Comparison of Rapid Centrifugation Assay with Conventional Tissue Culture Method for Isolation of Dengue 2 Virus in C6/36-HT Cells

A rapid centrifugation assay was compared with conventional tube cell culture for dengue virus isolation in both sera and autopsy samples from dengue and dengue hemorrhagic fever/dengue shock syndrome fatal cases. The rapid centrifugation assay allowed isolation of virus from 16.6% more samples than the conventional method, and it shortened the time for dengue virus detection. Finally, it allowed the isolation of dengue 2 virus in 42.8% of tissue samples from five fatal cases. Our results suggest that the rapid centrifugation assay may be useful for detection of dengue virus in clinical specimens

Comparison of Rapid Centrifugation Assay with Conventional Tissue Culture Method for Isolation of Dengue 2 Virus in C6/36-HT Cells

A rapid centrifugation assay was compared with conventional tube cell culture for dengue virus isolation in both sera and autopsy samples from dengue and dengue hemorrhagic fever/dengue shock syndrome fatal cases. The rapid centrifugation assay allowed isolation of virus from 16.6% more samples than the conventional method, and it shortened the time for dengue virus detection. Finally, it allowed the isolation of dengue 2 virus in 42.8% of tissue samples from five fatal cases. Our results suggest that the rapid centrifugation assay may be useful for detection of dengue virus in clinical specimens.</jats:p

Aplicación de la técnica de inmunoperoxidasa para la titulación de cepas del virus Dengue 1.

La aplicación de la técnica de inmunoperoxidasa para titular virus Dengue ha permitido eliminar algunas de las desventajas que presenta, para este mismo fin, la técnica de formación de placas en cultivos celulares, catalogada como un método fastidioso debido a los múltiples factores que influyen en la formación de las placas. En la literatura consultada se reporta la disminución del tiempo para la obtención de los resultados como la principal ventaja de la primera, pero no datos sobre su precisión. Teniendo esto en cuenta nos propusimos aplicar dicha técnica para titular virus Dengue 1. Se siguió el Procedimiento descrito para realizar la inmunoperoxidasa modificando el tiempo de fijación de las células infectadas de 5, 7 y 10 días y el bloqueo con TSF-Tween 20- SAB 1% durante una hora. La dilución de trabajo para el suero humano utilizado fue de 1/500 y para el líquido ascítico hiperinmune de ratón, contra Dengue 1 fue de 1/100; para los conjugados peroxidasa anti humano y anti ratón empleados, resultaron útiles diluciones de 1/100 y 1/200 para el primero y 1/500 y 1/1000 para el segundo. Se evidenciaron los focos de infección viral, al 7° y 10° días, pero no al 5º. Los títulos virales obtenidos por dos operadores presentaron un Coeficiente de Variación < 30%. Se seleccionó el 7º día para titular el virus, lográndose reducir el tiempo requerido para obtener los resultados con la técnica de placas. No hubo diferencias significativas entre los títulos virales calculados por ambas técnicas

First Epidemic of Echovirus 16 Meningitis in Cuba

From April to September 2000, an epidemic of aseptic meningitis spread throughout Cuba, with 16,943 reported cases. Virologic studies identified echovirus 16 as the cause of this epidemic. This is the first reported isolate of echovirus 16 from patients with viral meningitis in Cuba

Study of biologic attributes of cuban dengue 2 virus after serial passage in primary dog kidney cells

AbstractObjective: The serial passage of dengue viruses in primary dog kidney (PDK) cells has resulted in selection of attenuated viruses. However, the molecular changes responsible for loss of virulence are not well characterized. This article describes the isolation and biologic attributes of one dengue 2 virulent strain as a first step to allow the study of determinants of virulence at the molecular level.Methods: A15 dengue 2 Cuban strain was isolated from the viremic plasma of a patient with uncomplicated dengue fever during the 1981 epidemic. This was then subjected to serial passage in PDK cells. Viruses resulting from several PDK passages were compared to the parent strain for plaque size and temperature sensitivity, neurovirulence in newborn mice, and cytopathogenic effects on LLC-MK2 and C6/36-HT cell lines.Results: A15 dengue 2 Cuban strain was successfully propagated in PDK cells. Primary dog kidney 52 to 53 viruses exhibited several biologic attributes, such as small plaques, temperature sensitivity, reduced mouse neurovirulence, and cytopathic effect in permissive cell lines.Conclusions: These results represent the first step to allow attenuation of this strain of dengue 2 virus

Analysis of respiratory syncytial virus in clinical samples by reverse transcriptase-polymerase chain reaction restriction mapping

The aim of this study was to develop a polymerase chain reaction (PCR) for the detection of respiratory syncytial virus (RSV) genomes. The primers were designed from published sequences and selected from conserved regions of the genome encoding for the N protein of subgroups A and B of RSV. PCR was applied to 20 specimens from children admitted to the respiratory ward of "William Soler" Pediatric Hospital in Havana City with a clinical diagnosis of bronchiolitis. The PCR was compared with viral isolation and with an indirect immunofluorescence technique that employs monoclonal antibodies of subgroups A and B. Of 20 nasopharyngeal exudates, 10 were found positive by the three assayed methods. In only two cases, samples that yielded positive RNA-PCR were found negative by indirect immunofluorescence and cell culture. Considering viral isolation as the "gold standard" technique, RNA-PCR had 100% sensitivity and 80% specificity. RNA-PCR is a specific and sensitive technique for the detection of the RSV genome. Technical advantages are discussed