ROTAVIRUS SUBUNIT VACCINES

We evaluated rotavirus subunit vaccines for use in humans and animals. Insect cells were co-infected with combinations of individual baculov irus recombinants expressing human, bovine or simian rotavirus VP2, VP 4, VP6 or VP7 to produce virus-like particles (VLPs). To determine whe ther immunization with VLPs could induce active protective immunity, V LPs were administered parenterally to rabbits, and the immune response and protection from rabbit ALA rotavirus challenge were evaluated. Co mplete or partial protection was attained, showing that parenteral imm unization with VLPs induces active protective immunity. We also examin ed whether heterotypic immune responses could be induced with a limite d number of broadly reactive VP7 proteins or with chimeric particles ( multiple VP7 types on individual particles). The feasibility of this a pproach was determined by immunizing mice with VLPs containing a G3 VP 7 or G1 VP7 and chimeric G1/G3 VLPs. Broadly reactive neutralizing ant ibody was induced by the G1 VLPs. VLPs also have been successfully use d to boost lactogenic (colostral and milk) immunity in dairy cows. Tak en together, these results show that VLPs can be effective immunogens in rabbits, mice and dairy cattle when administered parenterally, a li mited number of VLPs may be sufficient to produce a broadly protective vaccine, and G3 VLPs may serve as an effective subunit vaccine for us e in bovines.