Increased cytokine/chemokines in serum from asthmatic and non-asthmatic patients with viral respiratory infection.

BACKGROUND: Respiratory viral infections can induce different cytokine/chemokine profiles in lung tissues and have a significant influence on patients with asthma. There is little information about the systemic cytokine status in viral respiratory-infected asthmatic patients compared with non-asthmatic patients. OBJECTIVES: The aim of this study was to determine changes in circulating cytokines (IL-1ß, TNF-α, IL-4, IL-5) and chemokines (MCP1: monocyte chemoattractant protein-1 and RANTES: regulated on activation normal T cell expressed and secreted) in patients with an asthmatic versus a non-asthmatic background with respiratory syncytial virus, parainfluenza virus or adenovirus respiratory infection. In addition, human monocyte cultures were incubated with respiratory viruses to determine the cytokine/chemokine profiles. PATIENTS/METHODS: Patients with asthmatic (n = 34) and non-asthmatic (n = 18) history and respiratory infections with respiratory syncytial virus, parainfluenza, and adenovirus were studied. Healthy individuals with similar age and sex (n = 10) were used as controls. Cytokine/chemokine content in blood and culture supernatants was determined by ELISA. Monocytes were isolated by Hystopaque gradient and cocultured with each of the above-mentioned viruses. RESULTS: Similar increased cytokine concentrations were observed in asthmatic and non-asthmatic patients. However, higher concentrations of chemokines were observed in asthmatic patients. Virus-infected monocyte cultures showed similar cytokine/chemokine profiles to those observed in the patients. CONCLUSIONS: Circulating cytokine profiles induced by acute viral lung infection were not related to asthmatic status, except for chemokines that were already increased in the asthmatic status. Monocytes could play an important role in the increased circulating concentration of cytokines found during respiratory viral infections.

Respiratory syncytial virus infection increases regulated on activation normal T cell expressed and secreted and monocyte chemotactic protein 1 levels in serum of patients with asthma and in human monocyte cultures.

BACKGROUND: Respiratory syncytial virus (RSV) infection is associated to episodic exacerbations of asthma involving alveolar macrophages and chemokine production. OBJECTIVE: The aim of this study was to determine the circulating levels of monocyte chemotactic protein 1 (MCP-1), regulated on activation normal T cell expressed and secreted (RANTES), and substance P (SP) in patients with and without asthma with acute respiratory RSV infection and the chemokine profile in RSV- infected monocyte cultures from normal individuals and individuals with asthma. METHODS: In this regard, 31 adult patients with acute respiratory infection (15 patients with asthma) were studied. MCP-1, RANTES and SP were measured in serum and in supernatants from monocyte cultures by enzyme-linked immunosorbent assay (ELISA). RESULTS: Increased levels of MCP-1 and RANTES were observed in serum from patients with asthma related to RSV infection. RSV-infected monocyte cultures from healthy individuals showed increased content of those chemokines, and monocyte cultures from patients with asthma showed increased expression of MCP-1. CONCLUSION: These data show that RSV infection induces increased circulating level of chemokines in patients with asthma, and this finding could be mediated in part by the interaction virus-monocyte.

Increment of interleukin 6, tumour necrosis factor alpha, nitric oxide, C-reactive protein and apoptosis in dengue.

This study evaluated the levels of TNFalpha, IL-6, IL-1beta, nitric oxide (NO), CRP, C3 and apoptosis in 36 patients with dengue fever (DF), 34 patients with dengue haemorrhagic fever (DHF) and in virus-infected monocyte cultures. IL-6, TNFalpha, NO (nitrites) and CRP levels were increased and C3 diminished in patients with DF and DHF. IL-6, TNFalpha, CPR and C3 values were associated with disease severity (DHF). Nitrite content was incremented in DF patients. TNFalpha, NO and CRP levels were associated with secondary infection. IL-6 and CRP levels were associated with dengue virus type 4 (DENV-4) and DENV-2, respectively. Low levels of C3 were associated with DENV-2 and DENV-4 infections. Similarly, increased content of TNFalpha, IL-6 and nitrites were observed in supernatants from infected monocyte cultures. IL-6 was associated with DENV-4 infection. The different virus serotypes induced apoptosis in monocyte cultures. Dengue infection did not induce elevated IL-1beta production, either in patients or in infected cultures. These results suggest that TNFalpha, IL-6, NO and CRP are involved in dengue infection and that monocytes could be an important source of cytokine and NO production.

