RESISTANCE OF NEONATAL MONKEYS TO LIVE ATTENUATED VACCINE STRAINS OF SIMIAN IMMUNODEFICIENCY VIRUS

A major safety concern of using live-attenuated vaccine strategies aga inst AIDS is the potential exposure of neonates or fetuses to vaccine virus from the mother, Here we report that high viral loads and diseas e were observed in only 2 of 18 neonatal monkeys infected with gene-de leted vaccine strains of simian immunodeficiency virus. Pathogenicity was restricted to neonates born to unvaccinated mothers, that is, lack ing maternal immunity, and that received extremely high doses of vacci ne virus orally. No in utero transmission af vaccine virus was observe d in four neonates born to mothers vaccinated during the second trimes ter. Our results suggest that the live attenuated vaccine approach sho uld remain a viable option for preventing HIV infection and disease in high-risk human populations.