Abstract

PIP: The genetic polymorphism of the human immunodeficiency virus (HIV) has been established. In addition to the nucleic acid variations responsible for the restriction map polymorphism, isolates of HIV differ significantly at the protein level, especially in the envelope, in terms of amino acid substitutions and reciprocal insertions-deletions. In this investigation, molecular cloning and nucleotide sequencing of the genomes of 2 HIV isolates obtained from patients in Zaire were carried out. The 1st isolate was recovered in 1983 from a 24-year-old woman with acquired immunodeficiency syndrome (AIDS); the 2nd was isolated in 1985 from a 7-year-old boy with AIDS-related complex (ARC). The genetic organization of these isolates was identical to that found in other HIV isolates from the US and Europe, particularly in terms of the conservation of the central region located between the pol and env genes composed of a series of overlapping open reading frames. There were, however, substantial differences in the primary structure of the viral proteins, with env being more variable than the gag and pol genes. Alignment of the envelopes revealed hypervariable domains with a great number of mutations and reciprocal insertions and deletions. Overall, this analysis suggests that the African and American HIV infections have a common origin given their identical genetic organization. The sequence variability reflects a divergent evolutionary process, and the fact that the 2 Zairian isolates were more divergent than American isolates studied by others indicates a longer evolution of HIV in Africa. An essential research goal is to identify the HIV envelope domains responsible for the virus-cellular surface antigen interaction since an immune response against these epitopes could elicit neutralizing antibodies for use in a vaccine.