Etiología viral de las infecciones respiratorias agudas / Viral etiology of acute respiratory infections

Las infecciones respiratorias agudas (IRA) son patologías que afectan el tracto respiratorio desde la faringe proximal hasta los pulmones, con una evolución de menos de 15 días y constituyen la causa más frecuente de morbimortalidad en el mundo. Con la finalidad de identificar los agentes virales asociados a este tipo de infecciones en pacientes del estado Zulia, Venezuela, entre febrero 2005 y julio de 2006, se estudiaron un total de 102 muestras provenientes del tracto respiratorio (hisopado nasal, faríngeo y/o nasofaríngeo, esputo y lavado broncoalveolar) de pacientes con clínica de IRA. El aislamiento viral se realizó a través del cultivo celular y la identificación del agente patógeno por la técnica de inmunofluorescencia directa. Se obtuvieron 46 muestras positivas (45%), la incidencia estuvo homogéneamente distribuida en todos los grupos de estudio aun cuando se observó predominio en el grupo de 41 a 64 años, seguido de los lactantes. No hubo diferencias significativas en cuanto al sexo. Dentro de los patógenos virales aislados el Virus Sincicial Respiratorio (VSR) fue el agente con mayor frecuencia (32,6%) (p<0,05), seguido de Adenovirus (28,2%), Parainfluenza (23,9%) e Influenza (15,2%). Las infecciones respiratorias del tracto inferior fueron las más frecuentes (67,4%). Se demuestra una alta incidencia de agentes virales asociados a IRA en el estado Zulia. Se destaca la alta frecuencia en pacientes adultos y la mayor positividad para VSR.

Acute respiratory infections (ARI) are pathologies that affect the respiratory tract from the proximal pharynx to the lungs, with an evolution of less than 15 days. They constitute the most frequent cause of morbimortality in the world. With the purpose of identifying the viral agents associated to this type of infections in patients of Zulia State, Venezuela, between February 2005 and July 2006, a total of 102 samples of the respiratory tract (oropharyngeal swab, nasopharyngeal swab, nasopharyngeal washing, spit and bronchoalveolar lavage) were studied. Viral isolation was made through a cellular culture and the identification of the pathogenic agents by the technique of direct immunofluorescence. Forty six positive samples were obtained (45%). The greater incidence was found in the groups of 41 to 64 years old patients, followed by lactanting babies (1 to 23 months). There were no significant differences between sexes. Within the isolated viral pathogens, Respiratory Syncytial Virus (RSV) was the agent most frequently found (32.6% p<0.05), followed by Adenovirus (28.2%), Parainfluenza (23.9%) and Influenza (15.2%). The respiratory infections of the low respiratory tract were the most frequent (67.4%). A high incidence of associated viral agents to ARI in Zulia State is demonstrated. A high incidence in adult patients and the greatest positivity was found for RSV.

Antagonistic effect of luzindole in mice treated with melatonin during the infection with the venezuelan equine encephalomyelitis virus.

The effect of Luzindole (LZ) in mice treated with melatonin (MEL) during the infection with the Venezuelan equine encephalomyelitis (VEE) virus was examined. Melatonin (500 microg/Kg b.w.) was administered daily 3 days before and 5 days after the infection. Luzindole (5 mg/Kg b.w.) was injected intraperitoneally 3 days before (pre-infection) or 5 days after (post-infection) the infection. Mortality rates in the infected mice treated both with MEL and LZ were higher than in those treated with MEL alone in which the lowest brain and serum viral titers were detected. On the third post-infection day, viral titers of the MEL + VEE + LZ (pre-infection) group were higher than those of the remainder groups. On the fifth day, viral titers in infected mice were similar to those of the MEL + VEE + LZ (pre-infection) group, but higher than those detected in the MEL + VEE + LZ (post-infection). In conclusion, the protective effect of MEL in mice infected with VEE virus was inhibited by LZ suggesting that this protection is mediated by MEL receptors.

