Relative reactivity of HIV-1 polyclonal plasma antibodies directed to V3 and MPER regions suggests immunodominance of V3 over MPER and dependence of high anti-V3 antibody titers on virus persistence
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Antibodies to two crucial regions, the third variable loop (V3) of gp120 and the membrane-proximal external region (MPER) of gp41 are important for HIV-1 neutralization. We here evaluated the relative binding of polyclonal plasma antibodies from 99 HIV-1-infected individuals from India to the consensus–C V3 and MPER peptides and observed immunodominance of V3 over MPER (p < 0.0001). We further examined the V3- and MPER-specific antibody correlates with clinical parameters. Our results revealed that anti-V3 antibody titers are significantly lower in patients on ART compared to drug-naive individuals (p < 0.0001), most likely due to a decrease in plasma viral load, irrespective of their CD4 counts and total IgG. No such association was observed for MPER, with a similar trend in four follow-up patients. These findings strongly suggest that high titers of V3-specific antibodies are dependent on persistence of virus in circulation, while antibodies to MPER are probably not.
We profoundly thank all the study participants. We acknowledge Prof. Miroslaw K. Gorny and Prof. Susan Zolla Pazner for their constant technical advice and support. We thank DBT (BT/PR 10511/MED/29/66/2008) and ICMR (61/7/2008-BMS) for funding this work. The AITRP fellowship (USA), JRF fellowship provided by ICMR is acknowledged.
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