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Objective To identify the arbovirus involved in febrile cases identified in a pediatric clinic in Cali, Valle del Cauca province, Colombia, and study the clinical characteristics. Methods A descriptive, prospective study enrolled 345 febrile children for 12 months in a pediatric clinic. Medical record registers documenting signs and symptoms, and serum samples were analyzed to detect DENV, CHIKV, and ZIKV by reverse transcription-polymerase chain reaction and serology methods. Diagnosis at the time of admission and discharge were compared based on laboratory test results. Results All patients were diagnosed as severe dengue at admission. Molecular detection and serology tests identified 143 CHIKV-positive (41.4%), 20 DENV-positive (5.8%), and 123 DENV-CHIKV coinfection patients (35.7%). DENV or CHIKV serology test results of these double-infected patients yield poor performance to confirm patient cases. ZIKV infection was detected in 5 patients (1.4%), every time as double or triple infections. Conclusion . A sustained CHIKV circulation and transmission was confirmed causing febrile illness in children and indicating that this virus spreads even during the regular DENV season, leading to double infections and altering clinical symptoms. Specific clinical tests are necessary to closely identify the arbovirus involved in causing infectious diseases that can help in better treatment and mosquito-transmitted virus surveillance.

Data in this article are associated with our research article “Dental Resin Monomers Induce Early and Potent Oxidative Damage on Human Odontoblast-like Cells.” Dental adhesives are polymeric compounds consisting of several chemical substances, including resin monomers, such as 2-hydroxyethyl methacrylate (HEMA) and triethylene glycol dimethacrylate (TEGDMA), together with other comonomers, making up the organic matrix of the adhesive and whose composition is based on the methyl methacrylate chemistry. The release of residual monomers, susceptible to biodegradation, acts as a source of bioactive compounds, which can interact with tissues and induce a cytotoxic cellular response. The most used techniques to evaluate cytotoxicity, proliferation, or metabolic activity of cells exposed to different substances, are MTT and resazurin. Each chemistry evaluates cell viability differently, so the data obtained could vary depending on the technique sensitivity to detect changes in cell metabolism. The objective of this article was to present viability data as a function of the metabolic activity in human odontoblast-like cells (hOLCs), exposed to 3, 6, 9, and 12 mM HEMA, or 0.75, 1.5, 3, and 6 mM TEGDMA evaluated by the MTT, and resazurin techniques in the first 24 hours of exposure, at different time points. The absorbance data for the MTT test and the fluorescence intensity for the resazurin test were obtained by spectrometry. SIMSTAT software 2.6.5 for Windows was used to confirm the normal data distribution (Levene's test). Subsequently, an analysis of variance (one-way ANOVA) was performed to compare the control with each HEMA and TEGDMA concentration. Where a p < 0.05 indicated a high F value, a Fisher's least significant differences post-hoc analysis was performed, using an alpha value < 0.05. Data from the different time points were compared with a Student's t-test for each concentration. These data may be useful to compare the cytotoxic response of hOLCs with other cell types or the cell response to other resin monomers.

El virus Herpes simplex tipo 1 (HSV-1) es el principal causante de infecciones virales en la mucosa oral y regiones periorales. Esta infección es seguida por la diseminación del virus a neuronas sensoriales del ganglio trigeminal donde establece una infección latente de por vida. Se ha descrito que la respuesta inmune es importante para el control de la infección por HSV-1 y para el establecimiento de infecciones en el ganglio trigeminal. Sin embargo, no se conoce totalmente el papel de la respuesta inmune innata, en especial la de los Interferones (IFNs), frente al HSV-1 en el ganglio trigeminal. Por esto, se propuso indagar el papel del IFN-β ante a la infección por HSV1 en cultivos primarios de ganglio trigeminal de ratón. Así como evidenciar la expresión de genes inducidos por IFN en estas células tras la infección por HSV-1 y tras el tratamiento con IFN. Al mismo tiempo, evaluar la activación de la cascada de señalización Jak-Stat activada por IFN-β en cultivos de GT infectados con HSV-1. Se evidenció que el IFN-β tiene un efecto antiviral frente al HSV-1 en cultivos primarios de GT murino, causando una inhibición transcripcional de los 3 tipos de genes virales del ciclo lítico del virus, disminuyendo la producción de partículas virales y evitando la muerte celular por el virus. Adicionalmente la infección con HSV-1 incrementó los transcritos de Oligoadenilato sintetasa-1a y Rnasa L. El tratamiento con IFN-β causó la sobre-expresión de los genes de la Proteína kinasa R y Oligoadenilato sintetasa-1a; indicando que la actividad antiviral del IFN-β puede estar mediada por estas moléculas. Además, la infección disminuyó significativamente los niveles constitutivos del gen de la Proteína kinasa R, que participa en la inhibición traduccional mediada por IFN. Lo cual podría indicar que en el ganglio trigeminal ocurre un mecanismo nuevo de evasión viral al IFN, que hasta el momento no había sido descrito. Asimismo, la infección por HSV-1 causó la inducción del gen del Supresor de Señalización de Citoquinas-3 relacionado con el apagamiento de la señal del IFN-β, pero esta inducción disminuyó con el pre-tratamiento con IFN-β. Finalmente se evidenció que la infección con HSV-1 inhibió parcialmente la activación de la cascada de señalización Jak-Stat inducida por IFN-β, lo cual también podría representar un nuevo mecanismo de evasión viral que ocurre en el GT durante la etapa de infección aguda. Estos mecanismos virales de regulación de la respuesta inducida por IFN, que no han sido reportados previamente en ganglio trigeminal, podrían permitirle al HSV-1 establecer infecciones agudas de forma más eficiente, al contrarrestar parcialmente la respuesta inmune innata mediada por IFN-β en el GT y favorecer la instauración de la latencia. Magíster en Ciencias Básicas Biomédicas Maestría Herpes simplex virus type 1 (HSV-1) is the main pathogen that causes viral infections in oral mucosa and perioral regions. This is followed by viral diffusion through the sensory neurons in trigeminal ganglion, where it establishes life-long latent infections. It has been described that immune response is important to control HSV-1 infections and estalishment of latency. However, it is not well known completely, the role of innate immune response, especially the role mediated by Interferons (IFNs), against HSV-1 infections in trigeminal ganglia. For all these, we aimed to dig into the IFN-β role against HSV-1 infection in mice trigeminal ganglion primary cultures. To evaluate IFN stimulated gene expression, in these cells after HSV-1 infection or IFN-β treatment. Besides, we aim to evaluate activation of IFN-β Jak-Stat signal transduction in trigeminal ganglion cultures after HSV-1 infection. It was observed that IFN-β exerts an antiviral effect against HSV-1 in trigeminal ganglion cultures that causes transcripcional inhibition of viral lytic genes decreasing virions production and impairing cell death induced by viral infection. Additionally, HSV-1 infection increased Oligoadenylate synthetase-1a y Rnase L mRNA; and IFN-β treatment caused Oligoadenylate synthetase-1a and Protein kinase R induction, which implies that IFN-β antiviral activity may occur through these molecules. Besides infection significantly decreased constitutive levels Protein kinase R gene, that causes translational inhibition after IFN treatment. This could suggest that in trigeminal ganglia, a viral evasion mechanism exists that has not been described previously. Furthermore, HSV-1 infection caused Suppresor of Cytokine signalling-3 gene upregulation, which is related to IFN negative feedback. But this induction decreased after IFN-β pre-treatment. Finally HSV-1 infection partially inhibited IFN Jak-Stat pathway after infection. This also could be a novel viral evasion mechanism that occurs in trigeminal ganglion during acute herpes infection. These viral mechanisms of immune regulation to IFN allow the virus to establish acute infections more efficiently, by partially counteracting IFN-β innate immune response in trigeminal ganglia favoring viral latency establishment.

Existen eventos desconocidos o pobremente comprendidos en las interacciones Leishmaniacélula hospedera que ameritan estudios en nuevos modelos in vitro. El propósito del presente trabajo fue evaluar, teniendo en cuenta variables de temperatura, concentración de C02 y cambios morfométricos de las células, la interacción de Leishmania chagasi con una línea celular (Lulo), previamente establecida, derivada de tejidos embrionarios de Lutzomyia longipalpis. La línea celular J774 se utilizó como control positivo de la infección. La cepa MH/CO/84/CI-044B de L. chagasi se usó para los ensayos de infección. Los parásitos se adicionaron a las células adheridas, tanto de Lulo como de J774, en una proporción de 5:1. La incubación se efectuó a 28°C y 37°C, en ausencia ypresencia de CO2. Se realizó un estudio morfométrico de las células antes y después de la infección. Las características ultraestructurales, tanto del parásito como de las células, se analizaron por microscopía electrónica. El mayor porcentaje de infección en las células Lulo a 28°C se registró el día seis post-infección (26,8%), mientras que a 37°C, sin atmósfera de CO2, el máximo valor (30,4%) se obtuvo el día nueve. Los análisis morfométricos mostraron un aumento significativo en el tamaño de las células infectadas de Lulo a 28°C y de J774 a 37°C con y sin atmósfera de CO2 respectivamente. There are unknown or poorly understood events in the Leishmania-host cell interactions that merit studies in new in vitro models. The aim of the present work was to evaluate Leishmania chagasi interaction with a cell line (Lulo) previously established and derived from Lutzomyia longipalpis embryonic tissues, bearing different temperatures and CO 2 concentrations in mind and morphometric changes of the cells. The J774 cell line was used as positive control of the infection. The L. chagasi MH/CO/84/CL-044B strain was used for infection assays. The parasites were added to adherent cells, in Lulo as well as J774, in a 5:1 ratio. Incubation was at 28°C and 37°C, in the absence and presence of CO 2. A morphometric study of the cells was carried out before and after infection. Both parasite and cell ultrastructure characteristics were analyzed by electron microscope. The greatest percentage of infection in the Lulo cells at 28°C (26,8%) was registered on day six post infection, while at 37°C, in the absence of CO 2, the maximum value (30,4%) was obtained on day nine. The morphometric analyses showed a significant increase in the size of Lulo cells infected at 28°C and J774 cells at 37°C with and without CO 2, respectively.

