HIV and Tuberculosis (TB) co-infection place an immense burden on health care systems as they act in synergy to worsen disease prognoses. TB is the most common cause of death in people living with HIV (PLWH) and in turn, HIV is the most significant risk factor for progressing from latent to active TB disease. While HIV and TB are endemic in sub-Saharan Africa, they also disproportionately affect marginalized populations in Canada. Unfortunately, the only licensed TB vaccine, BCG, does not protect from adult pulmonary TB and is not recommended for PLWH. Thus, the development of novel TB vaccines, which are safe and effective in PLWH, remains an urgent global necessity. We have found that humanized mice (hu-mice) are ideal models to research this as they can be successfully infected with HIV, TB and HIV/TB and recapitulate human disease pathology. The immunogenicity of a next-generation respiratory mucosal (RM) trivalent chimpanzee adenoviral-vectored vaccine (Tri:ChAd:TB) was investigated in hu-mice to determine whether it protects from M.tb infection and overcomes immune suppression in HIV-infected hu-mice. When immunizing naïve hu-mice, a trend of increased M.tb-specific CD4+ T cells producing IFNγ and TNFα in the lungs and spleen was observed. Vaccinated hu-mice challenged with M.tb exhibited significantly reduced lung mycobacterial burden, tissue dissemination and lung pathology. HIV-infected hu-mice that were subsequently immunized and challenged with M.tb led to a decreased trend in mycobacterial load in the lungs and spleen compared to their unvaccinated counterparts, indicating that the vaccine may be able to offer protection against TB when co-infected with HIV. These findings demonstrate the protective potential of the RM Tri:ChAd:TB vaccine against TB disease for PLWH. In the future, we will repeat our findings and test this vaccine in antiretroviral treated HIV-infected hu-mice to increase clinical significance in the context of current therapeutics.

Background
Antiretroviral therapy (ART) can suppress HIV viremia to undetectable levels in PLWH, but upon ART withdraw, viremia rebounds, indicating the establishment of latently-infected cells even under prolonged ART. Naïve and memory CD4+ T cells recirculate through secondary lymphoid organs, where they continuously contact dendritic cells and are exposed to high IL-7 levels that are required for their long-term maintenance. In this study, we asked whether similar mechanisms can be co-opted to maintain latently-infected T cells under ART.
Methods
We generated a dual-fluorescent HIV reporter system that allows for longitudinal assessment of HIV latency in T cells. We performed a series of co-culture studies with autologous dendritic cells to address how various viral antigens modulate the proliferative/survival responses of latently-infected T cells by flow cytometry. Our experimental readouts included the expression of Gagp24, survival markers and cell-proliferations in primary T cells.
Results
Different DC:T cell ratios caused varying HIV reactivation and T cell proliferation in time course studies, and we identified that some latently-infected T cells can maintain proliferation without detectible virus reactivation. We show that the addition of viral antigens can trigger a proliferative response in a subset of latently-infected T cells, and that DC:T cell contacts drove the expression of pro-survival molecule survivin. Cell-cell contact with DCs results in the differentiation of latently-infected T cells from a predominantly central memory (TCM) to an effector memory (TEM) phenotype, which is consistent with T cell subsets that harbor replication competent provirus in PLWH. Interestingly, DC-mediated proliferation was driven by both MHC-II:TCR interaction and co-stimulatory signaling. Finally, IL-7 signalling induces strong expression of the anti-apoptotic protein bcl-2 in latently-infected CD4+ T cells.
Conclusion: Our study demonstrates that antigen-specific signals through DC:T cell interactions, along with IL-7 signals, can collectively contribute to the maintenance of latent T cell pools under ART suppression.

Introduction: HIV prevention ranges from condoms to biomedical interventions, such as pre-exposure prophylaxis (PrEP), for which uptake is lower in women. Therefore, women need more HIV prevention options. HIV-exposed seronegative (HESN) individuals remain uninfected despite repeated exposures. Some HESN cohorts have observed decreased Tcell and increased natural killer (NK) activation, without affecting the overall immune response to infections. In a pilot clinical study, 6-weeks daily low-dose (81mg) anti-inflammatory acetylsalicylic acid (ASA/aspirin), reduced female genital tract Tcell activation (CD4+CCR5+Tcells) by 39%, suggesting aspirin may induce a broader HESN-like phenotype. Here, we present aspirins effect on NK and Tcells.
Methods: Blood was collected from 40 HIV-uninfected women from Nairobi, Kenya before and after 6-weeks aspirin. NK and T-cell phenotypes/functions were assessed by flow cytometry. Tcell cytokine production/proliferation to peptide pools (CEF (Cytomegalovirus, Epstein Barr, Influenza) and HPV (Human Papilloma Virus)), and NKs by degranulation/cytokine production to PMA-ionomycin/K562s.. Titres of total/influenza-specific IgG were assessed by ELISA. mTOR phosphorylation was assessed by flow cytometry.
Results: Following 6-weeks aspirin, there was increased IFNƴ, IL-2, and TNFα in memory CD4+Tcells, and TNFα in memory CD8+Tcells in response to HPV peptides. There was no change with CEF and no impact of either pool on proliferation. Total blood IgG decreased(p=0.027), though influenza-specific IgG did not. While aspirin didn’t alter NK cell function, there was an increased proportion of activation marker NKp46(p=0.025) and co-expression of CD38+NKp46+NKG2A+(p=0.045), a similar NK phenotype observed in HESN individuals. Exposure to ASA in vitro reduced mTOR phosphorylation in CD4+Tcells by 10%(p=0.021), which correlated with reduced CCR5 expression(p=0.0184).
Conclusion: This study showed that 6-weeks daily ASA reduced HIV target cells and induced a HESN-like phenotype characterized by reduced Tcell and increased NK activation without impacting the recall antigens response potentially through inhibiting the mTOR pathway supporting ASA’s further assessment as a new HIV prevention tool.

