RELATION BETWEEN CHANGES IN CELLULAR LOAD, EVOLUTION OF VIRAL PHENOTYPE, AND THE CLONAL COMPOSITION OF VIRUS POPULATIONS IN THE COURSE OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 INFECTION

The relationship between the evolution of human immunodeficiency virus type 1 (HIV-1) biologic phenotype, changes in the proportion of infec ted peripheral blood mononuclear cells, and the relative contribution of non-syncytium-inducing (NSI) and syncytium-inducing (SI) HIV-1 vari ants to virus load was studied during the course of HIV-1 infection. I n 65 HIV-1-infected subjects, the proportion of infected CD4 T cells w as higher in persons who carried SI variants. Longitudinal studies rev ealed that the emergence of SI HIV-1 variants can occur at relatively low numbers of HIV-1-infected cells, Emergence of SI variants frequent ly coincided with an increase of virus load due to an expansion of bot h NSI and SI variants, although the contribution of SI viruses to the total virus population significantly increased with time after SI phen otype conversion. These data indicate that NSI to SI phenotype convers ion, rather than resulting from high virus load, is part of the sequen ce of events that leads to increased virus load and CD4 cell depletion .