La infección causada por el virus del dengue (DENV) se ha relacionado con el desarrollo de alteraciones neurológicas y comportamentales en humanos. Dicha asociacione se ha confirmado por el desarrollo de signos claros de alteración neurológica durante y después de la infección y por la presencia de proteínas y/o RNA viral en líquido cefaloraquídeo o en muestras de tejido nervioso obtenidas post morten. Esto sugiere que el virus puede invadir el Sistema Nervioso Central (SNC). Por la dificultad de reproducir los signos y síntomas del dengue en animales, nuestro grupo desarrolló un modelo in vivo de neuroinfección en el cual ratones neonatos se inocularon a nivel periférico con una cepa de virus adaptada a tejido nervioso (D4MB-6). Como resultado, se observó que la variante viral logró invadir el SNC e infectó algunas poblaciones celulares como neuronas, oligodendrocitos y células de la microglía. Estas últimas presentaron evidentes cambios morfológicos que sugerían activación. Adicionalmente se observó que en el tejido nervioso de animales infectados la infección indujo una exacerbada respuesta inmune y la excitotoxicidad por glutamato, espectos que en conjunto causaron la muerte neuronal y el daño en la arquitectura tisular. Sin embargo, la población celular del tejido nervioso que secreta estas moléculas no ha sido identificada aún. Experimentalmente se ha demostrado que en diferentes patologías -incluso virales- la principal fuente de citoquinas pro-inflamatorias, glutamato y otros agentes provienen de las células de la microglía infectadas y/o activadas. Todos los agentes producidos y liberados por estas células, pueden de manera conjunta o independiente ocasionar el daño y la muerte neuronal. Por lo tanto, en este trabajo se evaluó en un cultivo primario de células de la microglía de ratón lactante, su susceptibilidad a la infección con la variante adaptada -D4MB-6- o no a tejido nervioso y algunos aspectos relacionados con su activación. Como resultado se observó que las células microgliales presentaron una alta susceptibilidad a la infección y en los tiempos post-infección evaluados presentaron altas tasas de proliferación y supervivencia. Adicionalmente se observó que las células presentaron cambios morfológicos y produjeron algunas moléculas pro-inflamatorias y glutamato, que indujeron a las células a sostener en los tiempos evaluados un estado de activación que fue modulado y regulado por los fármacos VPA o MK-801. En conjunto estos resultados permitieron describir que la infección por DENV indujo la activación y producción de agentes pro-inflamatorios y glutamato por parte de las células de la microglía, por lo tanto, sugerimos que estas células son centrales en el desarrollo de la nueuroinfección y neuropatogenia causada por el DENV. Magíster en Ciencias Básicas Biomédicas Maestría

Dengue disease statistics is mainly based on consulting patients with febrile illness, but misdiagnosed and asymptomatic cases are important to measure dengue epidemiology in endemic areas. The main objective of this work was to determine the prevalence of IgM and IgG antibodies or NS1 antigen and viral RNA in a group of healthy volunteers from an isolated village in Colombian Chocó rain forest. It found 51.7% of virologically PCR confirmed asymptomatic cases, despite low IgM seroprevalence. It was confirmed that all four serotypes are in the circulation and in 17.2% of individuals it detected natural coinfections of two or three different serotypes simultaneously. This is the first report in Colombia evaluating viremia in asymptomatic volunteers. These findings pose a big concern about the transmission of dengue virus by asymptomatic individuals because they can spread the virus without taking appropriate control measures.

Se formulan recomendaciones de un grupo de consenso de expertos sobre los criterios para evaluar el desempeño diagnóstico (tamaño y selección de muestras para sensibilidad y especificidad analíticas, criterios para establecer límites de detección, criterios para establecer el estándar de oro para las serologías) que deberíanser tenidos en cuenta al evaluar y validar las pruebas diagnósticas para SARS CoV-2. Con el propósito de asegurar la calidad de las pruebas serológicas a utilizar en el país, se recomienda la participación en un programa de control de calidad externo, que garantice la idoneidad y desempeño en la realización de laspruebas diagnósticas serológicas y moleculares durante esta pandemia, ya que su uso tiene profundas implicaciones para las medidas de intervención clínicas individuales y de seguimiento y control en salud pública. A consensus working group formulates recommendations on the criteria to evaluate the diagnostic performance (size and criteria of selection of samples to determine sensitivity, analytical specificity, criteria for limit of detection, criteria for gold standard to evaluate serological assays) that should considered during the evaluation and validation/verification of diagnostic tests for SARS CoV-2 infection. A national external quality control program should be established to guarantee the suitability and performance of these diagnostic serological and molecular tests during this pandemic, that will have deep implications on clinical and public health decisions.

Background Pseudomonas aeruginosa Sequence Type 235 is a clone that possesses an extraordinary ability to acquire mobile genetic elements and has been associated with the spread of resistance genes, including genes that encode for carbapenemases. Here, we aim to characterize the genetic platforms involved in resistance dissemination in bla KPC-2 -positive P. aeruginosa ST235 in Colombia. Results In a prospective surveillance study of infections in adult patients attended in five ICUs in five distant cities in Colombia, 58 isolates of P. aeruginosa were recovered, of which, 27 (46.6%) were resistant to carbapenems. The molecular analysis showed that 6 (22.2%) and 4 (14.8%) isolates harboured the bla VIM and bla KPC-2 genes, respectively. The four bla KPC-2-positive isolates showed a similar PFGE pulsotype and belonged to ST235. Complete genome sequencing of a representative ST235 isolate shows a unique chromosomal contig of 7097.241 bp with eight different resistance genes identified and five transposons: a Tn6162-like with ant(2″)-Ia, two Tn402-like with ant(3″)-Ia and bla OXA-2 and two Tn4401b with bla KPC-2. All transposons were inserted into the genomic islands. Interestingly, the two Tn4401b copies harbouring bla KPC-2 were adjacently inserted into a new genomic island (PAGI-17) with traces of a replicative transposition process. This double insertion was probably driven by several structural changes within the chromosomal region containing PAGI-17 in the ST235 background. Conclusion This is the first report of a double Tn4401b chromosomal insertion in P. aeruginosa, just within a new genomic island (PAGI-17). This finding indicates once again the great genomic plasticity of this microorganism.

Introduction. The aim of the present study was to determine the effects of vitamins D and E on the proliferation, morphology, and differentiation of human dental pulp stem cells (hDPSCs). Methods. In this in vitro experimental study, hDPSCs were isolated, characterized, and treated with vitamins D and E, individually and in combination, utilizing different doses and treatment periods. Changes in morphology and cell proliferation were evaluated using light microscopy and the resazurin assay, respectively. Osteoblast differentiation was evaluated with alizarin red S staining and expression of RUNX2, Osterix, and Osteocalcin genes using real-time RT-PCR. Results. Compared with untreated cells, the number of cells significantly reduced following treatment with vitamin D (49%), vitamin E (35%), and vitamins D + E (61%) after 144 h. Compared with cell cultures treated with individual vitamins, cells treated with vitamins D + E demonstrated decreased cell confluence, with more extensive and flatter cytoplasm that initiated the formation of a significantly large number of calcified nodules after 7 days of treatment. After 14 days, treatment with vitamins D, E, and D + E increased the transcription of RUNX2, Osterix, and Osteocalcin genes. Conclusions. Vitamins D and E induced osteoblastic differentiation of hDPSCs, as evidenced by the decrease in cell proliferation, morphological changes, and the formation of calcified nodules, increasing the expression of differentiation genes. Concurrent treatment with vitamins D + E induces a synergistic effect in differentiation toward an osteoblastic lineage.

Dengue has been a significant public health problem in Colombia since the simultaneous circulation of the four dengue virus serotypes. The replicative fitness of dengue is a biological feature important for virus evolution and contributes to elucidating the behavior of virus populations and viral pathogenesis. However, it has not yet been studied in Colombian isolates. This study aimed to compare the replicative fitness of the four dengue virus serotypes and understand the association between the serotypes, their in vitro infection ability, and their replication in target cells. We used three isolates of each DENV serotype to infect Huh-7 cells at an MOI of 0.5. The percentage of infected cells was evaluated by flow cytometry, cell viability was evaluated by MTT assay, and the pathogenicity index was calculated as a ratio of both parameters. The replicative fitness was measured by the number of viral genome copies produced using quantitative PCR and the production of infectious viral progeny was measured by plaque assay. We showed that Huh-7 cells were susceptible to infection with all the different strain isolates. Nevertheless, the biological characteristics, such as infectious ability and cell viability, were strain-dependent. We also found different degrees of pathogenicity between strains of the four serotypes, representative of the heterogeneity displayed in the circulating population. When we analyzed the replicative fitness using the mean values obtained from RT-qPCR and plaque assay for the different strains, we found serotype-dependent behavior. The highest mean values of replicative fitness were obtained for DENV-1 (log 4.9 PFU/ml) and DENV-4 (log 5.28 PFU/ml), followed by DENV-2 (log 3.9 PFU/ml) and DENV-3 (log 4.31 PFU/ml). The internal heterogeneity of the replicative fitness within each serotype could explain the simultaneous circulation of the four DENV serotypes in Colombia.

Endothelial activation and alteration during dengue virus (DENV) infection are multifactorial events; however, the role of extracellular vesicles (EVs) in these phenomena is not known. In the present study, we characterized the EVs released by DENV-2 infected U937 macrophage cell line and evaluated the changes in the physiology and integrity of the EA.hy926 endothelial cells exposed to them. U937 macrophages were infected, supernatants were collected, and EVs were purified and characterized. Then, polarized endothelial EA.hy926 cells were exposed to the EVs for 24 h, and the transendothelial electrical resistance (TEER), monolayer permeability, and the expression of tight junction and adhesion proteins and cytokines were evaluated. The isolated EVs from infected macrophages corresponded to exosomes and apoptotic bodies, which contained the viral NS3 protein and different miRs, among other products. Exposure of EA.hy926 cells to EVs induced an increase in TEER, as well as changes in the expression of VE-cadherin and ICAM in addition leads to an increase in TNF-α, IP-10, IL-10, RANTES, and MCP-1 secretion. These results suggest that the EVs of infected macrophages transport proteins and miR that induce early changes in the physiology of the endothelium, leading to its activation and eliciting a defense program against damage during first stages of the disease, even in the absence of the virus.

