Peptide serology for analysis of the inter- and intra-individual variation in the HIV-1 V3 domain.

Objective: To investigate whether the specificity of antibody responses to the gp120 V3 domain in HIV-1-infected individuals is related to the variability of this region.

Methods: Sera from a cohort of 22 HIV-1-infected Ugandans were tested against peptides derived from each individual's autologous proviral V3 apex sequence. Autologous peptide reactivity was compared with reactivity to peptides derived from two Ugandan consensus sequences and previously isolated US/European and African viruses. Peptides from individuals with heterogeneous V3 apex sequences, representing different HIV-1 variants, were obtained and tested against the corresponding sera.

Results: A notable cross-reactivity to different V3 apex peptides was observed. However, in the majority of sera, antibody reactivity to the autologous peptides was found to exceed reactivity to any of the other peptides tested. V3 proviral sequences from the Ugandan cohort studied have been shown to be closely related to the HIV-1MN isolate and thus, their sera gave better reactivity to V3MN and related peptides than to peptides representing other African HIV-1 isolates. In individuals with heterogeneous V3 proviral sequences, we could distinguish divergent antibody responses to the genomic variants differing by single amino acids.

Conclusion: Analysis of seroreactivity to peptides might constitute a relevant tool for investigating the variability of the HIV-1 gp120 V3 domain within infected populations and single individuals.