Incremento de interleucina-1 beta, interferon gamma y factor de necrosis tumoral alfa en suero y cerebro de ratones infectados con el virus de encefalitis equina venezolana / Increase of interleukin-1 beta, gamma interferon and tumor necrosis factor alpha in serum and brain of mice infected with the venezuelan equine encephalitis virus

Diversos esfuerzos han sido dirigidos a fin de esclarecer los principales mecanismos de protección y recuperación en las infecciones virales agudas y el posible papel de las citocinas involucradas en la respuesta inmunitaria primaria inducida por una cepa epizoótica del virus de Encefalitis Equina Venezolana (EEV). En el presente estudio se determinaron las concentraciones de citocinas TH1 Interleucina-2 (IL-2) e Interferon-gamma (IFN-g), TH2 Interleucina-4 (IL-4), proinflamatorias (IL-1b) y el Factor de Necrosis Tumoral -alfa (TNF-a) en suero y cerebro de ratones infectados con el virus de EEV a diferentes períodos de infección. Se utilizaron ratones NMRI albinos machos infectados con una suspensión (10 DL50) de la cepa Guajira del virus de EEV, y un grupo control (sin infectar). En los días 1, 3 y 5 post-infección, se extrajo sangre completa de ratones para la obtención de suero y el cerebro previa perfusión, para la obtención de homogeneizados cerebrales. En ambas muestras se determinaron IL-2, IFN-g, IL-4, IL-1b, y TNF-a por la técnica de ELISA. Se observó un incremento significativo (p < 0,01) en suero y homogeneizados cerebrales al 1er, 3er y 5to día post-infección en las concentraciones de IL-1b, IFN-g y TNF-a, al compararlos con el grupo control. La cuantificación de IL-2 e IL-4, no arrojaron diferencias estadísticamente significativas al ser comparados con los controles. Estos resultados sugieren que la IL-1b, IFN-g y TNF-a, podrían estar involucradas en la respuesta inmunitaria temprana al virus de EEV durante la infección primaria.

[Increase of interleukin-1 beta, gamma interferon and tumor necrosis factor alpha in serum and brain of mice infected with the Venezuelan Equine Encephalitis virus]. / Incremento de interleucina-1 beta, interferon gamma y factor de necrosis tumoral alfa en suero y cerebro de ratones infectados con el virus de Encefalitis Equina Venezolana.

Considerable efforts have been directed to clarify the main protective and recovery mechanisms in acute viral infections and, the possible role of the cytokines involved in the primary immune response induced by an epizootic strain of the Venezuelan Equine Encephalitis (VEE) virus. This study examined the levels of TH1 cytokines Interleukin-2 (IL-2) and Interferon-gamma (IFN-gamma), TH2 cytokines Interleukin-4 (IL-4) and proinflammatory cytokines (IL-1beta, TNF-alpha) in serum and brain of mice infected with the VEE virus during different post infection periods. NMRI albino male mice infected with a suspension (10 DL50) of the Guajira strain of the VEE virus, and a control group (without infection) were used. At one, 3 and 5 days post-infection, whole blood and brains were extracted to obtain sera and brain homogenates, respectively. IL-2, IFN-gamma, IL-4, IL-beta and TNF-alpha were determined by ELISA. A significant increment in the levels of IL-1beta, IFN-gamma and TNF-alpha was observed (p<0.01) in serum and brain homogenates at 1, 3 and 5 day post-infection, when compared with the control group. The levels of IL-2 and IL-4 did not show any significant statistical difference when compared to the controls. These results suggest that IL-1beta, IFN-gamma and TNF-alpha, could be involved in the early immunitary response to VEE virus during the primary infection.

