compared clinical-epidemiologic characteristics of RSV infection in nonfatal versus fatal cases. Multiple logistic regression was used to identify independent predictors of mortality. Results: Of 15,451 patients with acute lower respiratory infection, 13,033 were tested for respiratory viruses and 5831 (45%) were positive: RSV 81.3% (4738), influenza 7.6% (440), parainfluenza 6.9% (402) and adenovirus 4.3% (251). RSV had a seasonal epidemic pattern coinciding with months of lowest average temperature. RSV cases show a case fatality rate of 1.7% (82/4687). Fatal cases had a higher proportion of prematurity (P < 0.01), perinatal respiratory history (P < 0.01), malnourishment (P < 0.01), congenital heart disease (P < 0.01), chronic neurologic disease (P < 0.01) and pneumonia at clinical presentation (P = 0.014). No significant difference between genders was observed. Most deaths occurred among children who had complications: respiratory distress (80.5%), nosocomial infections (45.7%), sepsis (31.7%) and atelectasis (13.4%). Independent predictors of RSV mortality were moderate-to-severe malnourishment, odds ratio (OR): 3.69 [95% confidence interval (CI): 1.98–6.87; P < 0.0001]; chronic neurologic disease, OR: 4.14 (95% CI: 2.12–8.08; P < 0.0001); congenital heart disease, OR: 4.18 (95% CI: 2.39–7.32; P< 0.0001); and the age less than 6 months, OR: 1.99 (95% CI: 1.24–3.18; P = 0.004). Conclusions: RSV showed an epidemic pattern affecting mostly young children. Malnourishment, chronic neurologic disease, congenital heart disease and the age less than 6 months were the independent risk factors for RSV mortality. Fil: Gentile, Angela. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; Argentina Fil: Lucion, Maria Florencia. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; Argentina Fil: Juarez, Maria del Valle. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; Argentina Fil: Areso, María Soledad. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; Argentina Fil: Bakir, Julia. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; Argentina Fil: Viegas, Mariana. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez". Laboratorio de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Mistchenko, Alicia Susana. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez". Laboratorio de Virología; Argentina

Acute lower respiratory tract infection (ALRTI) caused by adenovirus is a major cause of morbidity and mortality in children.To describe the clinical and epidemiological pattern and associated factors in hospitalized children.Cross-sectional study in children admitted due to ALRTI to Hospital de Niños "Ricardo Gutiérrez," in the Autonomous City of Buenos Aires, between 2000 and 2018. Viral diagnosis was done by indirect immunofluorescence in nasopharyngeal secretions. The clinical and epidemiological characteristics of adenovirus infection were compared to other respiratory viruses (respiratory syncytial virus, influenza, and parainfluenza). A multiple logistic regression was done to identify independent predictors of infection.Out of 16 018 patients with ALRTI, 13 545 were tested for respiratory viruses; 6047 (45 %) had a positive result. Adenovirus was the least common agent (4.4 % [265] of cases); it tended towards a reduction over the study period (peak in 2003) and circulated throughout the year (peak in July). In total, 63.8 % of patients were males; median age: 11 months (interquartile range: 6-20). The most common clinical presentation was pneumonia (63 %). Prior admissions due to respiratory conditions were seen in 50 %; 15.6 % were readmissions; 58.3 % had comorbidities. Ventilatory support was required by 19.2 % and complications were recorded in 44 %. The fatality rate was 7.7 %. Adenovirus infection was associated with age ≥ 12 months, male sex, clinical presentation of pneumonia, prior admissions due to respiratory conditions, and readmissions.Adenoviruses were less common than other respiratory viruses, although their morbidity and mortality were important.Introducción. La infección respiratoria aguda baja por adenovirus es una importante causa de morbimortalidad en niños. Objetivos: Describir el patrón clínicoepidemiológico y los factores asociados en niños hospitalizados. Métodos. Estudio transversal en niños ingresados por infección respiratoria aguda baja al Hospital de Niños Ricardo Gutiérrez, Buenos Aires, en 2000-2018. El diagnóstico viral se realizó mediante inmunofluorescencia indirecta en secreciones nasofaríngeas. Se compararon características clínico-epidemiológicas de infección por adenovirus con otros virus respiratorios (virus sincicial respiratorio, influenza y parainfluenza). Se utilizó regresión logística múltiple para identificar predictores independientes de infección. Resultados. De 16018 pacientes con infección respiratoria aguda baja, 13545 fueron testeados para virus respiratorios y 6047 (el 45 %) fueron positivos. Adenovirus fue el agente menos frecuente [el 4,4 % (265) de los casos]; presentó una tendencia en descenso durante todo el período estudiado (pico en 2003) y circuló durante todo el año (pico en julio). El 63,8 % eran varones; mediana de edad: 11 meses (rango intercuartílico: 6-20). La presentación clínica más frecuente fue neumonía (el 63 %). El 50 % tenía internaciones previas por causa respiratoria; el 15,6 % eran reingresos; el 58,3 % tenía comorbilidades. El 19,2 % requirió asistencia ventilatoria; el 44 % registró complicaciones. La letalidad fue del 7,7 %. La infección por adenovirus se asoció a edad ≥ 12 meses, sexo masculino, presentación clínica de neumonía, internaciones previas por causas respiratorias y reinternaciones. Conclusiones. Los adenovirus fueron detectados con menor frecuencia que los otros virus respiratorios, aunque presentaron un importante perfil de morbimortalidad.