Background Folate is a naturally occurring, water-soluble B vitamin. The synthetic form of this compound is folic acid (FA), the deficiency of which is linked to neural tube disorders (NTD), which can be prevented by consuming it before, or during the early months of, pregnancy. However, the effect of FA on oral cleft formation remains controversial. The aim of the present study was to review the evidence concerning the effect of FA on the formation of cleft lip and palate (CLP) in both animals and humans, as well as its impact on different cell types. A search was conducted on various databases, including MEDLINE, EMBASE, and Central, for articles published until January 2020. Main body Current systematic reviews indicate that FA, alone or in combination with other vitamins, prevents NTD; however, there is no consensus on whether its consumption can prevent CLP formation. Conversely, the protective effect of FA on palatal cleft (CP) induction has been inferred from animal models; additionally, in vitro studies enumerate a cell-type and dose-dependent effect of FA on cell viability, proliferation, and differentiation, hence bolstering evidence from epidemiological studies. Conclusions Meta-analysis, animal models, and in vitro studies demonstrated the protective effect of FA against isolated CP; however, the heterogeneity of treatment protocols, doses, and FA administration method, as well as the different cell types used in in vitro studies, does not conclusively establish whether FA prevents CLP formation.

Objectives: Colombia is a dengue hyperendemic country; however, the prevalence of antibodies against dengue in the general population including the inhabitants of rural areas is unknown. This study aimed to determine the prevalence of dengue IgM and IgG antibodies in healthy children and adults in urban and rural areas of seven different endemic regions in Colombia between 2013 and 2015. Design or method: Blood samples from healthy volunteers (1,318) were processed by serology (by indirect IgG and capture IgM and IgG ELISA) and molecular tests to detect viral RNA and circulating serotypes. Results: The seroprevalence of IgG for dengue were 85% in children and over 90% for adults. In addition to the high IgM positive rate (14.9%) and secondary recent infection marker rate (capture IgG, 16%), 8.4% of the healthy volunteers were positive for dengue virus (DENV) RNA. Conclusion: This study confirmed the broad and permanent circulation of DENV in Colombia and the high rates of infection and reinfection suffered by its inhabitants. This information can be used by the health authorities to strengthen vector control and vaccine policies and review the algorithms of diagnosis and disease management in children and adults. Keywords: Seroprevalence, Dengue symptomatic, Dengue asymptomatic, Colombia

La Asociación Colombiana de Infectología (ACIN) y el Instituto de Evaluación de Nuevas Tecnologías de la Salud (IETS) conformó un grupo de trabajo para desarrollar recomendaciones informadas y basadas en evidencia, por consenso de expertos para la atención, diagnóstico y manejo de casos de Covid 19. Estas guías son dirigidas al personal de salud y buscar dar recomendaciones en los ámbitos de la atención en salud de los casos de Covid-19, en el contexto nacional de Colombia.

RESUMEN Actualmente, la infección por el virus de dengue (DENV) es uno de los problemas más importantes de salud pública en países tropicales y endémicos como Colombia, pues en tanto puede ser producida por cuatro diferentes serotipos virales, durante las infecciones secundarias se presentan frecuentemente cuadros más severos que incluso pueden llevar a desenlaces fatales. El centro de la fisiopatología del dengue grave es el daño producido al endotelio, que se traduce en un aumento en la permeabilidad vascular que se evidencia como fuga plasmática, descontrol en la coagulación y daño de órganos. Aunque hay varias teorías que explican la enfermedad severa, el fenómeno denominado amplificación de la infección dependiente de anticuerpos (antibody dependent enhancement, ADE) es el más conocido. En este, se postula que el virus causante de una infección secundaria es reconocido, pero no neutralizado, por anticuerpos generados en la infección previa e internalizado en las células susceptibles usando receptores Fc-gamma, lo cual aumenta la replicación viral e induce modificaciones en la respuesta inmune celular que contribuyen al desarrollo de dengue grave. En este escrito, se realiza una revisión de los hallazgos sobre los mecanismos involucrados en el fenómeno de ADE y cómo pueden contribuir a la progresión hacia dengue grave, describiendo los conceptos de ADE extrínseco e intrínseco, además de como este fenómeno debe ser tenido en cuenta para el diseño, desarrollo e implementación de una vacuna para dengue, en tanto es capaz de afectar su eficacia y seguridad. ABSTRACT Dengue virus infection is the most important vector transmitted disease in tropical countries such as Colombia, where all the four dengue virus serotypes are circulating and are involved in successive secondary infections which induce severe or even fatal cases. The central key to understanding the severe dengue cases is the endothelial function damage which appears as plasma leakage, coagulation impairment, and organ compromise. Severe dengue could be explained by different theories, among them the antibody-dependent enhancement (ADE) phenomenon is the best known. This theory postulates that the second heterotypic virus causing a secondary infection is recognized by antibodies raised during the first infection but are ineffective to neutralize the virus. Instead this virus-antibody complex is internalized by Fc-gamma receptor-bearing cells increasing the viral replication and inducing an aberrant immune response that contributes to severe dengue presentation. This manuscript is aimed to review the evidence about the ADE phenomenon and its involvement in the severe evolution of dengue cases. Here, it will be described the extrinsic and intrinsic ADE concepts and how these phenomena must be considered to the design, development, and implementation of a dengue vaccine because the evidence indicates that ADE affects both efficacy and safety of vaccine prototypes.

Estudios in vitro de la patogénesis del citomegalovirus humano (HCMV) se hace empleando cepas adaptadas de laboratorio que han perdido algunas de sus características durante ese proceso. En vista que el HCMV se excreta en distintos fluidos corporales, dependiendo de la condición clínica del paciente, en este trabajo se propuso aislar y propagar HCMV en fibroblastos MRC-5 usando muestras de orina, lavado broncoalveolar, saliva y plasma de pacientes pediátricos. Estas muestras fueron inoculadas sobre los cultivos celulares por 14 días o hasta alcanzar un efecto citopático en el 80 % de la monocapa. El lisado celular y el sobrenadante del aislamiento se usaron para hacer pasajes virales sucesivos. Además de HCMV, el virus de herpes simple se aisló en todas las muestras de saliva. Con el empleo de los sueros positivos para HCMV se observó la formación de agregados y daño inmediato en la monocapa que impidieron su uso. Una muestra de lavado broncoalveolar indujo ECP desde la inoculación, similar al control positivo para HCMV (cepas Towne y Merlin), por lo que fue propagada y se tituló. Un segundo aislamiento viral obtenido de la orina de un paciente con infección congénita no produjo ECP a pesar de ser confirmado por PCR. En los aislamientos llevados hasta el pasaje 1, se descartó la presencia de enterovirus y adenovirus. A pesar de la evidente dificultad para aislar y propagar el HCMV, fue posible obtener un aislamiento usando un protocolo de Shell vial e inoculación modificado, y con un seguimiento prolongado del proceso. In vitro studies on the pathogenesis of the human cytomegalovirus (HCMV) are conducted regularly using laboratory adapted strains that lose some characteristics during the adaptation process. Since HCMV is excreted from bodily fluids during infection or reactivation, this work aimed to isolate and culture HCMV from the MRC-5 human cells found in the urine, bronchoalveolar lavage, saliva, and plasma samples of pediatric patients with probable or confirmed infection. The samples were inoculated on cell cultures either for 14 days or until a cytopathic effect (CPE) of 80 % was observed. The cell lysates and supernatants were used to perform successive viral passages. Besides HCMV, the herpes simplex virus was detected from all the saliva samples. Inoculation of the HCMV positive sera induced cell clustering and immediate monolayer damage that restricted their use. One sample of bronchoalveolar lavage induced a CPE after inoculation like that of the HCMV reference strains (Towne and Merlin), which was consequently propagated and titrated. A second viral isolate derived from the urine sample of a patient with congenital infection did not demonstrate a CPE, although presence of the virus had been confirmed using PCR. The viral isolates were examined and found to be negative for adenoviruses or enteroviruses. Despite the evident difficulty encountered for the isolation and harvesting of the HCMV, this work shows that it was possible to obtain a low passage viral strain using a modified shell vial method and inoculation protocol with extended follow-up and confirmation.

Background: YlbF and YmcA are two essential proteins for the formation of biofilm, sporulation, and competence in Bacillus subtilis. In these two proteins, a new protein domain called com_ylbF was recently discovered, but its role and protein function has not yet been established. Objective: In this study, we identified and performed an “in silico” structural analysis of the YheA protein, another com_ylbF-containing protein, in the opportunistic pathogen Staphylococcus aureus. Methods: The search of the yheA gene was performed using BLAST-P and tBLASn algorithms. The three-dimensional (3D) models of YheA, as well as YlbF and YmcA proteins, were built using the I-TASSER and Quark programs. The identification of the native YheA in Staphylococcus aureus was carried out through chromatography using the FPLC system. Results: We found that YheA protein is more widely distributed in Gram-positive bacteria than YlbF and YmcA. Two new and important characteristics for YheA and other com_ylbF-containing proteins were found: a highly conserved 3D structure and the presence of a putative conserved motif located in the central region of the domain, which could be involved in its function. Additionally, we established that Staphylococcus aureus expresses YheA protein in both planktonic growth and biofilm. Finally, we suggest renaming YheA as glutamine-rich protein (Qrp) in S. aureus. Conclusion: The Grp (YheA), YlbF, and YmcA proteins adopt a highly conserved three-dimensional structure, harboring a protein-specific putative motif within the com_ylbF domain, which possibly favors the interaction with their substrates. Finally, Staphylococcus aureus expresses the Grp (YheA) protein in both planktonic and biofilm growth.