Anticuerpos séricos antiglicolípido fenólico 1 en personal de centros de salud en contacto con pacientes con enfermedad de Hansen / Antiphenolic glycolipid-1 antibodies in personnel in health centers in contact with Hansen´s disease patients

La lepra es una enfermedad con diferentes formas clínicas, sin embargo, es poco el conocimiento que se tiene sobre portadores de Mycobacterium leprae (M. leprae), así como de su transmisión y los fenómenos inmunológicos que conllevan a la aparición de la enfermedad. El antígeno Glicolípido Fenólico 1 (PGL-1) es un factor de virulencia, específico del M. leprae que protege a la bacteria del ataque de los macrófago. El objetivo principal de la siguiente investigación fue detectar anticuerpos anti PGL-1 en el personal en contacto estrecho con pacientes con lepra, para conocer su grado de exposición al bacilo y su utilidad como factor de riesgo para sufrir la enfermedad. Se seleccionó un grupo de individuos (n: 52) en contacto frecuente con pacientes leprosos y un grupo control (n: 60) sin contacto demostrado. La presencia de anticuerpos séricos IgM anti PGL-1 se determinó por la técnica de ELISA. Del total analizado, se detectaron anticuerpos anti-PGL-1, en 22 muestras (42,3%) del grupo expuesto y 3 (5,0%) en el grupo control (p<0,05). No se observaron diferencas en relación al sexo (45,5% vs. 41,5%). Se encontró un predominio de la seropositividad en el personal entre 36 a 55 años, sin relación a los años de exposición. Se destaca una mayor frecuencia en el personal médico (73,3%) y un riesgo relativo de exposición al bacilo de la Lepra del 1.9 en la población expuesta. Estos resultados demuestran un mayor porcentaje de personas seropositivas al anti-PGL-1 en el personal de centros de salud, relacionado al grado de exposición al bacilo de Hansen, especialmente el personal médico. Hallazgos que sugieren riesgo incrementado de adquirir M. leprae con respecto a la población general. Se recomienda la toma de medidas de bioseguridad, así como realizar un seguimiento serológico de los casos positivos del presente estudio.

Capacidad larvívora del gold fish (Carassius auratus auratus) y del guppy salvaje (Poecilia reticulata) sobre larvas de Aedes aegypti en condiciones de laboratorio / Larvivorous capacity of the gold fish (Carassius auratus auratus) and the wild guppy (Poecilia reticulata) on larvaes of Aedes aegypti in laboratory conditions

El control biológico de vectores de importancia médica se presenta como una alternativa al uso de plaguisidas. La utilización de peces larvívoros se promueve como una nueva estratégia para el control de vectores. El propósito de este estudio es evaluar el potencial de dos especies ícticas para el control biológico de mosquitos Aedes aegypti (principal vector de dengue) en condiciones de laboratorio. Un creciente número de larvas de A. aegyptis en estadíos I, II y III (n: 25, 50, y 100) fueron colocados en acuarios con goldfish (Carassius auratus) y guppys salvajes (Poecilia reticulata). Se cuantificó la relación peso corporal/larvas ingeridas/hora en diez ensayos. La especie Poecilia reticulata reflejó una mayor (P<0,001) capacidad larvívora que C. auratus, dado que cuando se administraron 25, 50 y 100 larvas, los Poecilia reticulata obtuvieron valores promedio de eliminación de 3,15 ± 0,12; 5,50 ± 0,31 y 10,95 ± 0,25, respectivamente, frente a 1,21 ± 0,03; 2,45 ± 0,02 y 4,73 ± 0,06 de los C. auratus. Los resultados obtenidos son indicativos de que bajo las condiciones ensayadas, ambas especies de peces poseen alta capacidad de eliminación de larvas de mosquito A. aegypti; sin embargo, consederando su capacidad larvívora, disponibilidad, costo, características reproductivas y resistencia a las condiciones climáticas, la especie Poecilia reticulata ofrece ventajas importantes ante C. auratus auratus cuando ambos se evalúan integralmente como controladores poblacionales de mosquitos vectores.

