J Virol. 2000 April; 74(8): 3537à3542.

Evidence for Recombination of Live, Attenuated Immunodeficiency Virus Vaccine with Challenge Virus to a More Virulent Strain

Bjšrn R. Gundlach et al

Live, attenuated immunodeficiency virus vaccines, such as nef deletion mutants, are the most effective vaccines tested in the simian immunodeficiency virus (SIV) macaque model. In two independent studies designed to determine the breadth of protection induced by live, attenuated SIV vaccines, we noticed that three of the vaccinated macaques developed higher set point viral load levels than unvaccinated control monkeys. Two of these vaccinated monkeys developed AIDS, while the control monkeys infected in parallel remained asymptomatic. Concomitant with an increase in viral load, a recombinant of the vaccine virus and the challenge virus could be detected. Therefore, the emergence of more-virulent recombinants of live, attenuated immunodeficiency viruses and less-aggressive wild-type viruses seems to be an additional risk of live, attenuated immunodeficiency virus vaccines.

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Although humans are usually exposed to pathogenic viruses, recombinants between a host-adapted vaccine strain and a pathogenic virus might lead to more rapid progression to disease. In addition, the emergence of new variants might be favored

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