Es bien sabido que los adhesivos hidrofílicos actuales producen una capa híbrida que es inestable con el tiempo, en parte por la activación de las metaloproteinasas de la matriz extracelular (MMP) que degradan la red de colágeno expuesta por el acondicionamiento ácido y se infiltran parcialmente por los monómeros de resina. El objetivo de este estudio es evaluar el efecto de la aplicación de un flavonoide experimental (MRT-1) en la interfase adhesiva dentina-resina, en términos de actividad de MMP y resistencia de unión microtensil (μTBS). el ensayo de actividad MMP se realizó en bloques de dentina, que se obtuvieron de terceros molares bajo consentimiento informado. Todas las muestras se desmineralizaron con ácido fosfórico al 10% overnight y se distribuyeron aleatoriamente en los grupos de prueba. La actividad de MMP se midió con un kit genérico de ensayo de actividad MMP. Para la prueba μTBS, se eliminó el esmalte oclusal de 20 terceros molares repartidos aleatoriamente en 4 grupos de prueba (MRT-1 a 600 μM, etanol al 100%, clorhexidina al 0.2% y control negativo, para el protocolo adhesivo grabado-enjuague). En cada grupo se aplicó el tratamiento adhesivo propuesto y se construyeron bloques de resina que, posteriormente, se seccionaron en barras de 1,0 mm2 para hacer la prueba tensil inmediata y después de 6 meses de almacenamiento en saliva artificial. el ensayo de actividad de MMP mostró que MRT-1 al 600 μM (120s) fue eficaz para disminuir la actividad de MMP en un 74% con respecto al grupo control. En la prueba μTBS, MRT-1 al 600 μM, clorhexidina al 0.2% y etanol al 100%, aplicados de manera independiente después del grabado ácido de la dentina, no interfirieron con la adhesión. MRT-1 al igual que la clorhexidina mantuvo los mismos valores de resistencia de unión durante 6 meses, mientras que el control negativo disminuyó los valores de μTBS después del envejecimiento. el tratamiento con MRT-1, clorhexidina y etanol estabilizó la interfase dentina-resina durante 6 meses. El uso de un flavonoide experimental (MRT-1) durante 2 min sería útil en un protocolo clínico de adhesión para preservar la interfase dentina-resina. Magíster en Ciencias Odontológicas Maestría It is well-known that conventional hydrophilic adhesives produce a hybrid layer that is unstable over time, in part because of the activation of extracellular matrix metalloproteinases (MMPs) that degrade the collagen network exposed by acid conditioning. In addition, the network can be partially infiltrated by resin monomers. The aim of this study is to evaluate the effects of the application of an experimental flavonoid (MRT-1) on the dentin-resin adhesive interface in terms of MMP activity and microtensile bond strength (μTBS). An MMP activity assay was performed on dentin beams obtained from third molars with informed consent. The specimens were demineralized with 10% phosphoric acid overnight and randomly divided into test groups. The MMP activity was measured with a generic MMP activity assay kit. For the μTBS test, occlusal enamel was removed from 20 third molars and divided randomly into 4 test groups (600 μM MRT-1, 100% ethanol, 0.2% chlorhexidine, and negative control groups for etch-rinse adhesive protocol). Each group was subjected to the proposed adhesive treatment, and composite buildups were constructed and sectioned in sticks of 1.0 mm2 for immediate tension tests and after 6 months of storage in artificial saliva. The MMP activity assay showed that 600 μM MRT-1 (120 s) effectively decreased the MMP activity by 74% compared to the control group. In the μTBS test, 600 μM MRT-1, 2% chlorhexidine and 100% ethanol applied after acid etching did not interfere with the μTBS of the dentin. MRT-1, similar to chlorhexidine, maintained the same bond strength values over 6 months, while the negative control showed decreased μTBS values after aging. MRT-1, chlorhexidine, and ethanol treatments stabilized the dentin-resin interface over 6 months. Application of the experimental flavonoid MRT-1 for 2 min would be useful in a dentin-bonding clinical protocol to preserve the dentin-resin interface.

More than 500 million people worldwide are infected each year by any of the four-dengue virus (DENV) serotypes. The clinical spectrum caused during these infections is wide and some patients may develop neurological alterations during or after the infection, which could be explained by the cryptic neurotropic and neurovirulent features of flaviviruses like DENV. Using in vivo and in vitro models, researchers have demonstrated that DENV can affect the cells from the blood–brain barrier (BBB) in several ways, which could result in brain tissue damage, neuronal loss, glial activation, tissue inflammation and hemorrhages. The latter suggests that BBB may be compromised during infection; however, it is not clear whether the damage is due to the infection per se or to the local and/or systemic inflammatory response established or activated by the BBB cells. Similarly, the kinetics and cascade of events that trigger tissue damage, and the cells that initiate it, are unknown. This review presents evidence of the BBB cell infection with DENV and the response established toward it by these cells; it also describes the consequences of this response on the nervous tissue, compares these evidence with the one reported with neurotropic viruses of the Flaviviridae family, and shows the complexity and unpredictability of dengue and the neurological alterations induced by it. Clinical evidence and in vitro and in vivo models suggest that this virus uses the bloodstream to enter nerve tissue where it infects the different cells of the neurovascular unit. Each of the cell populations respond individually and collectively and control infection and inflammation, in other cases this response exacerbates the damage leaving irreversible sequelae or causing death. This information will allow us to understand more about the complex disease known as dengue, and its impact on a specialized and delicate tissue like is the nervous tissue.

Fluorotic teeth could either be more resistant or more susceptible to the caries process than sound ones due to their higher enamel fluoride concentration and higher porosity (subsurface hypomineralization), respectively; however, there is no consensus on this subject. In this study, a total of 49 human unerupted third molars presenting Thylstrup and Fejerskov (TF) fluorosis scores 0-4 were used. Two enamel slabs were obtained from each tooth. The rest of the tooth crown was powdered, and the enamel was separated from the dentine. In purified powdered enamel, the calcium (Ca), inorganic phosphate (Pi), and fluoride (F) concentrations were determined. The F concentration gradient throughout the enamel and in the enamel volume was determined in one slab. The other enamel slab was isolated with acid-resistant varnish, subjecting the exposed enamel surface half to a pH-cycling model to evaluate its demineralization resistance and to calculate the demineralization area. The nonexposed surface was used to determine the natural hypomineralization area found in fluorotic enamel and normalize the demineralization data. The hypomineralization and demineralization areas were assessed by cross-sectional microhardness. For statistical analyses, the data for TF1 and 2, and for TF3 and 4 were pooled. Concentrations of powered enamel Ca and Pi were not significantly different (p > 0.05) among groups TF0, TF1-2 and TF3-4, but a higher F concentration was found in fluorotic enamel (p < 0.05). Highly fluorotic teeth (TF3-4) presented a greater hypomineralization subsurface area and demonstrated lower demineralization resistance than sound enamel (p < 0.05). The findings suggest that a higher severity of fluorosis makes enamel less resistant to the caries process due to its greater subsurface mineral area exposed to demineralization and deeper acid diffusion through the enamel.

Introduction: Respiratory syncytial virus (RSV) is the most common cause of acute respiratory infections in children younger than two years but also produces infection in older children and even reinfection in people of any age, a characteristic related to the existence of different infecting subtypes and genotypes. Although Colombia has established the surveillance of classical respiratory viruses, there is no information about the RSV genotypes circulating in Colombian patients. Methodology: A subgroup of 227 previously RSV positive respiratory secretion samples were taken from a nationwide surveillance study, amplified and sequenced to define the circulation pattern of RSV subtypes and genotypes during 2000-2009 period in Colombia. Results. RSV exhibited seasonal behavior with an A subtype more prevalent. Both RSV subtypes had low nucleotide variability. During the study period, the GA2 and GA5 genotypes from RSV subtype A and the BA genotype from RSV subtype B were found. Conclusion. In this report, for the first time RSV genotypes circulating in Colombia were described, this information adds valuable information about virus epidemiology helping to understand the RSV epidemic and prepare our country for the introduction of new vaccines.

Odontoblasts, the main cell type in teeth pulp tissue, are not cultivable and they are responsible for the first line of response after dental restauration. Studies on dental materials cytotoxicity and odontoblast cells physiology require large quantity of homogenous cells retaining most of the phenotype characteristics. Odontoblast-like cells (OLC) were differentiated from human dental pulp stem cells using differentiation medium (containing TGF-β1), and OLC expanded after trypsinization (EXP-21) were evaluated and compared. Despite a slower cell growth curve, EXP-21 cells express similarly the odontoblast markers dentinal sialophosphoprotein and dentin matrix protein-1 concomitantly with RUNX2 transcripts and low alkaline phosphatase activity as expected. Both OLC and EXP-21 cells showed similar mineral deposition activity evidenced by alizarin red and von Kossa staining. These results pointed out minor changes in phenotype of subcultured EXP-21 regarding the primarily differentiated OLC, making the subcultivation of these cells a useful strategy to obtain odontoblasts for biocompatibility or cell physiology studies in dentistry.