Background: Our data have shown that anti-HIV-1 T-cell immunity in people living with HIV-1 (PLWH) could be improved through a better use of autophagy, a key catabolic process allowing cells to diversify their nutrients sources to optimize energy production. However, although we were able to boost autophagy in PLWH with the AMPK inducer AICAR, it was not always possible and often partial when compared to elite controllers (EC). EC display optimal T-cell protection against HIV-1 despite years of infection. Therefore, it is critical to find new ways to induce energy metabolism in the aim of fully rescuing T-cell immunity against HIV-1 in every PLWH regardless of sex, aging, and antiretroviral therapies (ART). Here, we aimed to test in PLWH the impact of two anti-aging and anti-inflammatory drugs, the autophagy inducer spermidine and alpha-ketoglutaric acid (KG).

Methods: We assessed the impact of spermidine and KG treatments on energy-dependent T-cell immunity against HIV-1 in PLWH (EC and ART-treated patients with or without CD4 restoration; ART-treated patients also included men, women, and elderly individuals). Briefly, we assessed mitochondrial respiration capacity/energy production for all conditions with Seahorse flux analyser and anti-HIV-1 immunity by flow cytometry. In this context, polyfunctionality, IL-21 production, and cytotoxic activity have been determined respectively in anti-HIV-1 CD4 and CD8 T-cells.

Results: Our data confirm full rescue of energy-dependent T-cell immunity in ART-treated patients regardless of sex and aging, both with spermidine, KG and spermidine/KG co-treatment. When considering the immune non-responders, who represent treated patients with no CD4 restoration, we found that only spermidine/KG co-treatment was effective in ensuring an optimal improvement of their anti-HIV-1 T-cell functions.

Conclusions: This work confirm that it may be possible in all PLWH, including in immune non-responders and elderly individuals, to boost their anti-HIV-1 T-cell immunity with spermidine/KG supplementation.

HIV viral load (VL) is a predictor of disease progression and transmission, therefor, restriction of VL is key to reducing the amount of people living with HIV (PLWH) and AIDS. VL is variable among individuals and their genetics, particularly in the HLA region, contribute to this variability. HIV escape from HLA restriction is well described and viral mutations can counteract the protective effect of HLA alleles. A genome-wide association study of HIV VL in individuals of African ancestry identified a locus on chromosome 1, near the protein coding gene chromodomain helicase DNA binding protein 1 like (CHD1L), that has a novel association with control of HIV replication. However, not all individuals carrying protective alleles in this locus maintain low VL. In addition, the regions’ impact on viral evolution has not been investigated. To address this, we conducted an analysis in 148 PLWH from South Africa with both human and viral sequence data available. Logistic regression was used to test the association between HIV amino acid variants in reverse transcriptase (RT), protease (PR), gag, and nef with host alleles near CHD1L and in HLA. We observed associations between the CHD1L variants rs77029719, rs7519713, rs59784663 and rs73004025 with codon 248 of HIV RT and between CHD1L variants rs7519713 and rs77029719 with codon 18 of HIV gag. These associations are consistent with viral escape from CHD1L pressure. In addition, we observed associations between HLA B*81 and HLA C*18 with RT codon 4 and HLAB*58 with RT codon 196. We report on a viral escape mutation scan, in a South African population, and show evidence of selective pressure by HLA and variants near CHD1L on RT and gag. Our findings provide new evidence of host genetic variation impacting viral evolution in a population highly affected by HIV.

Interferon-alpha (IFN-α) is known to induce strong antiviral activities. Humans express 12 different IFNα subtypes which activate downstream signaling and induce antiviral responses in a differential manner. Although IFN-α subtypes signal through the same receptor they induce different host restriction factors. Studies have shown that not all IFN-α subtypes induce an adequate antiviral response to every viral infection. We have shown that IFN-α subtypes differentially control HIV-1 infection and modulate immunity in a differential manner. The clinically available IFN-α2 subtype has not been highly effective in reducing viral loads during HIV-1 infection and the endogenous production of IFN-α2 is associated with CD8+ T cell hyperactivation and dysfunction in HIV-1 patients. In contrast, we showed IFN-α14 reduced HIV-1 viral load significantly in infected MT4C5 cell line as well as in the TKO-BLT humanized mouse model. In addition, three weeks of treatment with IFN-α14 significantly reduced markers of CD8+ T cell-related dysfunction such as hyperactivation, exhaustion and apoptosis comparable to healthy control levels. Also, low levels of these markers were maintained even after the treatment was withdrawn. Although IFN-α14 treatment reduced the activation profile and proliferative capacity of total CD8+ T cells, it did not change their ability to secrete cytokines or degranulate upon stimulation ex vivo. Thus, the IFN-α14 subtype may be more clinically effective than the IFN-α2 subtype. Although IFN-α14 subtype treatment reduced viral load both in vitro and in vivo significantly, the question of what restriction factors might play an important role persist.

This work was supported by Saskatchewan Health Research Foundation (SHRF) Canada