Virological and antigenic characterization of two Peste des Petits Ruminants (PPR) vaccine viruses of Indian origin.

Virological and antigenic characteristics of two Indian Peste des Petits Ruminants (PPR) vaccine viruses namely "PPRV-Sungri/96" and "PPRV-AR/87" were investigated. This investigation included, type of cytopathic effect (CPE) produced, one-step growth curve, antigenic reactivity of viral antigens using a panel of 18 monoclonal antibodies (MAbs) and ability of viruses for neutralization using a monoclonal antibody directed to haemagglutinin (H) protein. Findings surprisingly indicated that the PPRV-AR/87 is a fast growing virus with an entirely different pattern of cytopathic effect in Vero cell system. This virus has a relatively short replication cycle of 21h with no clearly defined eclipse phase. Whereas, PPRV-Sungri/96 has a replication cycle of 72h with distinct eclipse phase. Both viruses showed very good antigenic correlation (r=0.823) based on reactivity with 18 MAbs in an indirect ELISA, indicating that they are closely antigenically related. PPRV-AR/87 showed a poor neutralization index with antihaemaglutinin MAb 4B11 and poor reactivity in sandwich ELISA using an anti-nucleocapsid (N) MAb as compared to PPRV-Sungri/96. The findings suggest that both these vaccine viruses can easily be differentiated based on the pattern of cytopathic effect and degree of neutralization using MAb 4B11.
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