Group A rotaviruses (RVA) are the most frequent etiological agents causing severe diarrhea in infants and surveillance of genotype, and genetic characteristics of circulating strains are necessary in order to evaluate vaccine programs. The objectives of this work were to describe G and P genotype from 2012 through 2014 in Buenos Aires, Argentina completing an overview of 19 years of genotype surveillance in our region and to characterize an emerging G1P[8] strain associated with severe cases and five fatalities in 2014. We performed genotyping by RT-PCR. The sequencing of several genes, phylogenetic analyses, and comparative epidemiological data were used to know the origin and phylogenetic relationships of the emerging G1P[8] strain. Along with this report, 19 years of continuous RVA genotype surveillance in Argentina in the pre-vaccine era was covered. During the last year of this surveillance, 2014, a significantly increased incidence of RVA associated gastroenteritis was related to the reemergence of G1P[8] strains, being these ones detected in low frequency in the last nine years. Interestingly, the patients affected were significantly older when compared with those from the last six seasons. Additionally, phylogenetic analysis of several genes infer that these G1P[8] strains were closely related to Asian strains circulating during 2012 and 2013. In addition to this, the suggested extra continental origin for the 2014 G1P[8] strains and the very low circulation of G1 type during nine years probably explain the increased incidence and severity in the gastroenteritis cases and the particular epidemiologic characteristics. In conclusion, this work gives us a whole panorama of the pre-vaccine era of the RVA molecular epidemiology in the most populated region of Argentina. In this way, this work inspires us to continue with this type of studies in the post-vaccination era. Fil: Mandile, Marcelo Gastón. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Virologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Argüelles, Marcelo Horacio. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Virologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Temprana, Carlos Facundo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Virologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Peri Ibañez, Estefania Soledad. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Virologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Silvestre, Dalila. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Virologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Musto, Alejandra Beatriz. Gobierno de la Provincia de Buenos Aires. Hospital Provincial Evita Pueblo.; Argentina Fil: Rodríguez Pérez, Alberto. Hospital General de Agudos Dr. Alberto A. Eurnekian; Argentina Fil: Mistchenko, Alicia Susana. Gobierno de la Ciudad Autónoma de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez". Departamento de Medicina; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina Fil: Almallo de Glikmann, Graciela. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Virologia; Argentina Fil: Castello, Alejandro Andrés. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Virologia; Argentina. Universidad Nacional Arturo Jauretche; Argentina

Despite human parainfluenza type 3 viruses (HPIV3) are one of the leading causes of acute lower respiratory tract infections in children under five, there is no licensed vaccine and there is limited current information on the molecular characteristics of regional and global circulating strains. The aim of this study was to describe the molecular characterization of HPIV3 circulating in Buenos Aires. We performed a genetic and phylogenetic analysis of the HN glycoprotein gene. Between 2009 and 2013, 124 HPIV3 positive samples taken from hospitalized pediatric patients were analyzed. Four new genetic lineages were described. Among them, C1c and C3d lineages showed local circulation patterns, whereas C3e and C3f comprised sequences from very distant countries. Despite the diversity of the described genotypes, C3a and C3d predominated over the others, the latter was present during the first years of the study and it was progressively replaced by C3a. Molecular analyses showed 28 non-synonymous substitutions, of these 13 were located in potentially predicted B-cell epitopes. Taking together, the emergence of genetic lineages and the information of the molecular characteristics of HN protein may contribute to the general knowledge of HPIV3 molecular epidemiology for future vaccine development and antiviral therapies. Fil: Goya, Stephanie. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños ; Argentina Fil: Mistchenko, Alicia Susana. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños ; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina Fil: Viegas, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños ; Argentina

