Contaminación del suero fetal bovino con virus de la diarrea viral bovina / Contamination of bovine fetal serum with bovine viral diarrhea virus

Fetal bovine serum (FBS) used in cell culture may be contaminated with viruses, among them bovine viral diarrhea virus (BVDV) affecting the production of biological reagents and the results of diagnosis. The filtration process used in the preparation of commercial FBS abrogates most viral agents that may be present in raw FBS, but BVDV may pass through the filters because of its small size and its pleomorphism. While detection of bovine herpes virus-1 and parainfluenza-3 (PI-3) is determined by observation of the cytopathic effect, and also by hemadsorption in the case of PI-3, the most frequently isolated BVDV is non cytopathic, and infects cells without morphological alterations, inducing problems that arise after several cell generations. Batches of raw and processed FBS were analyzed. Frequencies of BVDV detection in raw serum in Argentina were similar to those published for USA. By conventional methods for BVDV detection, only 2 of 20 commercial batches of FBS had BVDV. Using cell cultures maintained with high concentrations of the serum under study for at least 2 weeks, with detection of viral antigen by indirect immunofluorescence, the percentage of BVDV detection was 80. This method shows that most lots of commercial FBS contain BVDV. RT-PCR allows faster detection of the viral genome, but it must be validated, as it does not show viral replication. To eliminate the problem of BVDV contamination in FBS, only gamma irradiated FBS is used in our laboratory.

Rinotraqueitis infecciosa bovina (VHB-1). II: Propiedades fisico-quimicas de la cepa L-114. / Infectious bovine rhinotracheitis (VHB-1). II.Physico-chemical properties of the L-114 strain

Se determino la estabilidad termica, densidad de flotacion y morfologia de la cepa L-114 de virus de la rinotraqueitis infecciosa bovina, aislada recientemente en el pais. La morfologia correspondio a un virus con envoltura, de 200 mm de diametro total y 90 mm de diametro del "core". La estructura de este ultimo fue de tipo icosaedrica, observandose particulas vacias y completas en la preparaciones purificadas de virus. A 37o C, cepa L-114 perdio mas del 90% de su infectividad en 15 hs. y a 56o C se inactivo muy rapidamente, perdiendo 3 log en 24 minutos. La densidad de flotacion en cloruro de cesio, luego de su concentracion por sedimentacion a traves de sacarosa al 47% (p/v), indica que el virus purificado tiene una densidad estimada de 1,25 g/ml, correspondiente a los virus herpes denominados livianos