Distribution of linear antigenic epitopes on GP120 encoded in sibling clones of novel New York HIV-1 subtype B isolates
Riley, J.P.; Pestano, G.A.; Harewood, K.; Alfred, L.J.; Guyden, J.; Boto, W.M.
Cellular and Molecular Biology 41(Suppl): S83-S91
1995
ISSN/ISBN: 0145-5680 PMID: 8574151 Document Number: 454781
We have initiated studies to characterize the predominant subtypes of HIV-1 which account for infections in a defined cohort of intravenous (IV) drug addicts. A region of ENV encoding the C2 to the V5 regions was amplified from the leukocytes of two subjects currently enrolled in a methadone maintenance program at the Addiction Research and Treatment Corporation (ARTC), in Brooklyn, New York. This region of the viral genome encodes the principal neutralizing determinant (PND) located in the V3 loop, the immunogenic CD4-binding site, and six other linear antigenic epitopes in the envelope glycoprotein, gp120. Phylogenetic tree analysis of the nucleotide sequences showed that the sibling clones RT1.4, RT1.15, RT1.17, RT1.21 and RT3.6, RT3.10, RT3.11, RT3.12 and RT3.15 derived from the isolates, RT1 and RT3, respectively, cluster with "group B" viruses at 99% confidence level. Marked intra-patient and inter-patient sequence variation was apparent in the V3 loop. The divergence included the presence of a previously unreported hexapeptide GPWGTF at the cap of the loop in the clones from RT1. The North American consensus hexapeptide, GPGRAF, was identified in the cap of the loop from the clones of RT3. Four of the five sibling clones from RT3 were closely related whereas the other clone, RT3.15, displayed five amino acid mutations downstream of the V3 cap. To assess the effect of sequence variation on the distribution of linear antigenic epitopes, complementary computer software programs, were used to analyze the gp 120 residues. Eight analogous antigenic epitopes were identified in the clones from both isolates despite the marked divergence in the primary sequences. The predicted PND in the RT3 clones showed the most extensive antigenic site so far documented for any isolate. A synthetic peptide comprising this epitope displayed extensive ELISA reactivity with the sera from asymptomatic New York donors. Mutations downstream of the cap in this epitope reduced antibody binding by gt 50%. Our findings demonstrate the potential relevance of genetic and serological analyses for the characterization of prevalent HIV-1 variants in high-risk communities. This approach may complement the current search for broadly reactive HIV-1 clones to facilitate vaccine development.