Dengue is the human arbovirus with the highest morbidity and mortality in the world. The largest outbreak of dengue in Buenos Aires, Argentina, occurred during 2016.To describe clinical and hematological features in children with confirmed dengue infection.Cross sectional study that included children attended since January 18th to April 15th 2016 at Hospital de Niños "Dr. Ricardo Gutiérrez".among 156 registered cases, 82 confirmed cases by virology test; 130 (83 %) autochthonous cases. The most frequent clinical manifestations were fever, headache and retro-ocular pain. Laboratory abnormalities were leukopenia, thrombocytopenia and increased liver enzymes. Thirty-five children were hospitalized (23 %), 25 (16 %) with warning signs. In our study, no cases of severe dengue occurred.early recognition of warning signs and hematological monitoring is essential in order to detect patients at risk and offer them adequate early treatment.El dengue es la arbovirosis humana que más morbimortalidad ocasiona mundialmente. Durante 2016, se registró, en la Ciudad de Buenos Aires, Argentina, la mayor epidemia de esta enfermedad. Objetivo: describir las características clínicas y hematológicas en una población pediátrica. Métodos: estudio de corte transversal que incluyó a pacientes atendidos del 18-1-16 al 15-4-16 en el Hospital de Niños "Dr. Ricardo Gutiérrez". Resultados: se registraron 156 casos, 82 confirmados por virología; 130 (83 %), autóctonos. Las manifestaciones clínicas más frecuentes fueron fiebre, cefalea y dolor retroocular. Las alteraciones del laboratorio significativas fueron leucopenia, plaquetopenia y aumento de transaminasas. Se internaron 35 pacientes (23 %), 25 (16 %) con signos de alarma. No se presentó ningún caso de dengue grave. Conclusiones: el reconocimiento oportuno de los signos de alarma y el control hematológico resultan fundamentales para detectar a los niños en riesgo y ofrecerles tratamiento de soporte en forma precoz.

Background Influenza is an important cause of acute lower respiratory tract infection (aLRTI), hospitalization, and mortality in children. This study aimed to describe the clinical and epidemiologic patterns and infection factors associated with influenza, and compare case features of influenza A and B. Methods In a prospective, cross-sectional study, patients admitted for aLRTI, between 2000 and 2015, were tested for respiratory syncytial virus, adenovirus, influenza, or parainfluenza, and confirmed by fluorescent antibody (FA) or real-time polymerase chain reaction (RT-PCR) assay of nasopharyngeal aspirates. Results Of 14,044 patients, 37.7% (5290) had FA- or RT-PCR-confirmed samples that identified influenza in 2.8% (394/14,044; 91.4% [360] influenza A, 8.6% [34] influenza B) of cases. Influenza frequency followed a seasonal epidemic pattern (May–July, the lowest average temperature months). The median age of cases was 12 months (interquartile range: 6–21 months); 56.1% (221/394) of cases were male. Consolidated pneumonia was the most frequent clinical presentation (56.9%; 224/394). Roughly half (49.7%; 196/394) of all cases had previous respiratory admissions; 9.4% (37/394) were re-admissions; 61.5% (241/392) had comorbidities; 26.2% (102/389) had complications; 7.8% (30/384) had nosocomial infections. The average case fatality rate was 2.1% (8/389). Chronic neurologic disease was significantly higher in influenza B cases compared to influenza A cases (p = 0.030). The independent predictors for influenza were: age 6 months, odds ratio (OR): 1.88 (95% confidence interval [CI]: 1.44–2.45); p

Human respiratory syncytial virus (HRSV) is the main viral cause of acute lower respiratory tract infections (LRTI) in children worldwide. In recent years, several preclinical trials with vaccine candidates have been reported. It is in this sense that molecular epidemiological studies become important. Understanding viral dispersion patterns before and after the implementation of a vaccine can provide insight into the effectiveness of the control strategies. In this work we analyzed the molecular epidemiology of HRSV-A over a period of sixteen years (1999-2014) in Buenos Aires. By bioinformatic tools we analyzed 169 sequences of the G glycoprotein gene from hospitalized pediatric patients with LRTI. We found that GA2 was the most prevalent genotype (73.35%). GA5 genotype co-circulated in our region until 2009 when it was no longer detected, except in 2011. The recently globally emerging ON1 lineage with a 72-nt duplication increased its frequency to become the only lineage detected in Buenos Aires in 2014. By discrete phylogeographic analysis of global ON1 strains we could determine that Panama could be the location of the MRCA dated June 20, 2010; and this lineage could be introduced in Argentina from Spain in April 2011. This analysis also showed temporary and geographical clustering of ON1 strains observed as phylogenetic clades with strains exclusively associated from a single country, nevertheless among our 44 ON1 strains from three outbreaks (2012-2014) we could also detect posterior reintroductions and circulation from United States, Cuba, South Korea, and Spain. The continuous phylogeographic analysis of one sublineage of Argentine ON1 strains allowed us to establish that there could be a local clustering of some strains even in neighborhoods. This work shows the potential of this type of bioinformatic tools in the context of a future vaccine surveillance network to trace the spread of new genetic lineages in human populations. Fil: Viegas, Mariana. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez". Laboratorio de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Goya, Stephanie. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez". Laboratorio de Virología; Argentina Fil: Mistchenko, Alicia Susana. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez". Laboratorio de Virología; Argentina

