Solis-Leal, A. | Search bioRxiv

bioRxiv2023

Lymphoid tissues contribute to viral clonotypes present in plasma at early post-ATI in SIV-infected rhesus macaques

The rebound-competent viral reservoir (RCVR), comprised of virus that is able to persist during antiretroviral therapy (ART) and mediate reactivation of systemic viral replication and rebound viremia after antiretroviral therapy interruption (ATI), remains the biggest obstacle to the eradication of HIV infection. A better understanding of the cellular and tissue origins and the dynamics of viral populations that initiate rebound upon ATI could help develop targeted therapeutic strategies for reducing the RCVR. In this study, barcoded SIVmac239M was used to infect rhesus macaques to enable monitoring of viral barcode clonotypes contributing to virus detectable in plasma after ATI. Blood, lymphoid tissues (LTs, spleen, mesenteric and inguinal lymph nodes), and non-lymphoid tissues (NLTs, colon, ileum, lung, liver, and brain) were analyzed using viral barcode sequencing, intact proviral DNA assay, single-cell RNA sequencing, and combined CODEX/RNAscope/in situ hybridization. Four of seven animals had viral barcodes detectable by deep sequencing of plasma at necropsy although plasma viral RNA remained < 22 copies/mL. Among the tissues studied, mesenteric and inguinal lymph nodes, and spleen contained viral barcodes detected in plasma, and trended to have higher cell-associated viral loads, higher intact provirus levels, and greater diversity of viral barcodes. CD4+ T cells were the main cell type harboring viral RNA (vRNA) after ATI. Further, T cell zones in LTs showed higher vRNA levels than B cell zones for most animals. These findings are consistent with LTs contributing to virus present in plasma early after ATI. One Sentence SummaryThe reemerging of SIV clonotypes at early post-ATI are likely from the secondary lymphoid tissues.

immunology↗

bioRxiv2020

Vpr R36W and R77Q Mutations Alter HIV-1 Replication and Cytotoxicity in T Lymphocytes

Chronic immune inflammation (CII) is a characteristic symptom of HIV-1 infection that contributes to acquired immunodeficiency syndrome (AIDS) progression in infected patients. Distinct AIDS development rates have shown that there are Rapid Progressor (RP) and Long-Term Non-Progressor (LTNP) patients, but the circumstances governing these differences in disease progression are poorly understood. Mutations in the Viral Protein R (Vpr) have been suggested to have a direct impact on disease progression. Studies have shown that Vpr interacts with both host and viral factors; these interactions affect cellular activities such as cell cycle progression and enhancement of apoptosis. The Vpr mutants R36W and R77Q have been associated with RP and LTNP phenotypes, respectively; however, these findings are still controversial. This study sheds light on the effects that Vpr mutations have in the context of HIV-1 infection of the HUT78 T cell line, using replication-competent CXCR4-tropic virus strains. Our results show a replication enhancement of the R36W mutant (increased viral load and percentage of p24+ cells) accompanied by increased cytotoxicity. Interestingly, the R77Q mutant showed a unique enhancement of apoptosis (measured by Annexin V and TUNEL staining) and G2 cell cycle arrest; these effects were not seen with WT or R36W viruses. Since necrosis is associated with the release of pro-inflammatory factors, the R36 mutation could lead to more robust CII and the RP phenotype. Conversely, the R77Q mutation leads to apoptosis, potentially avoiding CII and leading to a LTNP phenotype. Thus, Vpr mutations may impact HIV-1 related progression to AIDS. ImportanceThe vpr gene is thought to be an important virulence factor in Human Immunodeficiency Virus type 1 (HIV-1). vpr polymorphisms have been associated with different rates of acquired immunodeficiency syndrome (AIDS) progression. However, there is controversy about the cytopathic and virulence phenotypes of Vpr mutants, with contradictory conclusions about the same mutants. Here, we examine the replication capacity, apoptosis induction, and G2 cell cycle arrest phenotypes of three vpr mutants compared to wild-type HIV-1. One mutant associated with rapid AIDS progression replicated more efficiently and killed cells more rapidly than wild-type HIV-1. Another mutant associated with slow AIDS progression triggered apoptosis more efficiently than wild-type HIV-1. These results shed additional light on the role of vpr polymorphisms in T cell killing by HIV-1 and may help to explain the role of Vpr in different rates of AIDS progression.

microbiology↗