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Vaccine protection of rhesus macaques against simian immunodeficiency virus infection
J R Carlson1, T P McGraw, E Keddie
1Department of Pathology, School of Medicine, University of California, Davis 95616.
Abstract:
Rhesus macaques (Macaca mulatta) immunized with an inactivated whole SIVmac vaccine and muramyl dipeptide (MDP), incomplete Freund's adjuvant (IFA), or aqueous suspension were challenged intravenously with 0.1 TCID50 of cell-free SIVmac. Whereas virus was readily recovered from the peripheral blood lymphocytes of 10 of 10 nonvaccinated controls following this challenge dose, virus was not recovered from the three animals that received the vaccine with MDP nor from one of two animals that received the vaccine with IFA and one of three animals that received the aqueous vaccine. The animals that were protected against challenge were those that had detectable SIV antibody response to the envelop, both the outer glycoprotein (gp120) and the truncated transmembrane glycoprotein (gp31). Protected monkeys tended to have higher titers of syncytial inhibition antibody prior to challenge. An anamnestic response after challenge was observed only in the vaccinated monkeys that became infected. Vaccinated animals that became challenge-infected tended to live longer than infected controls. These results confirm those at two other primate centers and indicate that killed whole SIV vaccines can protect against low challenge doses of SIV and prevent early death in those monkeys that do become infected. The mechanism of this protection remains undetermined. This finding adds optimism to the possibility of an eventual AIDS vaccine.
Insights
Inactivated whole SIV vaccines with muramyl dipeptide (MDP) or incomplete Freund's adjuvant (IFA) protected rhesus macaques against simian immunodeficiency virus (SIV) challenge. Vaccinated macaques that became infected lived longer, offering optimism for AIDS vaccine development.
Area of Science:
- Veterinary Immunology
- Virology
- Vaccinology
Background:
- Simian immunodeficiency virus (SIV) infection in rhesus macaques serves as a model for human immunodeficiency virus (HIV) research.
- Developing effective vaccines against SIV is crucial for advancing AIDS vaccine development.
Purpose of the Study:
- To evaluate the efficacy of an inactivated whole SIVmac vaccine when combined with different adjuvants.
- To assess the protective effects of the vaccine against intravenous SIVmac challenge in rhesus macaques.
Main Methods:
- Rhesus macaques were immunized with an inactivated whole SIVmac vaccine combined with muramyl dipeptide (MDP), incomplete Freund's adjuvant (IFA), or an aqueous suspension.
- Vaccinated and control groups were challenged intravenously with cell-free SIVmac.
- Viral recovery from peripheral blood lymphocytes and antibody responses were monitored.
Main Results:
- Vaccination with SIVmac and MDP or IFA provided protection against SIV challenge, with no virus recovered from vaccinated macaques in some groups.
- Protected animals exhibited detectable SIV antibody responses to envelope glycoproteins (gp120 and gp31).
- Vaccinated animals that became infected post-challenge lived longer than infected controls.
Conclusions:
- Killed whole SIV vaccines can confer protection against low-dose SIV challenge and delay mortality in infected macaques.
- The findings support the potential of SIV vaccines as a step towards an AIDS vaccine.
- The precise mechanism of protection warrants further investigation.