Melatonin decreases nitric oxide production, inducible nitric oxide synthase expression and lipid peroxidation induced by Venezuelan encephalitis equine virus in neuroblastoma cell cultures.

Increased expression of inducible nitric oxide synthase has been shown in murine Venezuelan equine encephalitis (VEE) virus infection. In this experimental model, melatonin (MTL) treatment has shown to be beneficial. The aim of this study was to determine the effect of VEE virus on the nitric oxide (NO) production and lipid peroxidation in neuroblastoma cell cultures, and to investigate the role of MTL during cell-virus interaction. Neuroblastoma cells were co-cultured with VEE virus and treated with MTL at doses ranging from 0 to 1.8 mM, for 6, 12, 24 and 48 h. NO and lipid peroxidation were measured in culture supernatants and in the cellular content by nitrite concentration and thiobarbituric acid assay, respectively. Expression of inducible nitric oxide synthase (iNOS) was determined by indirect immunofluorescence. Increased production of NO and lipid peroxidation products were found in supernatants and cellular contents of VEE virus treated cultures. Both NO and lipid peroxidation were decreased by MTL treatment in a time dependent manner. Increased iNOS expression was observed in VEE virus infected cultures that was reduced by MTL treatment. These results could be related to the beneficial role of MTL in the VEE experimental disease and address the possible therapeutic potential of the hormone in human VEE virus infection.

In vitro, melatonin treatment decreases nitric oxide levels in murine splenocytes cultured with the venezuelan equine encephalomyelitis virus.

The purpose of this work was to determine the effect of melatonin on the nitric oxide levels in murine splenocytes cultured with the Venezuelan equine encephalomyelitis virus. After incubation, nitric oxide levels were measured by the diazotization assay. Those cultures with the Venezuelan equine encephalomyelitis virus increased nitric oxide levels. Splenocytes infected and treated with 100 and 150 microg/ml of melatonin, decreased significantly the nitric oxide levels when compared to infected and non-treated splenocytes. These findings show that splenocytes infected with the Venezuelan equine encephalomyelitis virus generate important amounts of nitric oxide and suggest that melatonin protects the mice infected with the Venezuelan equine encephalomyelitis virus by a mechanism involving the decreasing of nitric oxide concentrations in tissue.

[Hepatic alterations in patients with dengue]. / Alteraciones hepáticas en pacientes con dengue.

Clinical features of Dengue are very variable due to multiple alterations induced by the virus in the organism. Increased levels of transaminases similar to those produced by the Hepatitis virus have been reported in patients with Dengue from hiperendemic zones in Asia. The objectives of this study were to determine alterations in the liver tests in patients with Dengue and to relate them to the disease, clinically and serologically. Clinical history, hemathological tests serum transaminases (ALT y AST) and bilirubin assays were performed in 62 patients with clinical and serological diagnosis of Dengue. According to clinical features 38.7% of the patients with classical (CD) and hemorrhagic (DHF) forms of Dengue reffered abdominal pain and 2 patients with DHF had ictericia and hepatomegaly. Laboratory test findings showed leucopenia in 72.5% in both forms of Dengue and of patients with DHF severe thrombocytopenia (< 50.000 platelets x mm3), long PT and PPT in 70.9%, 23.0% and 42.3%, respectively. Transaminase values five fold higher than the normal values (p < 0.005) were observed in 36.8% and 74.4% of patients with CD and DHF respectively; AST was predominant in both groups. Our results suggest liver damage during the course of Dengue. A differential diagnosis has to be done between the hepatic involvement of Dengue cases and others viral diseases with hepatic disfunctions.

