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CD4+ T follicular helper (TFH) cells are key targets for human immunodeficiency virus (HIV)/simian immunodeficiency virus (SIV) replication and contribute to the virus reservoir under antiretroviral therapy (ART). Here, we describe a novel CD3+ CD20+ double-positive (DP) lymphocyte subset, resident in secondary lymphoid organs of humans and rhesus macaques (RMs), that appear predominantly after membrane exchange between TFH and B cells. DP lymphocytes are enriched in cells displaying a TFH phenotype (CD4+ PD1hi CXCR5hi), function (interleukin 21 positive [IL-21+]), and gene expression profile. Importantly, expression of CD40L upon brief in vitro mitogen stimulation identifies, by specific gene-expression signatures, DP cells of TFH-cell origin versus those of B-cell origin. Analysis of 56 RMs showed that DP cells (i) significantly increase following SIV infection, (ii) are reduced after 12 months of ART in comparison to pre-ART levels, and (iii) expand to a significantly higher frequency following ART interruption. Quantification of total SIV-gag DNA on sorted DP cells from chronically infected RMs showed that these cells are susceptible to SIV infection. These data reinforce earlier observations that CD20+ T cells are infected and expanded by HIV infection, while suggesting that these cells phenotypically overlap activated CD4+ TFH cells that acquire CD20 expression via trogocytosis and can be targeted as part of therapeutic strategies aimed at HIV remission. IMPORTANCE The HIV reservoir is largely composed of latently infected memory CD4+ T cells that persist during antiretroviral therapy and constitute a major barrier toward HIV eradication. In particular, CD4+ T follicular helper cells have been demonstrated as key targets for viral replication and persistence under ART. In lymph nodes from HIV-infected humans and SIV-infected rhesus macaques, we show that CD3+ CD20+ lymphocytes emerge after membrane exchange between T cells and B cells and are enriched in phenotypic, functional, and gene expression profiles found in T follicular helper cells. Furthermore, in SIV-infected rhesus macaques, these cells expand following experimental infection and after interruption of ART and harbor SIV DNA at levels similar to those found in CD4+ T cells; thus, CD3+ CD20+ lymphocytes are susceptible to SIV infection and can contribute to SIV persistence. [ABSTRACT FROM AUTHOR]

Numerous studies have demonstrated that CD8+ T lymphocytes suppress virus replication during human immunodeficiency virus (HIV)/simian immunodeficiency virus (SIV) infection. However, the mechanisms underlying this activity of T cells remain incompletely understood. Here, we conducted CD8+ T lymphocyte depletion in 15 rhesus macaques (RMs) infected intravenously (i.v.) with SIVmac239. At day 70 postinfection, the animals (10 progressors with high viremia and 5 controllers with low viremia) were CD8 depleted by i.v. administration of the antibody M-T807R1. As expected, CD8 depletion resulted in increased virus replication, more prominently in controllers than progressors, which correlated inversely with predepletion viremia. Of note, the feature of CD8+ T lymphocyte predepletion that correlated best with the increase in viremia postdepletion was the level of CD8+ T-bet+ lymphocytes. We next found that CD8 depletion resulted in a homogenous increase of SIV RNA in superficial and mesenteric lymph nodes, spleen, and the gastrointestinal tract of both controllers and progressors. Interestingly, the level of SIV DNA increased postdepletion in both CD4+ central memory T lymphocytes (TCM) and CD4+ effector memory T lymphocytes (TEM) in progressor RMs but decreased in the CD4+ TCM of 4 out of 5 controllers. Finally, we found that CD8 depletion is associated with a greater increase in CD4+ T lymphocyte activation (measured by Ki-67 expression) in controllers than in progressors. Overall, these data reveal a differential impact of CD8+ T lymphocyte depletion between controller and progressor SIV-infected RMs, emphasizing the complexity of the in vivo antiviral role of CD8+T lymphocytes. IMPORTANCE In this study, we further dissect the impact of CD8+ T lymphocytes on HIV/SIV replication during SIV infection. CD8+ T lymphocyte depletion leads to a relatively homogenous increase in viral replication in peripheral blood and tissues. CD8+ T lymphocyte depletion resulted in a more prominent increase in viral loads and CD4+ T lymphocyte activation in controllers than in progressors. Interestingly, we found T-bet expression on CD8+ T lymphocytes to be the best predictor of viral load increase following depletion. The levels of SIV DNA increase postdepletion in both CD4+ TCM and TEM in progressor RMs but decrease in the CD4+ TCM of controllers. The findings described in this study provide key insights into the differential functions of CD8+ T lymphocytes in controller and progressor RMs. [ABSTRACT FROM AUTHOR]

