KINETICS OF VIRAL-RNA SYNTHESIS FOLLOWING CELL-TO-CELL TRANSMISSION OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1

The temporal appearance and levels of human immunodeficiency virus typ e 1 (HIV-1) fat, rev, nef, env and gag mRNA species were examined usin g a synchronized, one-step, cell-to-cell HIV-1 infection model involvi ng HUT-78 cells and HIV-1 persistently infected H3B cells, Individual mRNAs were quantified by RT-PCR using RNA standards transcribed in vit ro from cDNA clones, Consistent with an infection that produces high y ields of virus, significant levels of env and gag mRNAs were detected in the cytoplasm of infected cells late in the infection cycle, Howeve r, at no time after infection did levels of fat, rev and nef mRNA, whi ch encode the regulatory proteins of HIV-1, exceed their levels presen t in the persistently infected virus donor H3B cells, The absence of e arly phase induction of these mRNAs is in contrast to what is observed in cell-free HIV-1 infections or in PMA-stimulated HIV-1 chronically infected cell lines, Our results suggest that tat and rev mRNAs are al ready present in the cytoplasm of the persistently infected virus dono r cells at levels sufficient for initiation and establishment of a hig hly productive infection in HIV-1 fusion-mediated infected cells, Thus , lack of sufficient Tat and Rev proteins is not likely to be the limi ting factor for virus production in H3B cells, nor is increased produc tion of these proteins likely to be the cause of the increased virus p roduction seen following cell-to-cell transmission.