Introducción. La replicación del virus del dengue se ha considerado principalmente citoplásmica; sin embargo, en diversos estudios se ha informado que algunos flavivirus pueden utilizar factores intranucleares como parte de la maquinaria que utilizan para aumentar la capacidad de infección en la célula huésped. En este trabajo se describen las alteraciones a nivel nuclear en células infectadas con dengue, probablemente involucradas en procesos de replicación viral. Objetivo. Presentar las observaciones ultraestructurales de células C6/36 de Aedes albopictus infectadas con el virus del dengue de tipo 2. Materiales y métodos. Se infectaron células C6/36 con suero de un paciente con diagnóstico de dengue 2; posteriormente, se mantuvieron en medio de cultivo durante 10 días y se evaluó el efecto citopático. Las células se procesaron para los ensayos de inmunofluorescencia y microscopía electrónica de transmisión, con el fin de hacer el estudio ultraestructural. Resultados. Los ensayos de inmunofluorescencia confirmaron la presencia de la proteína E viral asociada con sincitios celulares en el cultivo. En el estudio ultraestructural, las células infectadas tenían estructuras vesiculares y tubulares, y cisternas dilatadas del retículo endoplásmico en el citoplasma. Las partículas virales se encontraron exclusivamente en vacuolas localizadas en el citoplasma. Los núcleos de los sincitios celulares contenían estructuras de membrana dispuestas en forma circular y, en algunos casos, dichos sincitios presentaban lisis. En ningún caso se observaron partículas virales en el núcleo. Conclusiones. No se habían reportado alteraciones ultraestructurales en los núcleos de células infectadas con el virus del dengue detectadas mediante técnicas de microscopia electrónica. Es probable que tales modificaciones estén asociadas con procesos intranucleares de replicación como un mecanismo alternativo. Introduction: Dengue virus replication has been considered mainly cytoplasmic, however, studies indicate that some flaviviruses may use the intranuclear pathway as part of the machinery that the virus uses to increase infection capacity in the host cell. This paper describes alterations at nuclear level in the cell infected with dengue, which are likely involved in the virus replication processes. Objective: This paper addresses the ultrastructural observations of C6/36 cells of the Aedes albopictus mosquito infected with dengue virus type 2. Materials and methods: C6/36 cells were infected in culture medium with the serum of a patient positively diagnosed for dengue 2. Subsequently, the cells were incubated for 10 days and the cytopathic effect was assessed. The cells were processed for immunofluorescence assays and transmission electron microscopy. Results: The immunofluorescence assays confirmed the presence of viral protein E associated with cellular syncytia in the culture. In the ultrastructural study, the infected cells showed vesicular-tubular structures and dilated cisterns of the endoplasmic reticulum at the cytoplasmic level. Viral particles were found exclusively in cytoplasm localized within the vacuoles. Nuclei of cellular syncytia showed membrane structures arranged in a circular shape and, in some cases, these syncytia displayed lysis; in no case viral particles were observed at the nuclear level. Conclusions: The ultrastructural alterations of nuclei in cells infected with the dengue virus using electron microscopy techniques had not been reported before, as far as we know. It is likely that such modifications are associated with replicative processes at an intranuclear level as an alternate replication mechanism.

© The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. Bacteria that produce the broad-spectrum Carbapenem antibiotic NewDelhi Metallo-b-lactamase (NDM) place a burden on health care systems worldwide, due to the limited treatment options for infections caused by them and the rapid global spread of this antibiotic resistancemechanism.Although it is believed that theassociated resistancegenebla NDM-1 originated inAcinetobacter spp., the role of Enterobacteriaceae in its dissemination remains unclear. In this study, we usedwhole genome sequencing to investigate the dissemination dynamics of blaNDM-1-positive plasmids in a set of 21 clinical NDM-1-positive isolates from Colombia and Mexico (Providencia rettgeri, Klebsiella pneumoniae, and Acinetobacter baumannii) aswell as six representative NDM-1-positive Escherichia coli transconjugants. Additionally, the plasmids from three representative P. rettgeri isolates were sequenced by PacBio sequencing and finished. Our results demonstrate the presence of previously reported plasmids from K. pneumoniae and A. baumannii in different genetic backgrounds and geographically distant locations in Colombia. Three new previously unclassified plasmids were also identified in P. rettgeri from Colombia and Mexico, plus an interesting genetic link between NDM-1-positive P. rettgeri from distant geographic locations (Canada, Mexico, Colombia, and Israel) without any reported epidemiological links was discovered. Finally, we detected a relationship between plasmids present in P. rettgeri and plasmids from A. baumannii and K. pneumoniae. Overall, our findings suggest a Russian dollmodel for the dissemination of blaNDM-1 in LatinAmerica,with P. rettgeri playing a central role in this process, andrevealnewinsights into the evolution and disseminationof plasmids carrying such antibiotic resistance genes.

Dengue virus (DENV) is an arbovirus of the Flaviviridae family and is an enveloped virion containing a positive sense single-stranded RNA genome. DENV causes dengue fever (DF) which is characterized by an undifferentiated syndrome accompanied by fever, fatigue, dizziness, muscle aches, and in severe cases, patients can deteriorate and develop life-threatening vascular leakage, bleeding, and multi-organ failure. DF is the most prevalent mosquito-borne disease affecting more than 390 million people per year with a mortality rate close to 1% in the general population but especially high among children. There is no specific treatment and there is only one licensed vaccine with restricted application. Clinical and experimental evidence advocate the role of the humoral and T-cell responses in protection against DF, as well as a role in the disease pathogenesis. A lot of pro-inflammatory factors induced during the infectious process are involved in increased severity in dengue disease. The advances in DF research have been hampered by the lack of an animal model that recreates all the characteristics of this disease. Experiments in nonhuman primates (NHP) had failed to reproduce all clinical signs of DF disease and during the past decade, humanized mouse models have demonstrated several benefits in the study of viral diseases affecting humans. In DENV studies, some of these models recapitulate specific signs of disease that are useful to test drugs or vaccine candidates. However, there is still a need for a more complete model mimicking the full spectrum of DENV. This review focuses on describing the advances in this area of research.

There is controversy with regard to the entry pathway of the rabies virus (RABV) into the central nervous system (CNS). Some authors have suggested that the virus inoculated at the periphery is captured and transported to CNS only by motor neurons; however, it has been reported that dorsal root ganglia (DRG) sensory neurons capture and transport the virus to the spinal cord (SC) and then to the brain. It is probable that preferences for one pathway or another depend on the site of inoculation and the post-infection time. Therefore, in the present study, we evaluated different vertebral segments and post-infection times, along with the location, number, and subpopulation of sensory neurons susceptible to infection after inoculating RABV in the footpads of adult mice. It was noted that the virus inoculated in the footpad preferentially entered the CNS through the large-sized DRG sensory neurons, while infection of the motor neurons occurred later. Further, it was found that the virus was dispersed in spinal cord trans-synaptically through the interneurons, arriving at both sensory neurons and contralateral motor neurons. In conclusion, we observed that RABV inoculated in the plantar footpad is captured preferentially by large sensory neurons and is transported to the DRG, where it replicates and is spread to the SC using transynaptic jumps, infecting sensory and motor neurons at the same level before ascending to the brain.

Introducción. La incidencia y la prevalencia del dengue en Cundinamarca son elevadas y, recientemente, se detectó Aedes aegypti en algunas áreas rurales del departamento. Objetivo. Evaluar la transmisión transovárica del virus del dengue en larvas y pupas recolectadas en áreas rurales del municipio de Anapoima. Materiales y métodos. Se recolectaron ejemplares vivos en 53 viviendas y se transportaron al laboratorio de Anapoima, donde se clasificaron, se agruparon y se congelaron. Llevadas a Bogotá, se las homogeneizó, se les extrajo el ARN con Trizol®, se las sometió a una reacción en cadena de la polimerasa de transcripción inversa (Reverse Transcription Polymerase Change Reaction, RT-PCR) y a PCR convencional, y los productos amplificados se analizaron en geles de agarosa al 2 %. Resultados. En 54,7 % de las viviendas evaluadas se encontraron formas inmaduras del vector y el serotipo más frecuente fue el DENV-1. Sin embargo, en algunos pools se detectó la presencia simultánea de los serotipos DENV 1 y 2, DENV 1 y 3, y DENV 1 y 4, así como los serotipos DENV 1, 2 y 3. Conclusión. Los resultados confirmaron la transmisión vertical del virus de manera natural en el área rural del municipio, lo cual reafirma la capacidad vectorial de A. aegypti y explica, en parte, la persistencia del virus en la región y la posibilidad de que en la fase adulta el vector lo transmita sin haber consumido sangre infectada. Esta situación aumenta el riesgo de infección por el virus del dengue en Colombia y, por lo tanto, la necesidad de adelantar programas de prevención y control en todas las zonas con presencia del mosquito. Introduction: There is a high incidence and prevalence of dengue in the department of Cundinamarca, and recently Aedes aegypti, the main vector of dengue virus (DENV), was detected in some of its rural areas. Objective: To evaluate viral transovarial transmission in larvae and pupae collected in rural areas of the municipality of Anapoima, Cundinamarca. Materials and methods: Live larvae and pupae were collected from 53 homes and later they were taken to the laboratory in Anapoima, where they were classified, pooled and frozen. In Bogotá, they were homogenized, RNA was extracted with TrizolTM, and RT-PCR and conventional PCR were performed. The amplified products were analyzed on 2% agarose gels. Results: In 54.7% of the houses we found A. aegypti in immature stages, and DENV-1 was the most frequent serotype. However, the simultaneous presence of DENV 1 and 2, DENV 1 and 3, DENV 1 and 4, and DENV 1, 2 and 3 serotypes was detected in some pools. Conclusion: The results confirmed the natural vertical transmission of the virus in the rural area under study. These findings confirmed the vector capacity of A. aegypti, and partly explains the persistence of the virus in the region and the possibility of transmission by the vector during adulthood without having ingested infected blood. This situation increases the risk of DENV infection in Colombia and the need for prevention and control programs in all areas where the mosquito is present.

9 p., Background: Dengue is one of the most important vector-borne diseases in the world, causing significant morbidity and economic impact. In Colombia, dengue is a major public health problem. Departments of La Guajira, Cesar and Magdalena are dengue endemic areas. The objective of this research is to determine the seroprevalence and the incidence of dengue virus infection in the participating municipalities from these Departments, and also establish the association between individual and housing factors and vector indices with seroprevalence and incidence. We will also assess knowledge, attitudes and practices, and willingness-to-pay for dengue vaccine. Methods: A cohort study will be assembled with a clustered multistage sampling in 11 endemic municipalities. Approximately 1000 homes will be visited to enroll people older than one year who living in these areas, who will be followed for 1 year. Dengue virus infections will be evaluated using IgG indirect ELISA and IgM and IgG capture ELISA. Additionally, vector indices will be measured, and adult mosquitoes will be captured with aspirators. Ovitraps will be used for continuous estimation of vector density. Discussion: This research will generate necessary knowledge to design and implement strategies with a multidimensional approach that reduce dengue morbidity and mortality in La Guajira and other departments from Colombian Caribbean.

