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Occasional zoonotic viral attacks on immunologically naive populations result in massive death tolls that are capable of threatening human survival. Currently, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the infectious agent that causes coronavirus disease (COVID-19), has spread from its epicenter in Wuhan China to all parts of the globe. Real-time mapping of new infections across the globe has revealed that variable transmission patterns and pathogenicity are associated with differences in SARS-CoV-2 lineages, clades, and strains. Thus, we reviewed how changes in the SARS-CoV-2 genome and its structural architecture affect viral replication, immune evasion, and transmission within different human populations. We also looked at which immune dominant regions of SARS-CoV-2 and other coronaviruses are recognized by Major Histocompatibility Complex (MHC)/Human Leukocyte Antigens (HLA) genes and how this could impact on subsequent disease pathogenesis. Efforts were also placed on understanding immunological changes that occur when exposed individuals either remain asymptomatic or fail to control the virus and later develop systemic complications. Published autopsy studies that reveal alterations in the lung immune microenvironment, morphological, and pathological changes are also explored within the context of the review. Understanding the true correlates of protection and determining how constant virus evolution impacts on host-pathogen interactions could help identify which populations are at high risk and later inform future vaccine and therapeutic interventions.

Cytotoxic CD4+ T cells (CD4+ CTLs) limit HIV pathogenesis, as evidenced in elite controllers (a subset of individuals who suppress the virus without the need for therapy). CD4+ CTLs have also been shown to kill HIV-infected macrophages. However, little is known about their contribution towards HIV persistence, how they are affected following exposure to immune modulators like morphine, and what factors maintain their frequencies and function. Further, the lack of robust markers to identify CD4+ CTLs in various animal models limits understanding of their role in HIV pathogenesis. We utilized various PBMC samples obtained from SIV infected and cART treated rhesus macaques exposed to morphine or saline and subjected to flow cytometry evaluations. Thereafter, we compared and correlated the expression of CD4+ CTL-specific markers to viral load and viral reservoir estimations in total CD4+ T cells. We found that CD29 could be reliably used as a marker to identify CD4+ CTLs in rhesus macaques since CD29hi CD4+ T cells secrete higher cytotoxic and proinflammatory cytokines following PMA/ionomycin or gag stimulation. In addition, this immune cell subset was depleted during untreated SIV infection. Strikingly, we also observed that early initiation of cART reconstitutes depleted CD29hi CD4+ T cells and restores their function. Furthermore, we noted that morphine exposure reduced the secretion of proinflammatory cytokines/cytotoxic molecules in CD29hi CD4+ T cells. Lastly, increased functionality of CD29hi CD4+ T cells as depicted by elevated levels of either IL-21 or granzyme B hi T Bet+ gag specific responses were linked to limiting the size of the replication-competent reservoir during cART treatment. Collectively, our data suggest that CD4+ CTLs are crucial in limiting SIV pathogenesis and persistence.

Background In Sub-Saharan Africa, herbal therapy continues to be utilized for HIV-1 disease management. However, the therapeutic benefits of these substances remain ambiguous. To date, little is known about the effects of these plant extracts on chronic CD4 + T-cell activation and exhaustion which is partly driven by HIV-1 associated microbial translocation. Methods Effects of Azadirachta indica, Momordica foetida and Moringa oleifera ethanol: water mixtures on cell viability were evaluated using the Guava PCA system. Then, an in-vitro cell culture model was developed to mimic CD4+ T cell exposures to antigens following HIV-1 microbial translocation. In this, peripheral blood mononuclear cells (PBMCs) isolated from HIV negative (n = 13), viral load n = 10) and viral load > 1000 copies per mL (n = 6) study participants from rural Uganda were treated with Staphylococcus enterotoxin B (SEB). Then, the candidate plant extract (A. indica) was added to test the potential to inhibit corresponding CD4+ T cell activation. Following BD Facs Canto II event acquisition, variations in %CD38, %CD69, Human Leukocyte Antigen -DR (HLA-DR), Programmed cell death protein 1 (PD-1), T-cell immunoglobulin and mucin domain-containing protein 3 (Tim-3), interferon gamma (IFN γ) and interleukin 2 (IL-2) CD4 + T cell expression were evaluated. Results Following exposure to SEB, only A. indica demonstrated a concentration-dependent ability to downregulate the levels of CD4 + T cell activation. At the final concentration of 0.500 μg/mL of A. indica, a significant downregulation of CD4 + CD38 + HLA-DR+ expression was observed in HIV negative (p P = 0.0313). This plant extract also significantly lowered SEB induced % CD4+ T cell HLADR, PD-1 and Tim-3 levels. PD-1 and CD69 markers were only significantly downmodulated in only the HIV negative ((p = 0.0001 and p = 0.0078 respectively) and viral load Conclusion A. indica exhibited the in-vitro immunomodulatory potential to inhibit the continuum of SEB induced CD4+ T-cell activation/ exhaustion without impacting general T-cell specific functions such as cytokine secretion. Additional studies are needed to confirm A. indica as a source of natural products for targeting persistent immune activation and inflammation during ART.

