HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 ENV AND P17(GAG) SEQUENCE VARIATION IN POLYMERASE CHAIN REACTION-POSITIVE, SERONEGATIVE INJECTION-DRUG USERS

Variation in gene sequences from human immunodeficiency virus type 1 ( HIV-1) p17(gag) and the third hypervariable region (V3 loop) of env wa s examined in a cross-sectional study of single specimens from 4 HIV-1 polymerase chain reaction-positive, seronegative injection drug users . As observed in sexually transmitted disease, clones of HIV-1 genes i solated from an individual were remarkably homogeneous, with amino aci d variation in the envelope region of 0.3%-0.9% and in p17(gag) of 0.0 %-0.7%. Intersubject variation was much greater (at the amino acid lev el, 15% for the envelope and 4.3% for p17(gag)), with conservation in the envelope only of regions at the base of the V3 loop. Since at leas t some subjects likely acquired infection intravenously, the ability o f virus to survive in seminal fluid or on mucosal surfaces cannot expl ain the observed homogeneity, which may depend on direct interactions between the virus and the infected cell.