CHARACTERIZATION OF THE FUNCTIONAL-PROPERTIES OF ENV GENES FROM LONG-TERM SURVIVORS OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 INFECTION

A small number of persons infected with human immunodeficiency virus t ype 1 (HIV-1) remain clinically and immunologically healthy for more t han a decade after infection, Recent reports suggest that these indivi duals may be infected with an attenuated strain of HIV-1; however, a c ommon genetic basis for viral attenuation has not been found in all ca ses. In the present study, we examined the functional properties of th e HIV-1 env genes from six long-term survivors, env clones were genera ted by PCR amplification of proviral env sequences, followed by clonin g of the amplified regions into expression vectors, Eight to ten clone s from each subject were screened by transient transfection for expres sion of the envelope precursor glycoprotein, gp160, Those clones expre ssing gp160 were then cotransfected with an HIV-1 luciferase reporter vector, pNL4-3Env(-)LUC(+) and evaluated for their ability to mediate infection of phytohemagglutinin-activated peripheral blood mononuclear cells in single cycle infectivity assays, Clones expressing gp160 wer e identified for all six long-term survivors, indicating the presence of proviral env genes with intact open reading frames. For two subject s, D and DH, the encoded envelope glycoproteins yielded high levels of luciferase activity when pseudotyped onto HIV-1 virions and tested in single cycle infectivity assays, In contrast, envelope glycoproteins cloned from four other long-term survivors were poorly processed and f ailed to mediate infection, Sequencing of the gp120/41 cleavage site a nd conserved gp41 cysteine residues of these clones did not reveal any obvious mutations to explain the functional defects, The functional a ctivity of env clones from long term survivors D and DH was comparable to that seen with several primary HIV-1 env genes cloned from individ uals,vith disease progression and AIDS, These results suggest that the long-term survival of subjects D and DH is not associated with overt functional defects in env; however, functional abnormalities in env ma y contribute to maintaining a long-term asymptomatic state in the othe r four cases we studied.