HIV persists in cellular reservoirs despite effective combined antiretroviral therapy (cART) and there is viremia flare up upon therapy interruption. Opioids modulate the immune system and suppress antiviral gene responses, which significantly impact people living with HIV (PLWH). However, the effect of opioids on viral reservoir dynamics remain elusive. Herein, we developed a morphine dependent SIVmac251 infected Rhesus macaque (RM) model to study the impact of opioids on HIV reservoirs. RMs on a morphine (or saline control) regimen were infected with SIVmac251. The cART was initiated in approximately half the animals five weeks post-infection, and morphine/saline administration continued until the end of the study. Among the untreated RM, we did not find any difference in plasma/CSF or in cell-associated DNA/RNA viral load in anatomical tissues. On the other hand, within the cART suppressed macaques, there was a reduction in cell-associated DNA load, intact proviral DNA levels, and in inducible SIV reservoir in lymph nodes (LNs) of morphine administered RMs. In distinction to LNs, in the CNS, the size of latent SIV reservoirs was higher in the CD11b+ microglia/macrophages in morphine dependent RMs. These results suggest that in the proposed model, morphine plays a differential role in SIV reservoirs by reducing the CD4+ T-cell reservoir in lymphoid tissues, while increasing the microglia/reservoir size in CNS tissue. The findings from this pre-clinical model will serve as a tool for screening therapeutic strategies to reduce/eliminate HIV reservoirs in opioid dependent PLWH.IMPORTANCE Identification and clearance of HIV reservoirs is a major challenge in achieving a cure for HIV. This is further complicated by co-morbidities that may alter the size of the reservoirs. There is an overlap between the risk factors for HIV and opioid abuse. Opiates have been recognized as prominent co-morbidities in HIV-infected populations. People infected with HIV also abusing opioids have immune modulatory effects and more severe neurological disease. However, the impact of opioid abuse on HIV reservoirs remains unclear. In this study, we used morphine dependent SIVmac251 infected rhesus macaque (RM) model to study the impact of opioids on HIV reservoirs. Our studies suggested that people with HIV who abuse opioids had higher reservoirs in CNS than the lymphoid system. Extrapolating the macaque findings in humans suggests that such differential modulation of HIV reservoirs among people living with HIV abusing opioids could be considered for future HIV cure research efforts.