Alteraciones hepáticas en pacientes con dengue / Hepatic alterations in patients with dengue

La caracterización clínica del Dengue es muy variable debido a las múltiples alteraciones inducidas por el virus en el organismo. Se ha reportado incremento en los niveles de transaminasas similares a los producidos por el virus de Hepatitis en pacientes con Dengue de zonas hiperendémicas de Asia. Los objetivos del trabajo fueron determinar alteraciones en las pruebas de funcionalismo hepático en pacientes con Dengue y relacionar clínica y serológicamente la infección viral. A 62 casos con confirmación serológica para Dengue, se les realizó historia clínica, hematología completa, Tiempo de Protrombina (TP) y Tiempo Parcial de Tromboplastina (TPT), cuantificación de transaminasas (ALT y AST) y bilirrubina en suero. En relación a las características clínicas el 38,7 por ciento de los pacientes con Dengue Clásico (DC) y Fiebre Hemorrágica por Dengue (FHD) refirieron dolor abdominal y 2 con FHD presentaron hepatomegalia e ictericia. En los resultados de laboratorio se observó leucopenia (72,5 por ciento) en ambas formas de Dengue y en pacientes con FHD, trombocitopenia severa (<50.000×mm3) y TP y TPT alargados en 70,9 por ciento, 23,0 por ciento y 42,3 por ciento, respectivamente. El valor de transaminasas resultó hasta cinco veces más elevado que el valor normal (p<0,005) en 36,8 por ciento de los pacientes con DC y en 74,4 por ciento con FHD, con predominio de AST en ambos grupos. Los resultados sugieren daño hepático durante el curso del Dengue. Esto permite afirmar que la infección por virus Dengue puede causar disfunción hepática aguda y debe ser considerada en el diagnóstico diferencial con otras infecciones virales con disfunción hepática

Contribución del virus sincicial respiratorio y bacterias a la presencia de asma en una población adulta / Contribution of respiratory syncytial virus and bacteria to the prevalence of asthma in an adult population

El Virus Sincicial Respiratorio (VSR) es una de las causas más importantes de enfermedad de las vías respiratorias en infantes y preescolares. El VSR ha sido señalado como factor de riesgo en la aparición del asma bronquial en pacientes pediátricos, pero existen controversias sobre su papel en el asma del adulto. El presente estudio determinó la presencia del antígeno de VSR y bacterias en adultos asmáticos del estado Zulia, Venezuela. Se recolectaron 196 hisopados faríngeos (143 de pacientes asmáticos en crisis y 53 de no asmáticos). El antígeno del VSR fue determinado por la técnica de ELISA y la presencia de bacterias por técnicas bacteriológicas convencionales. En los pacientes asmáticos se encontró una incidencia de VSR de 42,65 por ciento, mientras que en el grupo control no se detectaron antígenos virales. En cuanto a las bacterias, los individuos asmáticos presentaron un mayor porcentaje (84,15 por ciento) de flora transitoria (p<0,001) como Streptococcus pyogenes y Escherichia coli que el grupo no asmático, en el que se aislaron estas bacterias en el 47,2 por ciento de los hisopados. La incidencia de VSR en pacientes asmáticos evidencia que este agente pudiera jugar un papel importante como factor de riesgo en la patogénesis del asma bronquial en el adulto. La presencia incrementada de bacterias patógenas en la microflora de la orofaringe de los pacientes asmáticos podría ser debido a la alteración del tracto bronquial por la infección viral, y consecuentemente constituir otro factor predisponente de esta enfermedad

Ultrastructural studies on dengue virus type 2 infection of cultured human monocytes.

BACKGROUND: Early interaction of dengue virus and monocyte/macrophages could be an important feature for virus dissemination after its initial entry via the mosquito vector. Since ultrastructural analysis of this interaction has not been reported, dengue type 2 (DEN2) virus-infected human monocyte cultures were studied at 1, 2, 4 and 6 hours after infection. RESULTS: Typical dengue particles and fuzzy coated viral particles were 35 to 42 nm and 74 to 85 nm respectively. Viruses were engulfed by phagocytosis and macropicnocytosis leading to huge vacuoles and phagosomes inside the monocytes. Interaction of monocytes with DEN2 virus induced apoptosis, characterized by nuclear condensation and fragmentation, cellular shrinkage, blebbing and budding phenomena and phagocytosis of apoptotic cells by neighboring monocytes. This finding was confirmed by TUNEL. Ultrastructural features associated to DEN2 virus replication were not observed. CONCLUSION: These data suggest that clearance of the virus by monocytes and cellular death are the main features during the initial interaction of DEN2 virus and monocytes and this could be important in the rapid elimination of the virus after infection by mosquito vector.

