A formalin inactivated whole SIV_mac vaccine in Ribi adjuvant protects against homologous and heterologous SIV challenge

Abstract

Eight monkeys were immunized at 0, 4, 9, and 18 weeks with a total of 2 mg of formalin inactivated SIVmac vaccine with Ribi adjuvant. Two weeks after the last booster four immunized monkeys and two controls were challenged with 10 MID50 of live homologous virus SIVmac, and the remaining four vaccinated animals along with two controls were challenged with the heterologous SIVsm strain. All eight vaccinated monkeys resisted the virus challenge, whereas all controls became infected. Three months after the first challenge the monkeys were rechallenged with the same virus strain, without further boosting. Two of four vaccinated monkeys were still resistant to the homologous SIV strain, and three of four monkeys were resistant to the heterologous SIVsm strain. This study demonstrates vaccine induced cross‐protection between SIV strains.

Strategies for AIDS vaccines

“…These results were confirmed and extended by Murphey-Corb et al (1989) who showed that most animals immunized with formalin-inactivated vims were protected against infection with SIV. Similar results were subsequently obtained by several laboratories using virus-infected cells (Stott et al, 1990) or partially purified virus, inactivated by aldehydes (Putkonen et al, 1991(Putkonen et al, , 1992Johnson et al, 1992a;Le Grand et al, 1992), 0-propiolactone (Stott et al, 1990), detergent (Osterhaus et al, 1992) or psoralin and UV light (Carlson et al, 1990). Several different isolates of SIV or infectious molecular clones derived from them were used to prepare the vaccine and challenge viruses.…”