Van Duyne, R. | Search bioRxiv

bioRxiv2024

HIV-1 controllers possess a unique CD8+ T-cell activation phenotype and loss of control is associated with increased expression of exhaustion markers

HIV-1 controllers are a rare population of individuals that exhibit spontaneous control of HIV-1 infection without antiretroviral therapy. These controllers can be categorized based on the level and mechanism of control. Understanding the mechanisms by which controllers maintain and eventually lose this ability would be highly valuable in HIV-1 cure or vaccine research. We explored whether CD8+ T cell exhaustion plays a role in the maintenance and loss of control by examining immune characteristics of HIV-1 controllers and controllers who lost control within the duration of the study. Previous work revealed the ability of CD8+ T-cells isolated from HIV-1 controllers to suppress HIV-1 replication in matched CD4+ T-cells ex vivo. Using flow cytometry, we analyzed exhaustion marker expression on CD8+ T-cells from these controllers and determined that they maintain a unique exhaustion profile as compared to HIV-negative individuals and standard progressors. The low level of T-cell exhaustion seen in controllers was reversed when these individuals lost control and showed increased viral loads. Immune checkpoint blockade targeting exhaustion markers was able to restore ex vivo control by CD8+ T-cells from former controllers. These results suggest that CD8+ T cell exhaustion compromises the ability to control viral replication in HIV-1 controllers. AUTHOR SUMMARYDespite the use of antiretroviral therapy, HIV continues to be a major public health issue that affects the lives of millions of people. Some infected people can control viral infection without therapy. The mechanism by which some people can control HIV infection at low, but detectable levels is unknown. In this study we examined the state of cytotoxic CD8+ T-cells in a group of HIV controllers and found that controllers maintain low levels of markers for a chronic state of activation called exhaustion. Loss of control correlated with increase in exhausted T-cells and for individuals who had recently lost control of infection we could restore protection in the cell culture dish by using immune checkpoint blockade drugs that affect exhaustion.

immunology↗

bioRxiv2020

Mechanistic Analysis of the Broad Antiretroviral Resistance Conferred by HIV-1 Envelope Glycoprotein Mutations

Despite the effectiveness of antiretroviral (ARV) therapy, virological failure can occur in some HIV-1 infected patients in the absence of mutations in the proteins targeted by these drugs. We previously reported that, in vitro, the lab-adapted NL4-3 strain of HIV-1 can acquire resistance to the integrase inhibitor dolutegravir (DTG) by acquiring mutations in the envelope glycoprotein (Env) that enhance the ability of HIV-1 to spread via cell-cell transmission. In this study, we investigated whether Env-mediated drug resistance extends to ARVs other than DTG and whether it occurs in other HIV-1 isolates. We demonstrate that Env mutations can broadly confer resistance to multiple classes of ARVs in the context of cell-cell but not cell-free infection and also increase resistance to ARVs when coupled with target-gene drug resistance mutations. To investigate the mechanism of Env-mediated drug resistance, we evaluated the impact of the Env mutations on Env stability and conformational dynamics. We observe that the NL4-3 Env mutants display a more stable and closed Env conformation compared to WT virus and reduced rates of gp120 shedding. We also selected for mutations in the gp41 ectodomain of clinically relevant, CCR5-tropic isolates in the presence of DTG. These Env mutants exhibit reduced susceptibility to DTG, with effects on replication kinetics and Env structure that are HIV-1 strain-dependent. Finally, to examine a possible in vivo relevance of Env-mediated drug resistance, we performed single-genome sequencing of plasma-derived virus from five patients failing an integrase inhibitor-containing regimen. This analysis revealed the presence of several mutations in the highly conserved gp120-gp41 interface despite low frequency of resistance mutations in integrase. These results suggest a "stepping-stone" model whereby mutations in Env that enhance the ability of HIV-1 to spread via a cell-cell route increase the opportunity for the virus to acquire high-level drug resistance mutations in ARV-target genes. Author summaryAlthough combination antiretroviral (ARV) therapy has proven highly effective in controlling the progression of HIV disease, drug resistance can be a major obstacle to long-term treatment, particularly in resource-limited settings. In most cases, resistance arises from the accumulation of mutations in the ARV-target genes; however, in some cases, resistance develops without ARV target-gene mutations. We previously reported that mutations in the HIV-1 envelope glycoprotein (Env) confer resistance to an integrase inhibitor. Here we investigated the mechanism of Env-mediated drug resistance and the possible contribution of Env to virological failure in vivo. We demonstrate that Env mutations can confer broad resistance to multiple classes of ARVs and define the effect of the Env mutations on Env subunit interactions and sensitivity to neutralizing antibodies. We also selected for drug resistance mutations in Env in clinically relevant HIV-1 isolates. We observed that many Env mutations accumulated in individuals failing integrase inhibitor therapy despite a low frequency of resistance mutations in integrase. Our findings suggest that broad-based, Env-mediated drug resistance may impact current and possibly future therapeutic strategies. Our findings also provide clues towards understanding how ARV-treated patients can experience virological failure without acquiring drug resistance mutations in ARV-target genes.

microbiology↗