Immunogenicity and protective efficacy of a formalin-inactivated rotavirus vaccine combined with lipid adjuvants.

The immunogenicity and protective efficacy of inactivated rotavirus vaccine administered intramuscularly with lipid adjuvants; MPL (monophosphoryl lipid A from Salmonella minnesota) or L3 (monooleate/lauric acid) was evaluated in an infant mouse model. Purified and formalin-inactivated rhesus rotavirus (I-RRV) combined with one of the adjuvants were administered to female balb/c mice at 0, 4 and 8 weeks. High serum IgG antibody titers developed in all vaccinated groups; I-RRV (GMT 45524+/-9819), I-RRV-MPL (GMT 190637+/-64250) and I-RRV-L3 (GMT 126266+/-27553). The formalin-inactivation procedure preserved neutralizing epitopes and elicited high neutralizing antibody titers; I-RRV (GMT 43053 S.E.M.+/-4189), I-RRV-MPL (GMT 66398 S.E.M.+/-20202) and I-RRV-L3 (GMT 60887 S.E.M.+/-10750). All offsprings to immunized dams were protected against clinical diarrhea upon oral challenge with RRV. The IgG1/IgG2a ratio was in all immunized groups approximately 1 suggesting development of a balanced Th1/Th2 response.