Background Fc gamma receptors (FcγR) are cell surface glycoproteins that bind to the Fc portions of immunoglobulin IgG antibodies to elicit diverse effector functions. Polymorphisms in different FcγR genes have been associated with HIV infection and vaccine trial outcomes. Some studies have suggested that FcγRIIa may be a marker of latent reservoir size, however, this remains controversial. Hence whether FcγRIIa and other Fc receptors have functional consequences on the size or reactivation capacity of the reservoir needs to be investigated.

Methods In this pilot study, single-nucleotide polymorphisms (SNPs) in FcγRIIIa, FcγRIIa, and FcγRIIb genes were determined by Sanger sequencing in 50 HIV-infected ART-suppressed individuals. HIV reservoir size was determined by quantifying total HIV DNA (vDNA) and cell-associated unspliced (US) HIV RNA by qPCR. Association analysis was performed using three coding SNPs, one per gene (FcγRIIIa-rs396991, FcγRIIa-rs1801274, and FcγRIIb-rs1050501).

Results The median reservoir size as estimated by vDNA copy number was 116 (range, 1 - 5798) copies/million cells and US RNA was detectable in 15 out of the 50 samples. Our analysis found the median reservoir size was almost 3 times larger in males compared to females who are suppressed (p=0.038).

Conclusion Reservoir size was observed to be larger in younger patients compared to those older, however, not statistically significant. However, there was no significant associations between the FcγR SNPs and HIV vDNA or US RNA. Studies in larger cohorts are necessary to explore associations between FcγR polymorphisms and HIV reservoir.

Funding: EDCTP-AREF TMA2018PF-2535