Abstract:
Eight rhesus macaques were immunized intramuscularly four times (0, 1, 2, 4 months) with 0.5 mg or 0.1 mg of formalin inactivated whole SIV immunogen in the presence of muramyl dipeptide (MDP). After intravenous challenge with 50 MID50 of SIVmac251-32H, three of the four animals from the low dose group (plus the nonvaccinated control animals) became infected as demonstrated by reisolation of virus from PBMC, by SIVmac specific PCR, and by the development of a strong anamnestic response. All other animals (one from low dose group and all four of the high dose group) remained negative by all parameters at 4 months post challenge. At this time, three of these five protected animals again resisted challenge. There was no correlation between the levels of neutralizing antibody (nor anti-cell antibody) on the days of challenge and subsequent protection. The preliminary results from another ongoing experiment designed to identify the protective viral protein(s) in the immunogen will also be presented. Groups of four rhesus macaques were immunized with (i) whole inactivated SIVmac251-32H; (ii) virus depleted of the outer envelope glycoprotein by enzyme treatment; (iii) purified core particles devoid of the lipid bilayer (and hence transmembrane glycoprotein) or (iv) purified gag protein. To avoid the complication of possible anti-human cell immune responses a stock of SIVmac251-32H grown in rhesus PBMC and titrated in vivo was produced and used for challenge. In an initial trial, animals immunized with whole SIVmac in RIBI or envelope depleted virus in IFA became infected after challenge with 10 MID50 of this rhesus PBMC-grown virus. The four groups of monkeys, having been immunized three times, are being 'rested' for eight months before further boosting and challenge.
Keywords: Animal Antibodies, Viral/BLOOD Comparative Study Gene Products, gag/ADMINISTRATION & DOSAGE/IMMUNOLOGY/THERAPEUTIC USE Immunization Schedule Macaca mulatta Neutralization Tests Polymerase Chain Reaction Simian Acquired Immunodeficiency Syndrome/*IMMUNOLOGY/PREVENTION & CONTROL *SIV/GENETICS Vaccines, Inactivated/ADMINISTRATION & DOSAGE/*THERAPEUTIC USE Vaccines, Synthetic/ADMINISTRATION & DOSAGE/*THERAPEUTIC USE Viral Vaccines/ADMINISTRATION & DOSAGE/*THERAPEUTIC USE ABSTRACT 930630
M9361060
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