Human immunodeficiency virus type 1 p24 antigen in cervicovaginal secretions

The failure to detect human immunodeficiency virus (HIV) antigen in cervicovaginal secretions (CVS) from HIV-infected women could be due in part to an in situ formation of immune complexes involving HIV antigens and cervicovaginal anti-HIV antibodies. CVS from 30 HIV-1-infected heterosexual women were assayed for p24 antigen detection by ELISA before and after acid disruption of immune complexes. Before acid treatment, free p24 antigen was detected in only 1 sample of CVS, whereas after acid dissociation, 4 (13.5%) of 30 samples had detectable and neutralizable p24 antigen. Adsorbent capacities of the CVS for recombinant p24 antigen, evaluated in an in vitro model, depended on both titer and avidity of cervicovaginal antibodies to HIV. In conclusion, local antibodies to HIV are able in vivo to bind HIV antigen within CVS and to participate in the immune exclusion of free virus particles or proteins.