Background The human adenovirus (HAdV) types most commonly found in respiratory samples belong to HAdV species C (HAdV-C1, -C2, -C5, and -C6) and to HAdV species B (HAdV-B3 and -B7). Several studies in South America have shown the association between severe respiratory infections and subspecies B1. Objectives The aim of this study was to identify the adenovirus types associated with acute lower respiratory tract infections in children, found as single or coinfections, throughout a 12-year period. Study design All samples that tested positive for adenovirus by immunofluorescence assay from January 1999 to December 2010 were typed by evaluating a set of four viral genes (E1A, VA, hexon and fiber). Quantitative PCRs for HAdV-B and HAdV-C species were performed to compare the viral load found in single infections and coinfections. Results From a total of 743 HAdV, 654 (88%) were single infections and 89 (12%) coinfections. From the 654 single HAdV infections, members of four species were present: species B ( n = 492, 75.23%), species C ( n = 138, 21.1%), species E ( n = 19, 2.91%), and species D ( n = 5, 0.76%). Only members of species B ( n = 109, 57.67%) and species C ( n = 80, 42.33%) were detected in coinfections. HAdV-B7 and HAdV-B3 were the most prevalent types ( n = 308, 36.54%; n = 230, 27.28% respectively) and HAdV-C1, -C2, -E4, -C5, -C6, -D8, -B11, -B14 and -B21 were also detected. Viral loads for species C viruses were higher in single infections than in coinfections ( p p Conclusions This study provides a thorough description of adenovirus circulation and diversity in Buenos Aires in a 12-year period. The high proportion of coinfections found in this work shows that this phenomenom might be more common than expected.

An influenza pandemic caused by swine-origin influenza virus A/H1N1 (H1N1pdm) spread worldwide in 2009, with 12,080 confirmed cases and 626 deaths occurring in Argentina. A total of 330 H1N1pdm viruses were detected from May to August 2009, and phylogenetic and genetic analyses of 21 complete genome sequences from both mild and fatal cases were achieved with reference to concatenated whole genomes. In addition, the analysis of another 16 hemagglutinin (HA), neuraminidase (NA), and matrix (M) gene sequences of Argentinean isolates was performed. The microevolution timeline was assessed and resistance monitoring of an NA fragment from 228 samples throughout the 2009 pandemic peak was performed by sequencing and pyrosequencing. We also assessed the viral growth kinetics for samples with replacements at the genomic level or special clinical features. In this study, we found by Bayesian inference that the Argentinean complete genome sequences clustered with globally distributed clade 7 sequences. The HA sequences were related to samples from the northern hemisphere autumn-winter from September to December 2009. The NA of Argentinean sequences belonged to the New York group. The N-4 fragment as well as the hierarchical clustering of samples showed that a consensus sequence prevailed in time but also that different variants, including five H275Y oseltamivir-resistant strains, arose from May to August 2009. Fatal and oseltamivir-resistant isolates had impaired growth and a small plaque phenotype compared to oseltamivir-sensitive and consensus strains. Although these strains might not be fit enough to spread in the entire population, molecular surveillance proved to be essential to monitor resistance and viral dynamics in our country.

Background Pandemic influenza A H1N1 2009 virus presents a new challenge to health authorities and communities worldwide. In Argentina, the outbreak was at its peak by the end of June 2009, during the southern winter. A systematic analysis of samples from patients with pandemic H1N1 2009 studied in our laboratory (Virology Laboratory, Hospital de Niños R Gutiérrez, Buenos Aires, Argentina) detected two patients presenting intratreatment emergence of the H275Y neuraminidase mutation, which confers resistance to oseltamivir. Methods Complementary DNAs, including the 275 codon, were obtained by reverse transcriptase PCR using viral RNAs extracted from nasopharyngeal or tracheal aspirates. Conventional sequencing and pyrosequencing were performed on each sample. In order to measure the virus susceptibility to oseltamivir, 50% inhibitory concentration determinations were performed by chemiluminescence. Results Sequential samples of two paediatric patients under oseltamivir treatment were analysed. Pretreatment samples were composed of 100% oseltamivir-sensitive variants. In case 1, the oseltamivir-resistant variant was found 8 days after the beginning of treatment. In case 2, the viral population became resistant on the second day of treatment, with 83% of the viral population bearing the mutation and this reached 100% on the seventh day. Conclusions We describe the intratreatment emergence of oseltamivir resistance in two paediatric patients. Pyrosequencing allowed us to detect variant mixtures, showing the transition of the viral population from sensitive to resistant.