Infection with dengue virus presents a broad clinical spectrum, which can range from asymptomatic cases to severe cases that are characterised by haemorrhagic syndrome and/or shock. The reason for such variability remains unknown. This work evaluated thein vitropermissiveness of mouse, rat, hamster and guinea pig macrophages to infection by dengue virus 2 (DENV2). The results established that macrophages derived from the BALB/c mouse strain showed higher permissiveness to DENV2 infection than macrophages from other rodent species, although all rodent species studied had the C820T mutation in the oligoadenylate synthetase 1b gene, indicating no relationship to the differentin vitrosusceptibilities of mouse cells at this locus. Other molecular mechanisms related to flavivirus susceptibility remain to be explored.

The high levels of dengue-virus (DENV) seroprevalence in areas where the Zika virus (ZIKV) is circulating and the cross-reactivity between these two viruses have raised concerns on the risk of increased ZIKV disease severity for patients with a history of previous DENV infections. To determine the role of DENV preimmunity in ZIKV infection, we analyzed the T- and B-cell responses against ZIKV in donors with or without previous DENV infection. Using peripheral blood mononuclear cells (PBMCs) from donors living in an endemic area in Colombia, we have identified, by interferon (IFN)-&gamma, enzyme-linked immunospot (ELISPOT) assay, most of the immunodominant ZIKV T-cell epitopes in the nonstructural (NS) proteins NS1, NS3, and NS5. Analyses of the T- and B-cell responses in the same donors revealed a stronger T-cell response against peptides conserved between DENV and ZIKV, with a higher level of ZIKV-neutralizing antibodies in DENV-immune donors in comparison with DENV-na&iuml, ve donors. Strikingly, the potential for antibody-mediated enhancement of ZIKV infection was reduced in donors with sequential DENV and ZIKV infection in comparison with donors with DENV infection only. Altogether, these data suggest that individuals with DENV immunity present improved immune responses against ZIKV.

Rabies virus P protein participates as a regulating factor in viral transcription and replication; recent studies found an antitranscriptional and antireplicative effect of nerve growth factor (NGF) and Neurotrophin-3 (NT-3) in infected neuron cultures. We investigated here the specific effect of the neurotrophins on P protein, evaluating its synthesis and subcellular distribution in adult mouse dorsal root ganglia neuron cultures infected and treated with NGF or NT-3. The results showed that NGF, but not NT-3, caused an increase in the quantity of P protein and an accumulation of protein in neuronal bodies, revealing changes in transport to the neuritic processes.

Introducción. El trasplante de precursores hematopoyéticos es una alternativa en el tratamiento de diversas condiciones en la población pediátrica. La intensidad del acondicionamiento para el trasplante predispone al desarrollo de complicaciones en los receptores. Las infecciones por el virus herpes simple 1 (HSV-1), el virus herpes simple 2 (HSV-2), el citomegalovirus (CMV) humano y el virus de Epstein-Barr (EBV) son una causa importante de morbimortalidad en estos pacientes. La reactivación de infecciones latentes puede producir descargas virales asintomáticas detectables en la saliva, lo cual ayuda a determinar el comportamiento de dichas infecciones en pacientes con trasplante y a establecer el diagnóstico temprano de la reactivación. Objetivo. Evaluar el comportamiento de la descarga viral de HSV-1, HSV-2, CMV y EBV en la saliva de pacientes hospitalizados en la Unidad de Trasplante de la Fundación HOMI - Hospital de la Misericordia, entre enero y noviembre de 2012. Materiales y métodos. Se evaluaron muestras de saliva de 17 receptores de trasplante. La presencia de ADN de HSV-1, HSV-2, CMV y EBV en las muestras de saliva se detectó mediante reacción en cadena de la polimerasa convencional. Resultados. Se detectó el ADN del HSV-2 en la saliva de cuatro pacientes, del CMV en la de cuatro y del EBV en la de nueve, lo cual se asoció con leucopenia. Cuatro de los 17 pacientes presentaron cargas simultáneas de CMV y EBV. No se detectó el ADN del HSV-1. Conclusiones: Se demostró una descarga asintomática de HSV-2, CMV y EBV asociada a leucopenia en la saliva de los pacientes. Introduction: Hematopoietic stem cell transplantation in pediatric patients is an alternative treatment for different diseases. The conditioning regimen for transplant predisposes recipients to the development of infections. Viral infections by herpes simplex virus 1 (HSV-1), herpes simplex virus 2 (HSV-2), human cytomegalovirus (CMV), and Epstein-Barr virus (EBV), are the most common, and the leading cause of morbidity and mortality among these patients. These viruses lie dormant in various cell types and the reactivation of latent infections may lead to asymptomatic viral shedding in saliva. The detection of these viruses in secretions may contribute to understand the behavioral dynamics of these viral infections in transplanted patients, and to the early diagnosis of reactivation. Objective: To assess HSV-1, HSV-2, CMV and EBV viral shedding in the saliva of patients admitted for hematopoietic stem cell transplantation at Fundación HOMI - Hospital de la Misericordia between January and November of 2012. Materials and methods: We evaluated stimulated saliva samples of 17 hematopoietic stem cell transplantation recipients weekly. We performed DNA extraction from saliva, and we evaluated the presence of DNA for HSV-1, HSV-2, CMV, and EBV by PCR. Results: While we detected HSV-2 and CMV DNA in the saliva of four patients, EBV DNA was detected in nine patients with leukopenia. In contrast, we did not detect HSV-1 DNA in saliva. Additionally, four out of the 17 patients showed a simultaneous shedding of CMV and EBV. Conclusions: By conventional PCR, we demonstrated asymptomatic HSV-2, CMV, and EBV viral shedding in saliva, associated with leukopenia.

The Aedes aegypti vector for dengue virus (DENV) has been reported in urban and periurban areas. The information about DENV circulation in mosquitoes in Colombian rural areas is limited, so we aimed to evaluate the presence of DENV in Ae. aegypti females caught in rural locations of two Colombian municipalities, Anapoima and La Mesa. Mosquitoes from 497 rural households in 44 different rural settlements were collected. Pools of about 20 Ae. aegypti females were processed for DENV serotype detection. DENV in mosquitoes was detected in 74% of the analysed settlements with a pool positivity rate of 62%. The estimated individual mosquito infection rate was 4.12% and the minimum infection rate was 33.3/1,000 mosquitoes. All four serotypes were detected; the most frequent being DENV-2 (50%) and DENV-1 (35%). Two-three serotypes were detected simultaneously in separate pools. This is the first report on the co-occurrence of natural DENV infection of mosquitoes in Colombian rural areas. The findings are important for understanding dengue transmission and planning control strategies. A potential latent virus reservoir in rural areas could spill over to urban areas during population movements. Detecting DENV in wild-caught adult mosquitoes should be included in the development of dengue epidemic forecasting models.

Primary cultures were made from adult mouse spinal ganglia for depicting an ultrastructural description of rabies virus (RABV) infection in adult mouse sensory neuron cultures; they were infected with rabies virus for 24, 36, and 48 h. The monolayers were processed for transmission electron microscopy and immunochemistry studies at the end of each period. As previously reported, sensory neurons showed great susceptibility to infection by RABV; however, in none of the periods evaluated were assembled virions observed in the cytoplasm or seen to be associated with the cytoplasmic membrane. Instead, fibril matrices of aggregated ribonucleoprotein were detected in the cytoplasm. When infected culture lysate were inoculated into normal animals via intra-cerebral route it was observed that these animals developed clinical symptoms characteristic of infection and transmission electron microscopy revealed assembled virions in the cerebral cortex and other areas of the brain. Sensory neurons infected in vitro by RABV produced a large amount of unassembled viral ribonucleoprotein. However, this intracellular material was able to produce infection and virions on being intra-cerebrally inoculated. It can thus be suggested that the lack of intracellular assembly in sensory neurons forms part of an efficient dissemination strategy.

This work was aimed at the morphological and biochemical characterisation of the most susceptible neuro- nal subpopulation to rabies virus (RABV) infection. Adult mouse DRG cultures were infected with RABV and dou- ble-processed for viral antigen detection and neuropeptides: calcitonine gene-related peptide (CGRP), galanin (GAL), substance P (SP), neuropeptide Y (NPY) and vasoactive intestinal peptide (VIP). It was found that 56% of the neu- rons in culture were small (diameter

Introducción. El diagnóstico adecuado de dengue por laboratorio es importante para la atención, así como para el control de brotes y epidemias. Hasta el momento, las pruebas ELISA para diagnóstico serológico de la infección se encuentran validadas en muestras de suero; sin embargo, en algunas ocasiones la cantidad o calidad de la muestra es inadecuada, o solo se tiene acceso a sangre anticoagulada tomada para el análisis de los parámetros hematológicos en el hemograma.Objetivo. Evaluar el desempeño de cuatro pruebas ELISA en muestras de suero y plasma de casos sospechosos de dengue.Materiales y métodos. Se procesaron 42 muestras —21 de suero y 21 de plasma— por las técnicas de ELISA de captura para IgM, ELISA de captura para IgG, ELISA indirecta para IgG y ELISA para la detección del antígeno viral NS1.Resultados. El porcentaje de muestras positivas encontrado fue IgM 33.3%, IgG Captura 33.3%, IgG Indirecta 90.5%, NS1 23.8%. El 42.9% de las muestras fueron positivas por RT-PCR (n=9). Todas las pruebas se comportaron igual tanto en sueros como plasmas (coeficiente Kappa 1.0).Conclusión. Los resultados obtenidos muestran una alta concordancia entre las mediciones realizadas en suero y en plasma, lo cual sugiere que la muestra de plasma puede utilizarse para el diagnóstico y la confirmación de los casos de dengue. Introduction. Appropriate dengue laboratory diagnosis is an important tool to manage the disease, as well to control possible outbreaks. Currently, ELISA dengue serological tests are validated to use with serum, however sometimes samples quality or quantity is inappropriate or there is only availability of anti-coagulated blood samples which have been used in total blood tests —haemogram—.Objective. To assess the performance of four dengue ELISA tests in serum or plasma samples obtained from presumptive dengue cases.Methodology. Forty two samples, 21 of serum and plasma each, were processed to dengue Capture IgM ultramicro-ELISA, Capture IgG ELISA, Indirect IgG ELISA and NS1 antigen ELISA. Nine out of 21 patients were diagnosed as dengue cases following the diagnostic algorithm.Results. The percentage of positive samples found was Capture IgM 33.3%, Capture IgG 33.3%, Indirect IgG 90.5% and NS1 dengue antigen 23.8%. Comparing the results between all ELISA tests it can be said that they had similar performances both in serum and plasma, the Kappa coefficient obtained was 1.0.Conclusions. These results show a high concordance between the measurements carried out in serum and plasma, which leads to suggest the latter may be used as a tool in the diagnosis and confirmation of dengue cases.

