Gamma-delta (γδ) T cells recognize antigens in a major histocompatibility complex (MHC) independent and have cytotoxic capability. Human immunodeficiency virus (HIV) infection reduces the proportion of the Vδ2 cell subset compared to the Vδ1 cell subset of γδ T cells in the blood in most infected individuals, except for elite controllers. The capacity of Vδ2 T cells to kill HIV-infected targets has been demonstrated in vitro, albeit in vivo confirmatory studies are lacking. Here, we provide the first characterization of γδ T cell-HIV interactions in bone marrow-liver-thymus (BLT) humanized mice and examined the immunotherapeutic potential of Vδ2 T cells in controlling HIV replication in vivo. We demonstrate a reduced proportion of Vδ2 T cells and an increased proportion of Vδ1 T cells in HIV-infected BLT humanized mice, like in HIV-positive individuals. HIV infection in BLT humanized mice also impaired the ex vivo expansion of Vδ2 T cells, like in HIV-positive individuals. Adoptive transfer of activated Vδ2 T cells did not control HIV replication during cell-associated HIV transmission in BLT humanized mice but instead exacerbated viremia, suggesting that Vδ2 T cells may serve as early targets for HIV replication. Our findings demonstrate that BLT humanized mice can model γδ T cell-HIV interactions in vivo.
Copyright © 2022 Biradar, Agarwal, Lotze, Bility and Mailliard.

HIV-1 Nef is an attractive target for antiretroviral drug discovery because of its role in promoting HIV-1 infectivity, replication, and host immune system avoidance. Here, we applied a screening strategy in which recombinant HIV-1 Nef protein was coupled to activation of the Src-family tyrosine kinase Hck, which enhances the HIV-1 life cycle in macrophages. Nef stimulates recombinant Hck activity in vitro, providing a robust assay for chemical library screening. High-throughput screening of more than 730 000 compounds using the Nef·Hck assay identified six unique hit compounds that bound directly to recombinant Nef by surface plasmon resonance (SPR) in vitro and inhibited HIV-1 replication in primary macrophages in the 0.04 to 5 μM range without cytotoxicity. Eighty-four analogs were synthesized around an isothiazolone scaffold from this series, many of which bound to recombinant Nef and inhibited HIV-1 infectivity in the low to submicromolar range. Compounds in this series restored MHC-I to the surface of HIV-infected primary cells and disrupted a recombinant protein complex of Nef with the C-terminal tail of MHC-I and the μ1 subunit of the AP-1 endocytic trafficking protein. Nef inhibitors in this class have the potential to block HIV-1 replication in myeloid cells and trigger recognition of HIV-infected cells by the adaptive immune system in vivo.

h4>Background: /h4> Loss of function mutations in the human immunodeficiency virus (HIV) negative factor ( nef ) gene are associated with reduced viremia, robust T cell immune responses, and delayed acquired immunodeficiency syndrome (AIDS) progression in humans. Importantly, Nef persists in antiretroviral therapy-treated chronic HIV-infected individuals. In vitro studies have shown that mutations in the Nef dimerization interface significantly attenuate viral replication and impair host defense. However, in vivo, mechanistic studies on the role of Nef dimerization in HIV infection are lacking. Humanized rodents with human immune cells are robust platforms for investigating the interactions between HIV and the human immune system. The bone marrow-liver-thymus-spleen (BLTS) humanized mouse model carries human immune cells and lymphoid tissues that facilitate anti-viral immune responses. h4>Results: /h4> Here, we demonstrate that nef deletion abrogates HIV viremia and HIV-induced immune dysregulation in the BLTS-humanized mouse model. Furthermore, we demonstrate that preventing Nef dimerization abrogates HIV viremia and HIV-induced immune dysregulation in the BLTS-humanized mouse model. We also demonstrate that viremic control of HIV carrying deletion or dimerization defects in nef is associated with robust antiviral innate immune signaling, T helper 1 (Th1) signaling, and reduced expression of Programmed cell death protein 1 (PD1) on T cells. h4>Conclusions: /h4> Our results suggest that Nef dimerization may be a therapeutic target for adjuvants in immune-mediated HIV cure strategies. Furthermore, Nef dimerization may be a therapeutic target for ameliorating the residual immune dysregulation in antiretroviral therapy-treated chronic HIV-infected individuals.

Loss of function mutations in the human immunodeficiency virus (HIV) negative factor (Nef) gene are associated with reduced viremia, robust T cell immune responses, and delayed acquired immunodeficiency syndrome (AIDS) progression in humans. In vitro studies have shown that mutations in the Nef dimerization interface significantly attenuate viral replication and impair host defense. However, in vivo , mechanistic studies on the role of Nef dimerization in HIV infection are lacking. Humanized rodents with human immune cells are robust platforms for investigating the interactions between HIV and the human immune system. The bone marrow-liver-thymus-spleen (BLTS) humanized mouse model carries human immune cells and lymphoid tissues that facilitate anti-viral immune responses. Here, we employed the BLTS-humanized mouse model to demonstrate that preventing Nef dimerization abrogates HIV viremia and the associated immune dysregulation. This suggests that Nef dimerization may be a therapeutic target for future HIV cure strategies.

The HIV-1 virulence factor Nef promotes high-titer viral replication, immune escape, and pathogenicity. Nef interacts with interleukin-2-inducible T-cell kinase (Itk) and Bruton's tyrosine kinase (Btk), two Tec-family kinases expressed in HIV-1 target cells (CD4 T cells and macrophages, respectively). Using a cell-based bimolecular fluorescence complementation assay, here we demonstrate that Nef recruits both Itk and Btk to the cell membrane and induces constitutive kinase activation in transfected 293T cells. Nef homodimerization-defective mutants retained their interaction with both kinases but failed to induce activation, supporting a role for Nef homodimer formation in the activation mechanism. HIV-1 infection up-regulates endogenous Itk activity in SupT1 T cells and donor-derived peripheral blood mononuclear cells. However, HIV-1 strains expressing Nef variants with mutations in the dimerization interface replicated poorly and were significantly attenuated in Itk activation. We conclude that direct activation of Itk and Btk by Nef at the membrane in HIV-infected cells may override normal immune receptor control of Tec-family kinase activity to enhance the viral life cycle.
© 2020 Li et al.