Dengue virus as a member of mosquito-borne flaviviruses is responsible for an increasing number of human infections worldwide, mainly in tropical and subtropical urban areas. The agent, a single-stranded positive sense RNA virus, is comprised of four serotypes and genetic variation within each serotype can be further divided into different genotypes. Dengue outbreaks were reported in bordering countries during the last years; the latest reported in Paraguay in 2006-2007. In Buenos Aires, 32 dengue cases were confirmed in travelers coming from this country by anti-dengue IgM antibodies detection, RT-PCR and/or isolation in C6/36 cell line. Structural proteins C, prM/M, E and non-structural proteins 1 and 2 from eight viruses were genetically characterized. Phylogenetic inference was performed for the E-protein and all viruses clustered with dengue virus 3 Genotype III. This is the first report of genetic characterization of dengue virus 3 in Argentina.

BACKGROUND: Long-term seroprotection data are essential for decision-making on the need and timing of vaccine boosters. Based on data from longitudinal serological studies, modeling can provide estimates on long-term antibody persistence and inform such decision-making. METHODS: We examined long-term anti-hepatitis A virus (anti-HAV) antibody persistence in Argentinean children ≤15 years after the initial study where they completed a 2-dose course of inactivated hepatitis A vaccine (Avaxim 80U Pediatric, Sanofi Pasteur, Lyon, France). Blood serum samples were taken at baseline, 2 weeks (post first dose), 6 months (pre-booster), 6.5 months (post-booster), 10 years and 14-15 years after first vaccine dose. We fitted 8 statistical model types, predominantly mixed effects models, to anti-HAV persistence data, to identify the most appropriate and best fitting models for our data set and to predict individuals' anti-HAV levels and seroprotection rates up to 30 years post vaccination. RESULTS: Fifty-four children (mean age at enrollment 30.4 months) were enrolled up to 15 years post first vaccine dose. There were 3 distinct periods of antibody concentration: rapid rise up to peak concentration post-booster, rapid decay from post-booster to 10 years, followed by slower decay. A 3-segmented linear mixed effects model was the most appropriate for the data set. Extrapolating based on the available 14-15-year follow-up, the analysis predicted that 88% of individuals anti-HAV seronegative prior to vaccination would remain seroprotected at 30 years post vaccination and lifelong seroprotection for vaccinees seropositive prior to vaccination. CONCLUSIONS: Currently available data demonstrate that Avaxim 80U Pediatric confers to most vaccinees a high level of seroprotection against hepatitis A infection for at least 20-30 years.

During the winter months there is a remarkable increase in paediatric hospitalisations due to viral acute lower respiratory infections (ALRI). We aimed to perform a five-year retrospective analysis (1998-2002) of ALRI viral aetiology in children under 5 years of age admitted to public hospitals in Buenos Aires city to evaluate its seasonality.Nasopharyngeal aspirates (NPA) were analysed by indirect immunofluorescence to determine viral aetiology. A Spearman's rank correlation test between meteorological parameters and viral frequencies was performed.Viruses were identified in 6083 (32.8%) of 18,561 NPA tested. Among the former 4796 (78.8%) were RSV, 508 (8.3%) IA, 473 (7.8%) AV, 293 (4.8%) PIV and 13 (0.2%) IB. RSV and IA peaked during the coldest and dampest months, whereas PIV did so in early spring and AV lasted throughout the year. For RSV and IA an inverse correlation with mean monthly temperature (r = -0.9 and r = -0.87, respectively, p0.0001) and solar UVB radiation (r = -0.92 and r = -0.80, respectively, p0.0001) was detected, while it was positive when relative humidity was considered (r = 0.6, p0.0001 and r = 0.47, p=0.0068, respectively).This study highlights the seasonal variation of ALRI and allows the implementation of adequate healthcare strategies and practice guidelines.

Dengue (DEN) constitutes a major viral arthropod-borne human illness. South America was last considered free of dengue two decades ago when a dramatic increase in the number of dengue fever and hemorrhagic dengue cases had been reported. Five viruses were isolated in Buenos Aires City from the 1999–2000 Paraguay outbreak. RT-PCRs obtained directly from plasma were cloned into pGemT vectors and sequences of the structural genes and NS1 were analyzed. Three viruses were full-length sequenced from RT-PCR obtained from cell-culture isolates. Excess of synonymous over non-synonymous mutations suggested that the structural proteins were under strong functional constraints while a weak purifying selection was operating in the whole polyprotein. Sequence diversity and selective pressures varied among patients but results were significantly above the procedure threshold. One sample showed small-plaque phenotype and impaired growth coupled to 3′untranslated region mutations. Phylogenetic analysis of full-length sequences split Buenos Aires isolates into two clusters within American DEN-1 genotype V: Clade I was phylogenetically linked to Brazilian samples and Clade II with samples from Paraguay and Northeastern Argentina. In Buenos Aires City, only dengue virus serotype 1 imported from Paraguay has been detected, though without evidence of local transmission.

