Adaptation and Comparative Growth Behaviour of Egyptian SPV isolates in Vero

Abstract

Although primary lamb testis (LT) cell culture seemed to be sensitive and the most suitable for adaptation of recently isolated sheep poxvirus (SPV), giving rapid and complete Cytopathic Effect (CPE), these cells were difficult to be maintained as a monolayer cell line. Moreover, their primary and secondary cultures still have many of the detrimental, inherent characteristics and contaminating elements. Therefore, the use of more stable cell lines (Vero cells) becomes a necessity for an economic preparation of SPV seed vaccine. Three SPV isolates, which previously passaged and adapted in lamb testis cell culture (isolates with titer reaching to 6.5 Log10 TCID50 / ml), were chosen to be transferred and propagated on Vero cell line. With further studies on its growth curve and growth kinetics to identify the growth behavior of these isolates, followed by detection of the virus antigen in the infected Vero cells by indirect florescent antibody technique (IFAT) as the first step for antigenic identification of the isolated adapted virus. The chosen optimum multiplicity of infection (MOI) was (0.01) with the optimum virus harvestation time was 4 days post-inoculation (DPI) and virus titre was equal to 10 5.5 . Finally, we recommend the use of Vero cells as a continuous cell line for preparation of seed of SPV prepared from an Egyptian isolate.