RICH2 is implicated in viraemic control of HIV-1 in black South African individuals

Mechanism of Viral Suppression among HIV Elite Controllers and Long-Term Nonprogressors in Nigeria and South Africa

A subgroup among people living with HIV (PLHIV) experience viral suppression, sometimes to an undetectable level in the blood and/or are able to maintain a healthy CD4+ T-cell count without the influence of antiretroviral (ARV) therapy. One out of three hundred PLHIV fall into this category, and a large sample of this group can be found in areas with a high prevalence of HIV infection such as Nigeria and South Africa. Understanding the mechanism underpinning the nonprogressive phenotype in this subgroup may provide insights into the control of the global HIV epidemic. This work provides mechanisms of the elite control and nonprogressive phenotype among PLHIV in Nigeria and South Africa and identifies research gaps that will contribute to a better understanding on HIV controllers among PLHIV.

Lack of association of KIR2DL1-R245 and KIR2DL1-C245 with HIV-1 control in black South Africans with HLA-C2

Activating/inhibitory Killer-cell Immunoglobulin-like Receptors (KIRs) partly regulate Natural Killer (NK) cells. KIR2DL1 allotypes with cysteine at position-245 (KIR2DL1-C²⁴⁵) express at lower levels and demonstrate weaker inhibitory signaling compared to allotypes with arginine at position-245 (KIR2DL1-R²⁴⁵). The functional consequence of either allotype in infectious diseases is unknown. Since NK cells mediate antiviral immunity, we investigated KIR2DL1-R²⁴⁵ and KIR2DL1-C²⁴⁵ in association with HIV-1 virological control in untreated immunocompetent black South Africans. Allotype carriage, determined by KIR2DL1 sequencing, was similar between uninfected South Africans (n = 104) and other black African populations, but differed significantly from Europeans, while no significant differences were noted between uninfected and HIV-1-infected individuals (n = 52). KIR2DL1 expression, measured by flow cytometry, in uninfected individuals showed higher KIR2DL1-R²⁴⁵ expression compared to KIR2DL1-C²⁴⁵ in white donors (n = 27), while black donors (n = 21) generally expressed lower levels of both allotypes. KIR2DL1 expression was reduced in HLA-C2 carriers, most evident in black HLA-C2/C2 donors. KIR2DL1-R²⁴⁵ and KIR2DL1-C²⁴⁵ did not associate with viral load when HLA-C2 ligands were present, however in HLA-C1 homozygotes, individuals with only KIR2DL1-R²⁴⁵, showed lower viral loads compared to carriers of both allotypes. The lack of association of KIR2DL1-R²⁴⁵ or KIR2DL1-C²⁴⁵ with HIV-1 control in HLA-C2 carriers may relate to lower KIR2DL1 expression levels in a population with high HLA-C2 prevalence.

A high prevalence of potential HIV elite controllers identified over 30 years in Democratic Republic of Congo

Background

In-depth analysis of the HIV pandemic at its epicenter in the Congo basin has been hampered by 40 years of political unrest and lack of functional public health infrastructure. In recent surveillance studies (2017-18), we found that the prevalence of HIV in Kinshasa, Democratic Republic of Congo (11%) far exceeded previous estimates.

Methods

10,457 participants were screened in Kinshasa with rapid tests from 2017-2019. Individuals confirmed as reactive by the Abbott ARCHITECT HIV Ag/Ab Combo assay (n=1968) were measured by the Abbott RealTime HIV-1 viral load assay. Follow up characterization of samples was performed with alternate manufacturer viral load assays, qPCR for additional blood borne viruses, unbiased next generation sequencing, and HIV Western blotting.

Findings

Our data suggested the existence of a significant cohort (n=429) of HIV antibody positive/viral load negative individuals. We systematically eliminated collection site bias, sample integrity, and viral genetic diversity as alternative explanations for undetectable viral loads. Mass spectroscopy unexpectedly detected the presence of 3TC antiviral medication in approximately 60% of those tested (209/354), and negative Western blot results indicated false positive serology in 12% (49/404). From the remaining Western blot positives (n=53) and indeterminates (n=31) with reactive Combo and rapid test results, we estimate 2.7-4.3% of infections in DRC to be potential elite controllers. We also analyzed samples from the DRC collected in 1987 and 2001-03, when antiretroviral drugs were not available, and found similarly elevated trends.

Interpretation

Viral suppression to undetectable viral loads without therapy occurs infrequently in HIV-1 infected patients around the world. Mining of global data suggests a unique ability to control HIV infection arose early in central Africa and occurs in <1% of founder populations. Identification of this group of elite controllers presents a unique opportunity to study potentially novel genetic mechanisms of viral suppression.

Funding

Abbott Laboratories funded surveillance in DRC and subsequent research efforts. Additional funding was received from a MIZZOU Award from the University of Missouri. Research was supported in part by the Division of Intramural Research, National Institute of Allergy and Infectious Diseases, NIH.