LIMITED SEQUENCE HETEROGENEITY AMONG BIOLOGICALLY DISTINCT HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 ISOLATES FROM INDIVIDUALS INVOLVED IN A CLUSTERED INFECTIOUS OUTBREAK

Human immunodeficiency virus type 1 isolates were obtained over a 3-year period from blood, brain, and lung of three patients in a clustered infectious outbreak. This included a blood donor who was initially asymptomatic but subsequently developed AIDS-related complex and two neonatal transfusion recipients who developed AIDS. Isolates from brain and lung replicated to > 30-fold higher levels in primary monocyte cultures than did those from blood; no growth differences on primary lymphocytes were observed. Thirteen clones were obtained from seven isolates, and env sequences were determined. The predicted amino acid sequences among these clones differed by only 0.01% but differed by 15-27% when compared to previously sequenced isolates from other patients. The level of envelope amino acid sequence divergence noted among these isolates is considerably lower than that previously reported for other human immunodeficiency virus isolates. No differences in the envelope unique to lung or brain isolates compared to blood isolates were noted. This study provides evidence that mutations in the envelope may not be necessary for disease progression and that other portions of the viral genome may contribute to cell-specific tropism.