Background The neurological manifestations of dengue disease are occurring with greater frequency, and currently, no information is available regarding the reasons for this phenomenon. Some viruses infect and/or alter the function of endothelial organs, which results in changes in cellular function, including permeability of the blood-brain barrier (BBB), which allows the entry of infected cells or free viral particles into the nervous system. Methods In the present study, we standardized two in vitro models, a polarized monolayer of mouse brain endothelial cells (MBECs) and an organized co-culture containing MBECs and astrocytes. Using these cell models, we assessed whether DENV-4 or the neuro-adapted dengue virus (D4MB-6) variant infects cells or induces changes in the structure or function of the endothelial barrier. Results The results showed that MBECs, but not astrocytes, were susceptible to infection with both viruses, although the percentage of infected cells was higher when the neuro-adapted virus variant was used. In both culture systems, DENV infection changed the localization of the tight junction proteins Zonula occludens (ZO-1) and Claudin-1 (Cln1), and this process was associated with a decrease in transendothelial resistance, an increase in macromolecule permeability and an increase in the paracellular passing of free virus particles. MBEC infection led to transcriptional up-regulation of adhesion molecules (VCAM-1 and PECAM) and immune mediators (MCP-1 and TNF- α) that are associated with immune cell transmigration, mainly in D4MB-6-infected cells. Conclusion These results indicate that DENV infection in MBECs altered the structure and function of the BBB and activated the endothelium, affecting its transcellular and paracellular permeability and favoring the passage of viruses and the transmigration of immune cells. This phenomenon can be harnessed for neurotropic and neurovirulent strains to infect and induce alterations in the CNS.

Objective: To characterize a neuron-enriched primary TG culture and evaluate interferon- β expression and activity after HSV-1 infection. Materials and methods: The percentage of neurons present in cultures was assessed by neurofilament immunocytochemistry. Cultures were treated with interferon- β and infected with HSV-1, then viral antigen positive cells were counted and interferon- βexpression was assessed by quantitative PCR. Results: The culture contained 15% neurons and 85% non-neuronal cells. A cytopathic effect was observed, associated with high viral spread (72.9% neurons and 48.3% non-neuronal cells were positive for viral antigen). Interferon- β treatment impaired the cytopathic effect and decreased the infected neurons to 16.7% and infected non-neuronal cells to 7.8%. Viral infection at 6 h postinfection significantly increased the interferon- β transcripts by 18.2 fold, while at 18 h postinfection Interferon pre-treatment in infected cultures increased interferon- β transcription by 3.7 fold. Discussion: This culture model contained 15% neurons, which is 10 times higher compared to other reported cultures, and non-neuronal cells comprised 85% of cells in this culture. All types of cells were found to be infected, which is similar to that reported during acute infections in vivo . Additionally, interferon- βdecreased the infected cells, avoiding the cytopathic effect, which is similar to that reported in swine TG cultures. Conclusions: A neuron-enriched primary TG model was characterized. Interferon- β treatment protected cells from cytopathic effects and viral spread, while viral infection up-regulated interferon- β expression. This result means that interferon- β exerts an important antiviral effect against HSV-1 in these cultures. Objetivo: Caracterizar un cultivo primario de ganglio trigeminal (GT) enriquecido en neuronas y evaluar la expresión de interferón- y su actividad frente a la infección con Herpes simple tipo 1 (HSV-1). Materiales y métodos: El porcentaje de neuronas fue determinado por inmunocitoquímica para neurofilamento. Los cultivos fueron tratados con interferón- β e infectados con HSV-1, y se cuantificaron las células positivas para antígeno viral por inmunocitoquímica y la expresión de interferón- β por PCR cuantitativa. Resultados: El cultivo presentó un 15% de neuronas y 85% de células no neuronales. Se encontró efecto citopático, asociado a una alta diseminación de la infección (72,9% neuronas y 48,3% de células no neuronales positivas para antígeno viral). El interferón- β evitó la aparición de efecto citopático y disminuyó las células infectadas a 16,7% en neuronas y a 7,8% las células no neuronales. La infección viral incrementó la expresión de transcritos de interferón- β 18,2 veces a las 6 h de infección, mientras que a las 18 h post infección el tratamiento con interferón incrementó esta expresión 3,7 veces. Discusión: Los cultivos presentaron un 15% de neuronas, lo cual es 10 veces más que en otros cultivos reportados. Las células no neuronales representan el 85% de las células del cultivo, y se evidenció que todos los tipos de células se infectaron; similar a lo que ha sido reportado durante infecciones agudas in vivo . Adicionalmente, el interferón- β disminuyó el porcentaje de células infectadas y evitó la aparición de efecto citopático, similar a lo que ha sido reportado en cultivos de GT porcino. Conclusiones: Se caracterizó un modelo de cultivo primario de GT enriquecido en neuronas. Interferón- β protegió las células del efecto citopático y la diseminación viral mientras que la infección viral incrementó la expresión de interferón- β. Por lo tanto, el interferón- β ejerció un papel antiviral importante frente al HSV-1 en estos cultivos.

La infección por el virus de dengue es la enfermedad viral transmitida por insectos más importante del mundo que genera grandes gastos a los sistemas de salud. En Colombia, en más de 600 municipios está presente el mosquito vector y se ha detectado la circulación de los cuatro serotipos del virus, haciendo previsible que la incidencia y prevalencia sigan aumentando. Aunque se han hecho grandes avances y desarrollos para entender la enfermedad, existen vacíos científicos y técnicos que dificultan su correcto diagnóstico y que debilitan tanto la vigilancia en salud pública como la correcta atención en las instituciones prestadoras de salud. En este documento se revisan los principios e interpretaciones de las herramientas de laboratorio disponibles para el diagnóstico de dengue, haciendo énfasis en las dificultades existentes para la correcta definición de los casos desde el laboratorio general y especializado. Se explican los fundamentos y limitaciones de las técnicas de ELISA de captura de anticuerpos IgM, serología para IgG, detección del antígeno viral NS1, aislamiento viral en cultivos celulares y las pruebas más recientes basadas en la inmunocromatografía –pruebas rápidas–. La revisión se propone, además de aportar a la discusión sobre las dificultades para el diagnóstico en dengue, ofrecer una idea actualizada sobre cómo abordar el diagnóstico tanto en los laboratorios de salud pública como en los laboratorios especializados y contribuir así a mejorar los estándares de atención de los pacientes, reducir el impacto de la enfermedad y favorecer su control. Dengue is an infection caused by dengue virus and is the most important arthropod transmitted viral disease in the world, causing near 100 million cases and 50 000 fatalities each year. Health authorities believe that these numbers will grow in coming years. In Colombia, almost 600 municipalities are in regions with Aedes aegypti circulation, and the presence of four dengue serotypes has been demonstrated. Despite the increasing knowledge about disease pathogenesis and the dengue virus, some technical or scientific difficulties with diagnosing dengue remain, negatively affecting both public health surveillance and the appropriate attention to patients in health settings and hospitals. This paper reviews the principles and developments of the current diagnostic techniques for dengue, pointing out the difficulties with making accurate dengue diagnoses and case confirmations in public health and specialized laboratories. The principles and limitations of MAC-ELISA, IgG serology, viral NS1 detection and viral isolation by cell culture are presented. In addition, the review of immunochromatography techniques (rapid diagnostic tests) that have been put forward to help the point-of-care diagnosis is proposed. This paper is intended to bring forward some points of view about the issues related to dengue diagnosis and contribute to improve the discussion surrounding the strategies and techniques needed for reducing the impact of the disease and favoring its control.

No existen modelos animales apropiados para el estudio de la fisiopatología y las manifestacio- nes clínicas de la enfermedad causada por la infección con virus dengue, por lo que para ello se requiere desarrollar modelos experimentales. El propósito del presente trabajo fue establecer un modelo de infección in vitro con virus dengue serotipo-2 (DENV-2). Para esto se obtuvieron células mononucleares de sangre periférica (CMSP) usando un gradiente de Ficoll, y se las culti- vó e infectó con DENV-2 a una baja multiplicidad de infección. La subpoblación celular que se infectó y produjo citocinas se identificó empleando un análisis multiparamétrico por citometría de flujo. Como resultado, las CMSP fueron permisivas a la infección, que se detectó a las 24 horas de inoculado el virus. Además, en este mismo tiempo, los monocitos CD14+, pero no los linfo- citos CD3+ o CD19+, fueron la subpoblación celular preferencialmente infectada y responsable de la producción de TNF-α e IL-6. En conclusión, se estableció un modelo de infección in vitro usando CMSP no fraccionadas, en el que se identificó a los monocitos CD14+ como la principal célula blanco de la infección con DENV-2 y productora de citocinas proinflamatorias. Introduction: Methicillin-resistant Staphylococcus aureus (MRSA) is able to colonize the human To date, there are no appropriate animal models for the study of the pathophysiology and clinical manifestations of the disease caused by dengue virus infection; therefore, experimen- tal models are required for that purpose. The objective of the present work was to establish a model of in vitro infection with DENV-2. To this end, human peripheral blood mononuclear cells (PBMC) were obtained using a Ficoll gradient, and infected with DENV-2 using a low multiplicity of infection. The cell populations infected and responsible for the production of cytokines were identified using a multiparametric analysis by flow cytometry. As a result, PBMC were permissive to infection that was detected 24 hours after virus inoculation. Additionally, at this same time, CD14+ cells, but not CD3+ or CD19+ cells, were preferentially infected and responsible for the production of TNF-α and IL-6. In conclusion, we established a model of in vitro infection using unfrac-tionated PBMC, in which CD14+ cells were identified as the primary target cells for infection with DENV-2, and the production of proinflammatory cytokines.