HIV persists in cellular reservoirs despite effective anti-retroviral therapy with rebound of viremia upon therapy interruption. Opioids modulate the immune system and suppress antiviral gene responses, which significantly impact people living with HIV (PLWH). However, the effects of opioids on viral reservoir remains elusive. Herein, we describe a morphine dependent SIVmac251 infected Rhesus macaque (RM) model to study the impact of opioids on HIV reservoirs. RMs were ramped up with morphine (n=10) or saline (n=9) for two weeks to a final dosage of 5mg/kg administered twice daily, which was maintained for seven weeks, and then infected with SIVmac251. Combined anti-retroviral therapy (cART) was initiated in approximately half the animals in each group five weeks post-infection and morphine/saline administration continued for 10 months. Among drug naïve macaques, there were no differences in plasma/CSF viral load nor in cell-associated DNA/RNA loads. However, within the cART-suppressed macaques, there was a reduction in cell-associated DNA load, intact proviral DNA copy numbers, and inducible SIV reservoir in both peripheral blood and lymph nodes (LNs) of morphine-administered RMs compared to saline controls. Further, PBMCs of morphine administered RMs, a reduction in Th1 polarized CD4+ T cells and in LNs there was a reduction in the total Tfh and Th1 like Tfh cells were observed, indicating probably have impact on reduction of viral reservoirs. In distinction to PBMC and LNs, within the CNS size of latent SIV reservoirs was higher in the CD11b+ microglia/macrophages of morphine-dependent RMs. These data suggest that morphine plays a role in modulating SIV reservoirs, reduces the CD4+ T-cell reservoir in both peripheral blood and LNs, and increases microglia/macrophage reservoirs in CNS. These findings will aid in understanding of molecular mechanism(s) of opioid-mediated differential modulation of viral reservoirs and evaluation of therapeutic strategies to reduce/eliminate HIV reservoirs in opioid-dependent PLWH.Author summaryOpioids are commonly used as well as abused by HIV infected individuals, are known to suppress immune responses. However, their effects on modulating viral reservoir dynamics is not known. Here we developed a morphine dependent SIVmac251 infected rhesus macaque (RM) model to study the impact of opioids on HIV reservoirs and immune cells. We found that there was no difference in viral loads or cell-associated DNA/RNA loads among morphine dependent vs. saline treated control macaques. On the other hand, when macaques were treated with cART, there was a reduction in SIV reservoirs both in periphery and lymphoid tissues in morphine administered RMs, and the size of latent SIV reservoir was higher in the CNS CD11b+ microglia/macrophages as compared to control macaques. Therefore, these new data form macaque models suggest that PLWH who suffering from opioid use disorders have higher reservoirs in CNS as compared to lymphoid system. Thus, through understanding these reservoirs among PLWH who uses opioids are critical for better designing HIV cure strategies.

Natural killer (NK) cells are innate immune lymphocytes with a key role in host defense against HIV infection. Recent advances in chimeric antigen receptors (CARs) have made NK cells a prime target for expressing recombinant receptors capable of redirecting NK cytotoxic functions towards HIV-infected cells. In this review, we discuss the role of NK cells in HIV and the mechanisms of actions of HIV-targeting CAR strategies. Furthermore, we also review NK cells signal transduction and its application to CAR NK cell strategies to develop new combinations of CAR intracellular domains and to improve CAR NK signaling and cytotoxic functions.

Zika Virus (ZIKV) is primarily transmitted through mosquito bites. It can also be transmitted during sexual intercourse and in utero from mother to fetus. To gain preliminary insight into ZIKV pathology and immune responses on route of transmission, rhesus macaques (RMs) were inoculated with ZIKV (PRVABC59) via intravaginal (IVAG) (n = 3) or subcutaneous (sub Q) (n = 2) routes. Systemic ZIKV infection was observed in all RMs, regardless of the route of inoculation. After 9 days postinfection (dpi), ZIKV was not detected in the plasma of IVAG- and sub-Q-inoculated RMs. Importantly, RMs harbored ZIKV up to 60 dpi in various anatomical locations. Of note, ZIKV was also present in several regions of the brain, including the caudate nucleus, parietal lobe, cortex, and amygdala. These observations appear to indicate that ZIKV infection may be systemic and persistent regardless of route of inoculation. In addition, we observed changes in key immune cell populations in response to ZIKV infection. Importantly, IVAG ZIKV infection of RMs is associated with increased depletion of CD11C hi myeloid cells, reduced PD-1 expression in NK cells, and elevated frequencies of Ki67+ CD8+ central memory cells as compared to sub Q ZIKV-infected RMs. These results need to interpreted with caution due to the small number of animals utilized in this study. Future studies involving large groups of animals that have been inoculated through both routes of transmission are needed to confirm our findings.

The significance of HIV-associated immune activation and microbial translocation in Sub-Saharan African population remains poorly defined. We assessed biomarkers of inflammation, microbial translocation, and cellular activation and found most factors elevated in Ugandan HIV-1 seroconverters compared with community-matched controls. In contrast to previous findings in Western cohorts, C-reactive protein, neopterin, and intestinal fatty acid binding protein were not elevated. Higher T-cell activation and IL-6 were associated with faster disease progression. Surprisingly, intestinal fatty acid binding protein, indicative of enterocyte turnover, was higher in slow than in fast progressors. These data suggest differential relationships among biomarkers of intestinal barrier integrity and innate immune activation between developed countries and Sub-Saharan Africa.