We studied eight children who had measles at 6 to 10 months of age during the 1998 Argentine measles outbreak and in whom subacute sclerosing panencephalitis developed 4 years later. We report the genetic characterization of brain tissue–associated measles virus samples from three patients. Phylogenetic relationships clustered these viruses with the wild-type D6 genotype isolated during the 1998 outbreak. The children received measles vaccine; however, vaccinal strains were not found.

Dengue virus (DENV) is a public health problem representing the most important arthropod-borne viral disease in humans. In Argentina, Northern provinces have reported autochthonous cases since 1997, though these outbreaks have originated in bordering countries, where co-circulation of more than one serotype has been reported. In the last decade, imported dengue cases have been reported in Buenos Aires, the urban area of Argentina with the highest population density. In 2009, a dengue outbreak affected Buenos Aires and, for the first time, local transmission was detected. All cases of this outbreak were caused by DENV-1. In this report, we present the full-length sequences of 27 DENV-1 isolates, corresponding to imported cases of 1999–2000, as well as local and imported cases of the 2009 and 2010 outbreaks. We analyzed their phylogenetic and phylodynamic relationships and their global and local spread. Additionally, we characterized their genomic and phenotypic features. All cases belonged to DENV-1 genotype V. The most recent ancestor for this genotype was dated ∼1934, whereas that for the 2009 outbreak was dated ∼2007. The mean rates of nucleotide substitution were 4.98E-4 and 8.53E-4 subs./site/yr, respectively. We inferred an introduction from Paraguay in 1999–2000 and mainly from Venezuela during 2009–2010. Overall, the number of synonymous substitutions per synonymous site significantly exceeded the number of non-synonymous substitutions per site and 12 positively selected sites were detected. These analyses could contribute to a better understanding regarding spread and evolution of this pathogen in the Southern Cone of South America. Fil: Tittarelli, Estefanía. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez". Laboratorio de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Mistchenko, Alicia Susana. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez". Laboratorio de Virología; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina Fil: Barrero, Paola Roxana. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez". Laboratorio de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Nucleoprotein (N) and Haemagglutinin (H) genes from measles viruses isolated from Argentina before and after the 1993 and 1998 massive vaccination campaigns were characterised to determine genetic variations that occurred from 1991 to 1999. Measles viruses from the 1991-94 period were clustered with the C1 genotype and those from 1997-99 with D6. Genetic variations within the 1997-99 outbreak were less than 1.2% and 0.79% for the N and H sequences respectively. The C1 genotype has not been detected since 1994 and the finding that a single D6 virus was found in November 1999 demonstrates that wild type viruses are still circulating among a partially covered population.

We examined long-term anti-hepatitis A virus antibody persistence in Argentinean children 10 years after the initial study in which they received 2 doses of inactivated hepatitis A vaccine (Avaxim 80U). Of the 111 children, 48 from the initial trial were enrolled. Of 48, 47 (97.9%) participants had serum anti-hepatitis A virus antibody titers > or =20 mIU/mL, with the geometric mean concentration of 390.91 (+/-370.14) mIU/mL; (95% confidence interval, 282.2-499.5 mIU/mL), range, 36 to 1860.

The frequency of respiratory syncytial virus (RSV) and the distribution of subgroups A and B strains during 7 consecutive years (1990-1996) were examined in two cities of Argentina. Nasopharyngeal aspirates from 1,304 children less than 2 years of age hospitalized with acute lower respiratory infection were studied by indirect immunofluorescence. RSV was detected in 352 cases (26.9%), and the peak activity was observed in midwinter. Subgroup characterization was performed with two monoclonal antibodies against the F protein on nasopharyngeal aspirate smears. Of 195 samples, 174 (89.2%) were identified as subgroup A strains and 21 (10.8%) as subgroup B. Both strains cocirculated during 5 of 7 years studied with subgroup A predominating. Subgroup A occurred at least 8 times as often in all years except for 1994-1995. Children infected by subgroup A were younger than those infected by subgroup B (P < 0.05). The association of subgroup A infection with bronchiolitis and subgroup B with pneumonia was statistically significant (P < 0.03).