El sistema nervioso (SN), está protegido por una barrera de difusión celular conocida como Barrera Hematoencefálica (BHE), compuesta por diferentes tipos de células que limitan el paso de moléculas desde los capilares hacia el parénquima cerebral, lo cual garantiza la homeostasis del tejido. A pesar de esto, algunas moléculas y agentes infecciosos logran atravesar la BHE e ingresar al tejido nervioso para inducir graves daños en la fisiología de este. Dentro de los patógenos que logran alterar la BHE e infectar el tejido nervioso, se encuentran algunos miembros de la familia flaviviridae típicamente neurotrópicos, sin embargo el virus del dengue (DENV), un virus considerado no neurotrópico, puede infectar y alterar la fisiología del tejido nervioso ocasionando signos como encefalitis, parálisis y alteraciones motoras y cognitivas que pueden ser permanentes. Para comprender los cambios de tropismo y los factores neurológicos e inmunológicos asociados a la neuroinfección por DENV, en nuestro laboratorio se desarrolló un modelo de neuroinfección en ratones lactantes utilizando una cepa de virus neuroadaptado (D4MB-6), que infecta neuronas y otras células del tejido nervioso e induce la alteración de la BHE en ratones lactantes. Por lo tanto, el presente proyecto buscó evaluar en un modelo de BHE in vitro, si la alteración de la permeabilidad de la barrera endotelial cerebrovascular asociada a la infección con el DENV-4 neuroadaptado o no, favorece el paso de virus libre o asociado a células del sistema inmune lo cual, permitiría la infección y dispersión viral en el tejido nervioso. Para esto, se estableció un modelo de BHE in vitro en monocapa o co-cultivo utilizando cultivos primarios de endotelio cerebrovascular con o sin astrocitos obtenidos a partir de cerebros de ratones lactantes, siendo únicamente las células endoteliales susceptibles a la infección con el virus parental o D4MB-6. Los resultados obtenidos mostraron en ambos modelos de BHE que a las 10 horas post-infección (hpi) con cada virus, hubo una disminución en los valores de resistencia transendotelial (TEER), asociada a un aumento en la permeabilidad. Adicionalmente en este mismo tiempo post infección se detectaron partículas virales infecciosas en la cámara inferior de los insertos, lo que sugiere que la infección ocasionó una alteración en la integridad de las células endoteliales, lo que permitió el paso paracelular de las partículas virales. Se encontró que la infección con el D4MB-6 indujo la relocalización -sin afectar la expresión-, de la proteína ZO-1 y un aumento en la expresión de los transcritos para las proteínas VCAM, PECAM, TNFα y MCP-1 comparado con lo observado durante la infección con el virus parental. Esto último está relacionado con un proceso de activación endotelial que al parecer favoreció el proceso de transmigración de monocitos/macrófagos J774 en ambos modelos de BHE estandarizados. Lo anterior convierte el proceso de alteración de la BHE en uno de los posibles mecanismos utilizados por el DENV para ingresar y dispersarse dentro del tejido nervioso. Magíster en Ciencias Básicas Biomédicas Maestría The nervous system (NS) is protected by a cellular diffusion barrier named Blood Brain Barrier (BBB). This barrier is formed by different cell types that limit the passage of molecules from the capillaries into the brain parenchyma, nevertheless some molecules and infectious agents are able to cross the BBB and infect the nervous tissue. Among the viruses that manage to alter the BBB and infect nervous tissue, there are some flaviviridae family members known as neurotropic flavivirus, however Dengue virus (DENV), a no-neurotropic flavivirus, can alter the physiology of the nervous tissue, causing clinical signs such as encephalitis, paralysis and motor and cognitive alterations that might be permanent. To understand some of the changes in the virus tropism, and in the neurological and immunological factors associated with DENV infection in the NS, we developed a neuroinfection model in suckling mice using a strain of neuroadapted virus (D4MB-6) than infects neurons and some others cells of the nervous tissue and can alter the BBB permeability in suckling mice. Therefore, the present project evaluated the permeability alteration of the cerebrovascular endothelial barrier, associated with DENV-4 or D4MB-6 infection in an in vitro BBB model. We tried to answer if this alteration can promote the passage of virus into the nervous tissue allowing infection and viral spread. We establish a BBB in vitro model using primary cultures (isolated from suckling mice) of endothelial cells (BBB model in monolayer) or endothelial cells and astrocytes (co-culture BBB model). The results showed that only the endothelial cells were susceptible to the infection with each evaluated virus; also in both BBB models at 10 hours post-infection, there was a decreased in the transendothelial resistance values (TEER), associated with an increase in the permeability of the model. Additionally at this time, we detected infectious viral particles in the supernatants of the lower chamber of the inserts, suggesting that infection results in an alteration in the integrity of the endothelial cells and permits the paracellular passage of viral particles. We also found that the infection with D4MB-6 induced the relocation of the ZO-1 protein, but it did not affect the expression pattern of this protein. Infection also induced the over expression of primary transcripts of VCAM, PECAM, TNFα y MCP-1 proteins, compared with the observations made when the cells were infected with DENV-4. This is related with an endothelial activation process that favored the transmigration of immune cells (J774) in both BBB models. Our results suggest that the alteration process of the BBB is one of the possible mechanisms used by the DENV to enter and spread in to the nervous tissue.

Introducción. El dengue es una enfermedad humana producida por el virus del mismo nombre, que se transmite por la picadura de mosquitos del género Aedes. La infección tiene una amplia gama de presentaciones clínicas que van desde la ausencia de síntomas hasta los casos fatales y afecta principalmente a la población pediátrica. Según la nueva clasificación de la enfermedad, las manifestaciones neurológicas se consideran un criterio para el diagnóstico del dengue grave. Objetivo. Evaluar los posibles mecanismos involucrados en la aparición de los signos neurológicos en una línea celular de neuronas humanas, como modelo de infección con el virus del dengue del serotipo 2 (DENV-2). Materiales y métodos. Se evaluó la sensibilidad y la permisividad de la línea celular SH-SY5Y a la infección por el DENV-2; se encontró que la proporción entre infección y producción viral era similar a las de las células de primates usadas como control positivo de la infección. Resultados. La infección indujo un efecto citopático en la línea celular de neuroblastoma caracterizado por un proceso de muerte apoptótica, con aumento en la proporción de células positivas al emplear los métodos de anexina V y TUNEL. Se encontró una regulación positiva del factor de necrosis tumoral alfa (TNF-α), y el tratamiento con un anticuerpo anti-TNF-α aumentó ligeramente la supervivencia de las células infectadas. La adición de TNF-α exógeno a los cultivos infectados potenció la muerte celular. Conclusión. Estos resultados sugieren, en su conjunto, que la regulación positiva del TNF-α podría hacer parte del proceso que induce daño y muerte celular durante el desarrollo de la encefalitis por dengue. Introduction: Dengue is a human disease caused by a virus with the same name, which is transmitted by the bite of Aedes mosquitoes. The infection has a wide range of clinical presentations ranging from asymptomatic to fatal cases, with the pediatric population being the most susceptible. According to the new classification of the disease, the neurological manifestations are considered a criterion for the diagnosis of severe dengue Objective: To evaluate the possible mechanisms involved in the onset of neurological signs in a cell line of human neurons as a model of infection with dengue virus type 2 (DENV-2). Materials and methods: Susceptibility and permissiveness of the SH-SY5Y line to infection by DENV-2 was analyzed, showing that the proportions of viral infection and production are similar to those of primate cells used as positive control for infection. Results: Infection induced a cytopathic effect on the neuroblastoma line characterized by apoptotic cell death process, increasing the proportion of annexin V and TUNEL positive cells and an upregulation of TNF-α. Treatment with anti-TNF-α antibody increased slightly cell survival of infected cells. The addition of exogenous TNF-α to the infected cultures enhanced cell death. Conclusion: These results as a whole suggest that the upregulation of TNF-α could be part of the process that induces cell damage and death in cases of dengue encephalitis.

Although neurological manifestations associated with dengue infections have been reported in endemic countries, the viral or host characteristics determining the infection or alteration of nervous function have not been described. In order to investigate neurobiological conditions related to central nervous system dengue virus (DENV) infection, we established a mouse model of neuroinfection. A DENV-4 isolate was first adapted to neuroblastoma cells, later inoculated in suckling mice brain, and finally, this D4MB-6 viral variant was inoculated intraperitoneally in Balb/c mice at different postnatal days (pnd). Virus-induced fatal encephalitis in 2 and 7 pnd mice but infected at 14 and 21 pnd mice survived. The younger mice presented encephalitis at the sixth day postinfection with limb paralysis and postural instability concomitant with efficient viral replication in brain. In this mice model, we found activated microglial cells positive to viral antigen. Neurons, oligodendrocytes, and endothelial cells were also infected by the D4MB-6 virus in neonatal mice, which showed generalized and local plasma leakage with blood–brain barrier (BBB) severe damage. These results suggest that there was a viral fitness change which led to neuroinfection only in immune or neurological immature mice. Infection of neurons, endothelial, and microglial cells may be related to detrimental function or architecture found in susceptible mice. This experimental neuroinfection model could help to have a better understanding of neurological manifestations occurring during severe cases of dengue infection.