[Immunity to flavivirus in Amerindian population of the Sierra de Perijá, Zulia state, Venezuela]. / Inmunidad a flavivirus en la población indígena de la Sierra de Perijá, estado Zulia, Venezuela.

Little information is available about Flavivirus infection in amerindian populations in western Venezuela. On this account the activity and seroprevalence of these viruses were determined and the hypothesis concerning the existence of a sylvatic cycle, conditioning the infection transmission of these viruses in indigenous populations, was studied. For this, blood samples from Yukpas (n=144) and Barí (n=110) communities were collected, 35 (Yukpas=25 and Barí=10) of which were processed for viral isolation followed by RT-PCR. The anti-Flavivirus IgG antibodies were determined by ELISA. The results did not show active Dengue cases and the seroprevalence of anti-Flavivirus IgG in the Yukpa population was significantly higher (p < 0.0001) than in the Barí population (43.1% vs. 6.4%). The present study has determined the presence of Flavivirus immunity in Yukpa and Barí populations. These results show a higher prevalence at the former than in the Barí population, which suggests circulation of Flavivirus, mainly in the Yukpa communities, being scarce and sporadic in Barí villages. However, in the indigenous populations studied, the causes or factors that determine the off set of Flavivirus infections in these zones could vary. The detected prevalence between both communities may be due to differences in the structure settlements and social habits. No evidences were found to support the presence of a sylvatic cycle in the Flavivirus transmission, specially of Dengue, in this population.

Inmunidad a flavivirus en la población indígena de la Sierra de Perijá, estado Zulia, Venezuela / Immunity to flavivirus in amerindian population of the Sierra de Perijá, Zulia state, Venezuela

Existe poca información acerca de la infección por Flavivirus en poblados amerindios del occidente de Venezuela, razón por la cual se determinó la actividad y seroprevalencia de los mismos y se analizó la hipótesis que sustenta la existencia de un ciclo selvático de transmisión de estas infecciones en poblaciones indígenas. Para ello, se recolectaron muestras de sangre en comunidades Yukpas (n = 144) y Barí (n = 110). De ellas, 35 muestras (Yukpas = 25 y Barí = 10) fueron procesadas por aislamiento en cultivo celular e identificación viral por RT-PCR. La determinación de anticuerpos IgG anti-Flavivirus se realizó a través de la técnica de ELISA. Los resultados obtenidos no evidenciaron casos activos de dengue y la seroprevalencia para IgG anti-Flavivirus en la población Yukpa fue significativamente mayor (p < 0,0001) que en la población Barí (43,1 vs 6,4 por ciento), evidenciándose inmunidad anti-Flavivirus en ambas poblaciones indígenas. Estos resultados muestran la existencia de una mayor seroprevalencia de Flavivirus en los Yukpas que en los Barí, lo cual sugiere una actividad contínua de estos virus, principalmente en la población Yukpa. Sin embargo, en estas poblaciones las causas o factores que condicionan la presencia o llegada de casos son variadas y, posiblemente, están relacionadas con la estructura de los poblados y los hábitos de intercambio social. No se evidenció característica alguna que apoyara la presencia de un ciclo selvático en la transmisión de estos virus, especialmente del dengue, en esta población

Seroprevalencia de la encefalitis equina venezolana en una población de équidos del estado Zulia Venezuela 1999-2001 / Seroprevalence of the venezuelan equine encephalitis of equidae population of Zulia state Venezuela 1999-2001