Epidemiological and clinical findings from 1162 serologically confirmed measles cases occurring in Buenos Aires, Argentina in 1997 and 1998 were retrospectively reviewed. From 90 hospitalized children, measles virus was detected by direct RT–PCR from nasopharyngeal secretions. Patients were grouped as follows: (i) not vaccinated: infants < 12 months; (ii) regularly vaccinated: children 1–4 years not covered by the last catch-up; (iii) catch-up vaccinated: patients 5–19 years immunized during the 1993 campaign. Most cases were recorded in non-vaccinated infants (54%), and the lowest in catch-up vaccinated children (16%). Mean age of the 90 hospitalized children was 11·3 months. Pneumonia was the major hospitalization cause followed by pneumonitis. Two children required intensive care and one died. The 1993 catch-up campaign seemed to reduce the number of cases in the 5- to 19-year-old group. Lack of timely follow-up probably led to the accumulation of susceptible individuals allowing measles re-emergence. Direct viral detection by RT–PCR proved to be a sensitive tool for molecular epidemiology surveillance.

Human metapneumovirus, which belongs to the Paramyxoviridae family and has been classified as a member of the Pneumovirus genus, is genetically and clinically similar to other family members such as human respiratory syncytial virus. A total of 1146 nasopharyngeal aspirates from pediatric patients with moderate and severe acute lower respiratory tract infections, hospitalized at the Ricardo Gutierrez Childreńs Hospital (Buenos Aires, Argentina), were tested by real time RT-PCR for human metapneumovirus. Results showed that 168 (14.65%) were positive. Thirty-six of these 168 samples were randomly selected to characterize positive cases molecularly. The phylogenetic analysis of the sequences of the G and F genes showed that genotypes A2 and B2 cocirculated during 2009 and 2010 and that only genotype A2 circulated in 2011 in Argentina. Genotype A2 prevailed during the study period, a fact supported by a higher effective population size (Neτ) and higher diversity as compared to that of genotype B2 (10.9% (SE 1.3%) vs. 1.7% (SE 0.4%), respectively). The phylogeographic analysis of the G protein gene sequences showed that this virus has no geographical restrictions and can travel globally harbored in hosts. The selection pressure analysis of the F protein showed that although this protein has regions with polymorphisms, it has vast structural and functional constraints. In addition, the predicted B-linear epitopes and the sites recognized by previously described monoclonal antibodies were conserved in all Argentine sequences. This points out this protein as a potential candidate to be the target of future humanized antibodies or vaccines. Fil: Velez Rueda, Ana Julia. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez". Laboratorio de Virología; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Mistchenko, Alicia Susana. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez". Laboratorio de Virología; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Viegas, Mariana. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez". Laboratorio de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

s u m m a r y We report two cases of St. Louis encephalitis where the virus was detected in patients’ sera directly by molecular techniques allowing subsequent typing. Phylogenetic analysis of both samples showed that NS5 sequences clustered with viruses previously classified as genotype III.

SUMMARYTo examine the role of enteric adenoviruses (EAV) in an urban area of Buenos Aires (Argentina), we prospectively studied faecal samples from 49 families of newborns. These were monitored weekly for diarrhoea for 2 years.A total of 180 samples from cases of diarrhoea and 766 samples obtained during diarrhoea-free periods were studied by dot-blot hybridization with an EAV-specific DNA probe. EAV were found in 6/180 (3·3%) cases of diarrhoea and 6/766 (0·8%) asymptomatic samples (P < 0·015). Incidence of EAV was 3·9 cases per 100 person-years in children < 60 months old. EAV-related diarrhoeas were slight and of short duration. In addition, 129 faeces from hospital out-patients, 1–30 months old, were also studied. EAV was identified in 7/129 cases (5·4%). These cases were 9·5 ±3·5 months old and the diarrhoea was mild or severe, of 3±1·5 days of duration.We suggest that EAV are low-risk causes of diarrhoea under natural conditions, although a few children may develop more severe diarrhoea. The diagnosis of EAV needs to be considered in these patients.

Background A rubella outbreak was recorded in Buenos Aires during 2008. Objectives The objective of this communication is to present the genetic and phylogenetic analyses of wild-type RUBV circulating in Buenos Aires during the 2008 outbreak. Study design Throat swab samples collected from patients diagnosed with rubella between June 2008 and December 2008 were inoculated in cell culture and 23 isolates were sequenced. Results Phylogenetic analysis of the WHO-recommended window (nt 8731–9469) of the E1 envelope glycoprotein was performed and all isolates clustered with the 2B genotype. Conclusions Genotype 2B seems to be endemically circulating in the Southern cone of Latin America, thus causing recent outbreaks.

