Analysis of Nef,Gag-specific CTL responses in HIV-1 highly exposed persistently serongeative individuals
Objective To study the characteristics of HIV-1 Nef,Gag-specific cytotaxic T lymphocyte (CTL)responses in Chinese HIV-1 highly exposed persistently seronegative(HEPS)individuals and to evaluate the roles of the specific responses in persistent nontransmission of HIV-1.Methods HIV-1 specific CTL responses to 14 overlapping poptide pools encompassing products of the HIV-1 gag and nef genome were teated by INF-γenz- yme-linked immunospot(ELISPOT)assay in 10 HEPS individuals from discordant couples,12 HIV/AIDS patients (by sexual transmission)and 4 healthy subjects without any exposure.The recognition rates,average magnitude and breadth of the specific responses were compared among the three cohorts.Results It was confirmed that Gag and Nef-specific T lymphocytes were present in HEPS individuals,which were absent in healthy control.However, the responses were much less frequent(50% vs 100%),of a lower magnitude(4.3%),and of narrower breadth (37.7%)than in HIV/AIDS patients.Main peptides recognized by HEPS individuals were less frequently recog- nized by HIV/AIDS patients.Conclusion Differences exist in the characteristics of Nef,Gag-specific responses between HEPS individuals and HIV/AIDS patients.CTL responses may play a key role in the protection from HIV-1 infection in HEPS individuals.