The possibility that vaccination with adenovirus (AdV) vectors increased mucosal T cell activation remains a central hypothesis to explain the potential enhancement of HIV acquisition within the Step trial. Modeling this within rhesus macaques is complicated because human adenoviruses, including human adenovirus type 5 (HAdV-5), are not endogenous to macaques. Here, we tested whether vaccination with a rhesus macaque-derived adenoviral vector (simian adenovirus 7 [SAdV-7]) enhances mucosal T cell activation within rhesus macaques. Following intramuscular SAdV-7 vaccination, we observed a pronounced increase in SAdV-7-specific CD4+ T cell responses in peripheral blood and, more dramatically, in rectal mucosa tissue. Vaccination also induced a significant increase in the frequency of activated memory CD4+ T cells in SAdV-7- and HAdV-5-vaccinated animals in the rectal mucosa but not in peripheral blood. These fluctuations within the rectal mucosa were also associated with a pronounced decrease in the relative frequency of naive resting CD4+ T cells. Together, these results indicate that peripheral vaccination with an AdV vector can increase the activation of mucosal CD4+ T cells, potentially providing an experimental model to further evaluate the role of host-vector interactions in increased HIV acquisition after AdV vector vaccination. [ABSTRACT FROM AUTHOR]

A clear understanding of the antiviral effects of CD8+ T cells in the context of chronic human immunodeficiency virus (HIV) infection is critical for the development of prophylactic vaccines and therapeutics designed to support T-cell-mediated immunity. However, defining the potential correlates of effective CD8+ T-cell immunity has proven difficult; notably, comprehensive analyses have demonstrated that the size and shape of the CD8+ T-cell response are not necessarily indicative of efficacy determined by measures of plasma viral load. Here, we conducted a detailed quantitative and qualitative analysis of CD8+ T-cell responses to autologous virus in a cohort of six HIV-infected individuals with a history of structured interruption of antiretroviral therapy (ART) (SIT). The magnitude and breadth of the HIV-specific response did not, by themselves, explain the changes observed in plasma virus levels after the cessation of ART. Furthermore, mutational escape from targeted epitopes could not account for the differential virological outcomes in this cohort. However, the functionality of HIV-specific CD8+ T-cell populations upon antigen encounter, determined by the simultaneous and independent measurement of five CD8+ T-cell functions (degranulation and gamma interferon, macrophage inflammatory protein 1β, tumor necrosis factor alpha, and interleukin-2 levels) reflected the emergent level of plasma virus, with multiple functions being elicited in those individuals with lower levels of viremia after SIT. These data show that the quality of the HIV-specific CD8+ T-cell response, rather than the quantity, is associated with the dynamics of viral replication in the absence of ART and suggest that the effects of SIT can be assessed by measuring the functional profile of HIV-specific CD8+ T cells. [ABSTRACT FROM AUTHOR]

Unlabelled: Numerous studies have demonstrated that CD8(+) T lymphocytes suppress virus replication during human immunodeficiency virus (HIV)/simian immunodeficiency virus (SIV) infection. However, the mechanisms underlying this activity of T cells remain incompletely understood. Here, we conducted CD8(+) T lymphocyte depletion in 15 rhesus macaques (RMs) infected intravenously (i.v.) with SIVmac239. At day 70 postinfection, the animals (10 progressors with high viremia and 5 controllers with low viremia) were CD8 depleted by i.v. administration of the antibody M-T807R1. As expected, CD8 depletion resulted in increased virus replication, more prominently in controllers than progressors, which correlated inversely with predepletion viremia. Of note, the feature of CD8(+) T lymphocyte predepletion that correlated best with the increase in viremia postdepletion was the level of CD8(+) T-bet(+) lymphocytes. We next found that CD8 depletion resulted in a homogenous increase of SIV RNA in superficial and mesenteric lymph nodes, spleen, and the gastrointestinal tract of both controllers and progressors. Interestingly, the level of SIV DNA increased postdepletion in both CD4(+) central memory T lymphocytes (TCM) and CD4(+) effector memory T lymphocytes (TEM) in progressor RMs but decreased in the CD4(+) TCM of 4 out of 5 controllers. Finally, we found that CD8 depletion is associated with a greater increase in CD4(+) T lymphocyte activation (measured by Ki-67 expression) in controllers than in progressors. Overall, these data reveal a differential impact of CD8(+) T lymphocyte depletion between controller and progressor SIV-infected RMs, emphasizing the complexity of the in vivo antiviral role of CD8(+) T lymphocytes., Importance: In this study, we further dissect the impact of CD8(+) T lymphocytes on HIV/SIV replication during SIV infection. CD8(+) T lymphocyte depletion leads to a relatively homogenous increase in viral replication in peripheral blood and tissues. CD8(+) T lymphocyte depletion resulted in a more prominent increase in viral loads and CD4(+) T lymphocyte activation in controllers than in progressors. Interestingly, we found T-bet expression on CD8(+) T lymphocytes to be the best predictor of viral load increase following depletion. The levels of SIV DNA increase postdepletion in both CD4(+) TCM and TEM in progressor RMs but decrease in the CD4(+) TCM of controllers. The findings described in this study provide key insights into the differential functions of CD8(+) T lymphocytes in controller and progressor RMs., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)

