ISOTYPE-SPECIFIC ANTIBODY-RESPONSES TO ROTAVIRUS AND VIRUS PROTEINS IN COWS INOCULATED WITH SUBUNIT VACCINES COMPOSED OF RECOMBINANT SA11 ROTAVIRUS CORE-LIKE PARTICLES (CLP) OR VIRUS-LIKE PARTICLES (VLP)

The isotype antibody responses to bovine IND P-5, G6 and simian SA11 P -2, G3 rotavirus and SA11 rotavirus proteins (VP4, VP6 and VP7) in ser um, colostrum and milk were analysed by ELISA in three groups of vacci nated cows and nonvaccinated controls. Pregnant cows were vaccinated i ntramuscularly and intramammarily with recombinant baculovirus-express ed SA11 rotavirus VLP (triple-layered virus-like particles containing rotavirus VP2, VP4, VP6 and VP7), CLP (double-layered core-like partic les containing rotavirus VP2 and VP6); or inactivated SA11 rotavirus, respectively. Rotavirus antigen titers were highest (30-200-fold) in E LISA in the VLP vaccine compared to the inactivated SA11 vaccine. The IgG1, IgG2 and IgM geometric mean antibody titers (GMT) to rotavirus ( titers to bovine rotavirus vs SA11 rotavirus did not differ significan tly for any isotype or group) and the IgG2 GMT to VP6 in serum at calv ing in the vaccinated groups were significantly (P < 0.05) higher than in the control group. In colostrum, IgG1 and IgA rotavirus antibody t iters were significantly elevated for VLP (IgG1 GMT 832225, IgA GMT 16 384), CLP (IgG1 GMT 660561, IgA GMT 10321) and SA11 (IgG1 GMT 131072; IgA GMT 1448) vaccinated cows compared to control cows (IgG1 GMT 11585 , IgA GMT 45). The IgG1 and IgA GMT to rotavirus were significantly el evated (6-100-fold) in milk of VLP and CLP vaccinated cows compared to SA11 vaccinated or control cows. The isotype antibody responses to VP 6 in serum, colostrum and milk paralleled the responses to rotavirus, but titers were similar to 2-10-fold lower. Only cows vaccinated with VLP had significantly enhanced serum, colostral and milk antibody tite rs to rotavirus VP4 and VP7. These results demonstrate that rotavirus antibody titers in serum, colostrum and milk are significantly enhance d by use of non-infectious VLP, CLP and inactivated SA11 rotavirus vac cines, but the VLP or CLP vaccines induced the highest antibody respon ses, corresponding to their higher rotavirus antigen titers measured b y ELISA. Copyright (C) 1996 Elsevier Science Ltd.