Project description:Human immunodeficiency virus type-2 (HIV-2) establishes reservoirs at levels comparable to HIV-1, but its infection is associated with lower rates of progression to AIDS. As such, a hallmark of people living with HIV-2 is the very low—usually undetectable—viral loads, which is partially explained by a post-transcriptional repression exerted at the level of protein synthesis and the accumulation of the full-length RNA in cytoplasmic granules. Here, we investigated whether HIV-2 Gag expression was regulated by the presence of the m6A RNA modification. Our results indicate that the HIV-2 full-length RNA contains m6A residues, which are required for Gag synthesis. Interestingly, the YTHDF family of cytoplasmic m6A readers exert different effects on HIV-2 Gag synthesis. As such, while YTHDF1 and YTHDF2 are necessary for Gag synthesis, YTHDF3 negatively regulates Gag expression by promoting full-length RNA localization in cytoplasmic granules. Interestingly, we demonstrate that the cellular m6A machinery including writers, erasers and readers re-localize into cytoplasmic granules together with the full-length RNA in a non-Gag producing cell sub-population. We also observed that FTO overexpression has no effect in Gag synthesis but promotes full-length RNA packaging suggesting a dynamic regulation of the cytoplasmic fate of this viral RNA. Together, these data suggest that the HIV-2 full-length RNA undergoes a complex regulation exerted by the cellular m6A machinery that controls the cytoplasmic localization, ribosome association and particle incorporation of this viral RNA.
Project description:Identifying immune correlates of protection is a major challenge in AIDS vaccine development. Anti-Envelope antibodies have been considered critical against SIV/HIV acquisition. Here, we evaluated the efficacy of a SHIV vaccine against SIVmac251 challenge, where the role of antibody was excluded as there was no cross-reactivity between SIV and SHIV Envelope antibodies. After eight low-dose rectal challenges with SIVmac251, 12 SHIV-vaccinated animals demonstrated 83% efficacy, compared to six naïve controls, suggesting protection could be achieved in the absence of anti-Envelope antibodies. Interestingly, CD8+ T cells (and some NK cells) were not essential for the preventing viral acquisition, as none of the CD8-depleted macaques were infected by SIVmac251 challenges. Initial investigation of protective innate immunity revealed that protected animals had elevated pathways related to platelet aggregation/activation, and reduced pathways related to interferon and responses to virus. Moreover, higher expression of platelet factor 4 (PF4) on circulating platelet-leukocyte aggregates was associated with reduced viral acquisition. Our data highlighted the importance of innate immunity and may provide new opportunities for novel HIV vaccines or therapeutic strategy development.
Project description:Guiding the humoral response against HIV-1 toward a MPER proximal region by immunization with a VLP-formulated antibody-selected envelope variant
Project description:Schlafen-5 (SLFN5) is an interferon-induced protein of the Schlafen family which are involved in immune responses and oncogenesis. To date, little is known regarding its anti-HIV-1 function. Here, the authors report that overexpression of SLFN5 inhibits HIV-1 replication and reduces viral mRNA levels, whereas depletion of endogenous SLFN5 promotes HIV-1 replication. Moreover, they show that SLFN5 markedly decreases the transcriptional activity of HIV-1 long terminal repeat (LTR) via binding to two sequences in the U5-R region, which consequently represses the recruitment of RNA polymerase Ⅱ to the transcription initiation site. Mutagenesis studies show the importance of nuclear localization and the N-terminal 1-570 amino acids fragment in the inhibition of HIV-1. Further mechanistic studies demonstrate that SLFN5 interacts with components of the PRC2 complex, G9a and Histone H3, thereby promoting H3K27me2 and H3K27me3 modification leading to silencing HIV-1 transcription. In concert with this, they find that SLFN5 blocks the activation of latent HIV-1. Altogether, their findings demonstrate that SLFN5 is a transcriptional repressor of HIV-1 through epigenetic modulation and a potential determinant of HIV-1 latency.
Project description:The mature HIV-1 envelope (Env) glycoprotein is composed of gp120, the exterior subunit, and gp41, the transmembrane subunit assembled as trimer by noncovalent interaction. There is a great body of literature to prove that gp120 binds to CD4 first, then to the co-receptor. We have recently demonstrated that gp120 cannot bind to the co-receptor without first interacting with CD4. Previous studies provided different glycomic maps for the HIV-1 gp120. Here, we build on previous work to report that the use of LC-MS/MS, in conjunction with hydrophilic interaction liquid chromatography (HILIC) enrichment to glycosylation sites, is associated with the assorted neutralizing or binding events of glycosylation targeted antibodies from different clades or strains. In this study, the microheterogeneity of the glycosylation from 4 different clades of gp120s is deeply investigated. Aberrant glycosylation patterns were detected on gp120 originated from different clades, viral sequences and host cells. The results of this study may help provide better understanding of the mechanism of how the glycans participate in antibody neutralizing process that target glycosylation sites.