El propósito de este estudio fue determinar la prevalencia de anticuerpos contra EEV en la población de équidos de los municipios Mara, Almirante Padilla, Páez, Miranda y Santa Rita del estado Zulia, Venezuela. Muestras de sangre de 1380 équidos fueron recolectadas entre enero 1999 y febrero 2001. La lgG anti-EEV fue detectada a través de un ensayo inmunoenzimático (ELISA). Los resultados muestran una seroprevalencia general del 38,6 por ciento (532 de 1380). La prevalencia en las municipalidades fue heterogénea como sigue: Santa Rita 87,56 por ciento, Mara 65,8 por ciento, Almirante Padilla 55,6 por ciento, Páez 32,9 por ciento y Miranda 7,8 por ciento. Se determinó una positividad del 51,8 por ciento en équidos no vacunados provenientes de los municipios Mara y Páez, con un incremento de la prevalencia (P<0,05) en el grupo nacido después de la última epidemia en 1995, y en el grupo sin información de edad. Estos hallazgos sugieren una inmunidad adquirida de forma natural en estos animales. No se encontraron diferencias en las prevalencias de acuerdo a género y especie. Los équidos del municipio Santa Rita mostraron un alto porcentaje de inmunidad para EEV, por lo contrario, un gran número de animales son susceptibles de adquirir la infección en el resto del municipalidades estudiadas. La prevalencia determinada sugiere fallas en la cobertura de vacunación, viabilidad de las vacunas utilizadas y en las estrategias programadas en las áreas en estudio. Estos esquemas deben ser evaluados para evitar un nuevo brote de EEV en esta zona

Melatonin increases interleukin-1beta and decreases tumor necrosis factor alpha in the brain of mice infected with the Venezuelan equine encephalomyelitis virus.

The effect of melatonin (MLT) on the brain levels of tumor necrosis factor alpha (TNF-alpha) and interleukin-1beta (IL-1beta) in Venezuelan equine encephalomyelitis (VEE) virus infection was determined. Brain homogenates from mice inoculated with 10 LD50 of VEE virus, untreated or treated with 500 microg MLT/kg body weight were assayed by ELISA to measure the levels of TNF-alpha and IL-1beta. MLT was injected daily starting 3 days before and continuing to 7 days after virus inoculation. Infected mice treated with MLT showed decreased levels of TNF-alpha when compared to the untreated infected mice on days 1, 3, 4, and 5 postinoculation (P < 0.001). In contrast, IL-1beta levels increased from days 1 to 5 in the infected mice treated with MLT when compared with the untreated infected animals (P < 0.01). The results suggest that the protective effect of MLT on the VEE virus infection could be due, among other factors, to a decrease in TNF-alpha synthesis along with an increase in the production of IL-1beta.

Melatonin induces changes to serum cytokines in mice infected with the Venezuelan equine encephalomyelitis virus.

We determined the influence of melatonin (MLT) on the induction of interleukin (IL)-2, IL-1 beta, IL-4, tumour necrosis factor-alpha (TNF-alpha) and gamma interferon (IFN-gamma) on mice infected with the Venezuelan equine encephalomyelitis (VEE) virus. Levels of IFN-gamma in the MLT-treated group were significantly increased (P < 0.001) when compared with the control non-infected group from day 1 to 6 post-infection (p.i.), while in infected mice treated with 500 micrograms MLT/kg of bodyweight enhanced levels of IFN-gamma were evident from 4 to 6 days p.i. No differences were detected in the levels of IL-2 between the controls, the infected mice treated with MLT and the infected untreated group, from day 2 p.i. No changes in serum levels of IL-4 were detected. In infected mice treated with MLT, blood levels of IL-1 beta were elevated almost 10-fold from day 1 to day 6 p.i. when compared to the control, the infected and the non-infected MLT-treated mice (P < 0.001). A highly significant rise (P < 0.001) of TNF-alpha was found in infected mice treated with MLT, from day 1 to 6 p.i. when compared to the other groups. A significant rise (P < 0.001) was also evident in the infected non-MLT-treated group and a less pronounced rise in the non-infected mice treated with MLT when compared to controls. The blockade of IFN-gamma and TNF-alpha did not inhibit the protective effect of MLT but when IL-1 beta was neutralized, 100% of the infected mice died suggesting that IL-1 beta induced by MLT treatment is a target cytokine to generate an immune response against the viral infection.