Further studies of salivary inhibition of HIV-1 infectivity.

An HIV-1/ATH8-cell cytopathic system was used to characterize the previously reported anti-HIV-1 activity of human saliva. Inhibitory activity was demonstrated by monitoring viable cell counts, HIV-1 p24 core antigen, and reverse transcriptase levels. Nonfiltered whole saliva, sterilized by irradiation, protected the ATH8 cells from HIV-1 infection. When HIV-1/saliva mixtures were filtered following incubation, the quantity of virus was significantly less (approximately 50%) than in HIV-1/media-filtered controls, suggesting that salivary aggregation and/or agglutination may be involved in the inhibitory activity. However, a sufficient number of apparently morphologically intact viral particles were still present in the HIV-1/saliva filtrates to lead to infection. When saliva was filtered prior to incubation with HIV-1, these filtrates showed substantial inhibitory activity, although reduced compared with that of non-prefiltered saliva. We conclude that saliva likely has several means by which to inhibit HIV-1 infectivity.