Characterization of African horsesickness virus serotype 4-induced polypeptides in Vero cells and their reactivity in Western immunoblotting.

The structural and non-structural proteins induced by African horsesickness virus serotype 4 (AHSV-4) in infected Vero cells were analysed by SDS-PAGE. Twenty-two virus-induced polypeptides were detected in infected cells by comparison with the polypeptides of mock-infected cells, of which four major (VP2, VP3, VP5 and VP7) and three minor (VP1, VP4 and VP6) structural proteins and four non-structural proteins (P58, P48, P21 and P20) were shown to be virus-coded, as deduced from electrophoretic and antigenic studies of purified virions and infected cells. The proteins that elicit the major antibody responses both in vaccinated and naturally or experimentally infected horses were shown to be three structural proteins, VP2, VP5 and VP7, and the four major non-structural proteins, P58, P48, P21 and P20, as deduced by radioimmunoprecipitation and immunoblotting assays. The cross-reactivity between AHSV-4 and sera obtained from horses experimentally infected with seven other serotypes was also determined. The results showed that VP5, VP7, P48, P21 and P20 are conserved and can be used to diagnose the infection of any of these eight serotypes.