Serotyping International HIV-1 Isolates by V3 Peptides and Whole GP160 Proteins Using BIAcore

There are at present at least seven distinct genotypes of HIV-1 worldwide, with as much as 30% variation in DNA sequence between genotypes. Within each genotype family (clade) there is 15-20% diversity, whereas within a single HIV-1-infected individual there is intrapatient diversity as great as 5-10%. These quasispecies mutate over time within a given individual, potentially allowing for variants capable of evading immune surveillance. Serologic assays capable of identifying predominate genotypes that are present within particular geographic regions or that infect a particular individual may be crucial for the selection of optimal prophylactic or therapeutic HIV-1 vaccine candidates. We demonstrate that BIAcore measurements of HIV- 1 serum binding reactivity to peptides corresponding to the third hypervariable (V3) region of gp120 serologically distinguish the two predominate HIV-1 genotypes in Thailand. V3 sequences were determined through PCR amplification and DNA sequencing of HIV- 1 isolates from individuals infected with both HIV- 1 genotypes. Multiple peptides were synthesized and rapidly screened to select optimal peptides. Serotypes were also distinguished on the basis of BIAcore reactivity to whole recombinant HIV- 1 envelope glycoprotein (gp160) corresponding to genotypes B and E. In addition, preferential serum reactivity to genotype B or E gp 160 correlated with the ability of these sera to neutralize HIV-1 primary isolates of the homologous clade, indicating that the ability of serotyping is also predictive of immunotype.