Immunogenicity, antigenicity, and protection efficacy of baculovirus expressed VP4 trypsin cleavage products, VP5(1)* and VP8* from rhesus rotavirus.

Rhesus rotavirus (RRV) VP4 trypsin cleavage product VP5(1), a truncated form of VP5, was expressed in baculovirus and found by immunoprecipitation to be antigenically similar to VP5* on the virion. Immunization of mice with VP5(1)* elicited neutralizing antibody that was found to be cross-reactive with viruses representing P genotypes 1, 3, 4, 6, 7, and 8. Baculovirus expressed trypsin cleavage products, VP8* (amino acids 1-246) and VP5(1)* (amino acids 247-474), were tested for their ability to elicit a protective response in a murine model of passive protection. These results were compared to those obtained with baculovirus expressed RRV VP4. Dams immunized with baculovirus expressed RRV VP4 gave birth to pups protected from RRV virus challenge. Neither VP5(1)* nor VP8* was as effective at generating protective immunity as full length VP4. However, antibody to VP5(1)* was more effective than antibody to VP8* at mediating protection even though the neutralizing antibody titers as measured by hemagglutination inhibition and focus reduction neutralization were similar.