qs-21 and Rotavirus-Infections

Virus-like particles (VLPs) composed of rotavirus VP2, VP6, and VP7 of G1 or G3 serotype specificity were produced in insect cells coinfected with recombinant baculoviruses expressing single rotavirus genes. The VLPs were purified and subsequently evaluated for immunogenicity and protection in the adult mouse model of rotavirus infection. Mice were vaccinated twice intramuscularly with G1 VLPs formulated with Quillaja saponaria (QS-21) or adsorbed to aluminium hydroxide (AlOH), or with G1 VLPs alone. G3 VLPs, G1 plus G3 VLPs, inactivated SA11 virions formulated with QS-21, or adjuvants were similarly inoculated as controls. Mice were examined for serum and fecal antibody responses by ELISA or microneutralization assays. Protective efficacy of the VLP vaccine formulations against oral challenge with the G3 murine ECwt rotavirus was assessed by comparing the antigen shed in stool of the VLP-vaccinated mice to that of the adjuvant-immunized mice. G1 VLPs in QS-21 induced significantly higher serum and intestinal antibody titers than G1 VLPs in AlOH or G1 VLPs alone. QS-21 also heightened serum and fecal antibody responses to G3 VLPs. These QS-21-augmented antibody responses were further characterized by equivalent IgG1 and IgG2a titers in sera, suggesting that G1 or G3 VLPs in QS-21 induced a balanced Th1/Th2 response. G1 VLPs in QS-21 induced partial protection (88%) against oral challenge with the heterotypic ECwt virus, whereas G3 VLPs in QS-21 induced complete protection (100%). In contrast, G1 VLPs when formulated with AlOH induced a predominant Th2 response and did not protect (1%) mice from virus challenge. Our results indicate that the type of adjuvant used clearly influences both antibody responses to rotavirus VLPs and the protective efficacy against rotavirus infections. These data have important implications for the development of parenteral vaccines to ameliorate rotavirus disease.

Topics: Adjuvants, Immunologic; Animals; Antibodies, Viral; Feces; Female; Mice; Mice, Inbred Strains; Rotavirus; Rotavirus Infections; Saponins; Th1 Cells; Th2 Cells; Vaccines, Synthetic; Viral Vaccines; Virion

I.m. immunization of mice with inactivated rotavirus particles protects against subsequent infection. To optimize protection, the effects of different adjuvants (QS-21, QS-7, QUIL A, PCPP and RAS) with potential for human use were compared. Twenty-eight days after i.m. immunization with 20 microg of purified, UV/psoralen-inactivated murine rotavirus (EDIM), either with or without adjuvant, BALB/c mice were orally challenged with live EDIM and virus shedding was measured. All five adjuvants stimulated large (P < 0.001) increases in rotavirus antibody, but significant differences were found between adjuvants. The order of rotavirus IgG responses, i.e. no adjuvant < RAS < QS-7 < Quil A < QS-21 < PCPP, was the same as the order of protection except that QS-21 and PCPP were reversed. These results establish the importance of adjuvants during i.m. immunization with rotavirus and identify those with the greatest potential.

Topics: Adjuvants, Immunologic; Animals; Antibodies, Viral; Female; Injections, Intramuscular; Mice; Mice, Inbred BALB C; Rotavirus; Rotavirus Infections; Saponins; Vaccines, Inactivated; Viral Vaccines

Based on studies in animal models, parenteral immunization has become recognized as a potential vaccination strategy against rotavirus. Using an adult mouse model, the effects of the saponin adjuvant QS-21 on protection against murine rotavirus (strain EDIM) infection was determined following two intramuscular (i.m.) immunizations with purified EDIM particles including triple-layered (tl) infectious particles, tl particles inactivated with psoralen/UV, and double-layered (dl) inactivated particles. All three particles stimulated large serum rotavirus IgG responses and small amounts of serum rotavirus IgA, but undetectable stool rotavirus IgA. Inclusion of QS-21 during immunization increased the serum responses approximately 2- to 10-fold and also stimulated low levels of stool rotavirus IgA. Protection based on reduced shedding of rotavirus following EDIM challenge was significant (P < 0.001) with each immunized group and was enhanced (P < 0.001) by inclusion of QS-21 during immunization. Mice immunized with either live or inactivated tl particles and QS-21 were almost fully protected. Furthermore, animals inoculated with dl particles and the adjuvant shed significantly (P = .02) less virus following challenge than mice immunized with inactivated tl particles even though the latter induced measurable titers of neutralizing antibody to EDIM. These results demonstrate significant protection against rotavirus following i.m. immunization with both dl and tl EDIM particles which is consistently enhanced with QS-21.

Topics: Adjuvants, Immunologic; Animals; Female; Immunity; Immunization; Injections, Intramuscular; Mice; Mice, Inbred BALB C; Rotavirus; Rotavirus Infections; Saponins; Virion

Virus-like particles (VLPs) are being evaluated as a candidate rotavirus vaccine. The immunogenicity and protective efficacy of different formulations of VLPs administered parenterally to rabbits were tested. Two doses of VLPs (2/6-, G3 2/6/7-, or P[2], G3 2/4/6/7-VLPs) or SA11 simian rotavirus in Freund's adjuvants, QS-21 (saponin adjuvant), or aluminum phosphate (AlP) were administered. Serological and mucosal immune responses were evaluated in all vaccinated and control rabbits before and after oral challenge with 10(3) 50% infective doses of live P[14], G3 ALA lapine rotavirus. All VLP- and SA11-vaccinated rabbits developed high levels of rotavirus-specific serum and intestinal immunoglobulin G (IgG) antibodies but not intestinal IgA antibodies. SA11 and 2/4/6/7-VLPs afforded similar but much higher mean levels of protection than 2/6/7- or 2/6-VLPs in QS-21. The presence of neutralizing antibodies to VP4 correlated (P < 0.001, r = 0.55; Pearson's correlation coefficient) with enhanced protection rates, suggesting that these antibodies are important for protection. Although the inclusion of VP4 resulted in higher mean protection levels, high levels of protection (87 to 100%) from infection were observed in individual rabbits immunized with 2/6/7- or 2/6-VLPs in Freund's adjuvants. Therefore, neither VP7 nor VP4 was absolutely required to achieve protection from infection in the rabbit model when Freund's adjuvant was used. Our results show that VLPs are immunogenic when administered parenterally to rabbits and that Freund's adjuvant is a better adjuvant than QS-21. The use of the rabbit model may help further our understanding of the critical rotavirus proteins needed to induce active protection. VLPs are a promising candidate for a parenterally administered subunit rotavirus vaccine.

Topics: Adjuvants, Immunologic; Aluminum Compounds; Animals; Antibodies, Viral; Disease Models, Animal; Feces; Female; Freund's Adjuvant; Haplorhini; Immunoglobulin A; Immunoglobulin G; Injections, Intramuscular; Intestines; Male; Phosphates; Rabbits; Rotavirus; Rotavirus Infections; Saponins; Vaccination; Vaccines, Synthetic; Viral Structural Proteins; Viral Vaccines