Unlabelled: The possibility that vaccination with adenovirus (AdV) vectors increased mucosal T cell activation remains a central hypothesis to explain the potential enhancement of HIV acquisition within the Step trial. Modeling this within rhesus macaques is complicated because human adenoviruses, including human adenovirus type 5 (HAdV-5), are not endogenous to macaques. Here, we tested whether vaccination with a rhesus macaque-derived adenoviral vector (simian adenovirus 7 [SAdV-7]) enhances mucosal T cell activation within rhesus macaques. Following intramuscular SAdV-7 vaccination, we observed a pronounced increase in SAdV-7-specific CD4(+) T cell responses in peripheral blood and, more dramatically, in rectal mucosa tissue. Vaccination also induced a significant increase in the frequency of activated memory CD4(+) T cells in SAdV-7- and HAdV-5-vaccinated animals in the rectal mucosa but not in peripheral blood. These fluctuations within the rectal mucosa were also associated with a pronounced decrease in the relative frequency of naive resting CD4(+) T cells. Together, these results indicate that peripheral vaccination with an AdV vector can increase the activation of mucosal CD4(+) T cells, potentially providing an experimental model to further evaluate the role of host-vector interactions in increased HIV acquisition after AdV vector vaccination., Importance: The possibility that vaccination with a human adenovirus 5 vector increased mucosal T cell activation remains a central hypothesis to explain the potential enhancement of human immunodeficiency virus (HIV) acquisition within the Step trial. In this study, we tested whether vaccination with a rhesus macaque-derived adenoviral vector in rhesus macaques enhances mucosal CD4(+) T cell activation, the main cell target of simian immunodeficiency virus (SIV)/HIV. The results showed that vaccination with an adenoviral vector indeed increases activation of mucosal CD4(+) T cells and potentially increases susceptibility to SIV infection., (Copyright © 2014, American Society for Microbiology. All Rights Reserved.)

A clear understanding of the antiviral effects of CD8(+) T cells in the context of chronic human immunodeficiency virus (HIV) infection is critical for the development of prophylactic vaccines and therapeutics designed to support T-cell-mediated immunity. However, defining the potential correlates of effective CD8(+) T-cell immunity has proven difficult; notably, comprehensive analyses have demonstrated that the size and shape of the CD8(+) T-cell response are not necessarily indicative of efficacy determined by measures of plasma viral load. Here, we conducted a detailed quantitative and qualitative analysis of CD8(+) T-cell responses to autologous virus in a cohort of six HIV-infected individuals with a history of structured interruption of antiretroviral therapy (ART) (SIT). The magnitude and breadth of the HIV-specific response did not, by themselves, explain the changes observed in plasma virus levels after the cessation of ART. Furthermore, mutational escape from targeted epitopes could not account for the differential virological outcomes in this cohort. However, the functionality of HIV-specific CD8(+) T-cell populations upon antigen encounter, determined by the simultaneous and independent measurement of five CD8(+) T-cell functions (degranulation and gamma interferon, macrophage inflammatory protein 1beta, tumor necrosis factor alpha, and interleukin-2 levels) reflected the emergent level of plasma virus, with multiple functions being elicited in those individuals with lower levels of viremia after SIT. These data show that the quality of the HIV-specific CD8(+) T-cell response, rather than the quantity, is associated with the dynamics of viral replication in the absence of ART and suggest that the effects of SIT can be assessed by measuring the functional profile of HIV-specific CD8(+) T cells.