Background Human enteroviruses are one of the major causes of central nervous system (CNS) infections in pediatrics. Study design We have studied 1242 children under 15 years old with suspicion of CNS infection from January 1998 to December 2003. CSF was obtained and molecular typing of human enterovirus B serotypes was performed by RT-PCR and sequencing of the N-terminal part of VP1 gene. Results According to the clinical syndromes, patients were grouped as aseptic meningitis ( n = 654, 52.6%), encephalitis ( n = 239, 19.2%), febrile seizures ( n = 153, 12.3%), febrile infant ( n = 84, 6.7%), neonatal disease ( n = 70, 5.6%),), acute flaccid paralysis ( n = 31, 2.4%) and acute disseminated encephalomyelitis ( n = 11, 0.9%). HEV was detected in 335/1242 CSF samples (26.97%) and was associated to aseptic meningitis ( n = 243, 72.5%); febrile infant ( n = 31, 9.2%); neonatal infection ( n = 26, 7.7%); encephalitis ( n = 25, 7.5%), febrile seizures ( n = 9, 2.68%); acute flaccid paralysis ( n = 1, 0.3%). Seasonal incidence of HEV-B species was analyzed showing that in Buenos Aires infections occur mainly during late spring and summer. Molecular serotyping was completed in 60/335 samples. Echovirus 30, Echovirus 9, Coxsackie B3 to B5 and Echovirus 33 were the most frequently identified. Conclusions We showed that HEV are responsible for a considerable proportion of hospitalizations in children with central nervous system compromise reaching 27% of overall etiology.

A total of 47 clinical samples were identified during an active surveillance program of respiratory infections in Buenos Aires (BA) (1999 to 2004) that contained sequences of human respiratory syncytial virus (HRSV) with a 60-nucleotide duplication in the attachment (G) protein gene. This duplication was analogous to that previously described for other three viruses also isolated in Buenos Aires in 1999 (A. Trento et al., J. Gen. Virol. 84:3115-3120, 2003). Phylogenetic analysis indicated that BA sequences with that duplication shared a common ancestor (dated about 1998) with other HRSV G sequences reported worldwide after 1999. The duplicated nucleotide sequence was an exact copy of the preceding 60 nucleotides in early viruses, but both copies of the duplicated segment accumulated nucleotide substitutions in more recent viruses at a rate apparently higher than in other regions of the G protein gene. The evolution of the viruses with the duplicated G segment apparently followed the overall evolutionary pattern previously described for HRSV, and this genotype has replaced other prevailing antigenic group B genotypes in Buenos Aires and other places. Thus, the duplicated segment represents a natural tag that can be used to track the dissemination and evolution of HRSV in an unprecedented setting. We have taken advantage of this situation to reexamine the molecular epidemiology of HRSV and to explore the natural history of this important human pathogen.

Sequence analysis was performed on 50 measles viruses (MV) isolated in Argentina. Forty-six were obtained during the current outbreak (1997-1998), three from the previous outbreak (1991) and one sporadic case (1994). A 377-bp fragment of the hemagglutinin (H) gene was directly amplified by RT-PCR from nasopharyngeal secretions. Nucleotides 8152 to 8417 were sequenced and subjected to phylogenetic analysis. Multiple silent changes and point mutations were found in all MVs. In 1991, substitutions affected the third base in codons resulting in silent changes. In 1994 an A--C substitution at position 8321 changed amino acids 351 (Leu--Ile). In 1997-1998, an A--G substitution at position 8339 changed amino acids 357 (Val--Ile). In 3/46 viruses, guanine deletion at position 8205 changed the reading frame and insertion of an extra cytosine at nucleotide 8235 shifted it back to the original frame. Phylogenetic analysis revealed that viruses leading to the last two major outbreaks are clustered into two separate branches. MVs that prevailed until 1994 were related to genotype C1 and MVs of the current outbreak to D6. Random drift mutations rendered a 0.5 ratio of nonsilent over silent mutations in most of the MVs analyzed. However, in those showing a reading frame shift, the ratio was greater than 1, suggesting that it was driven by immune selection.

A collection of 165 adenovirus strains isolated from nasopharyngeal aspirates of children hospitalized for acute lower respiratory infection in Argentina, Chile, and Uruguay between 1991 and 1994 was studied by restriction enzyme analysis (work performed in the Department of Virology, University of Umeå). Of the isolates, 71% (n = 117) were identified as members of subgenus B. Of these, 101 (61.2%) corresponded to genome type 7h, four (2.4%) to genome type 3p2, four (2.4%) to genome type 11a, one (0.6%) to genome type 7b, and one (0.6%) to genome type 7c. Two isolates that were neutralized as serotype 3 and four isolates that were neutralized as serotype 7 exhibited novel BamHI cleavage profiles corresponding to three new genome types denominated 3x, 7i, and 7j. Subgenus C members represented 28.5% of all typed isolates. Five different genome types of Ad1, seven genome types of Ad2, and three genome types of Ad5 were identified of, which two, two, and one, respectively, were found to correspond to new DNA variants. Only one isolate (0.6%) corresponded to Ad4 of subgenus E. Ad7h was isolated from 17 of the 18 fatal cases recorded among the patients included in the study.