scholarly journals Reduced Protection from Simian Immunodeficiency Virus SIVmac251 Infection Afforded by Memory CD8+ T Cells Induced by Vaccination during CD4+ T-Cell Deficiency

2008 ◽  
Vol 82 (19) ◽  
pp. 9629-9638 ◽  
Author(s):  
Monica Vaccari ◽  
Joseph Mattapallil ◽  
Kaimei Song ◽  
Wen-Po Tsai ◽  
Anna Hryniewicz ◽  
...  

ABSTRACT Adaptive CD4+ and CD8+ T-cell responses have been associated with control of human immunodeficiency virus/simian immunodeficiency virus (HIV/SIV) replication. Here, we have designed a study with Indian rhesus macaques to more directly assess the role of CD8 SIV-specific responses in control of viral replication. Macaques were immunized with a DNA prime-modified vaccinia virus Ankara (MVA)-SIV boost regimen under normal conditions or under conditions of antibody-induced CD4+ T-cell deficiency. Depletion of CD4+ cells was performed in the immunized macaques at the peak of SIV-specific CD4+ T-cell responses following the DNA prime dose. A group of naïve macaques was also treated with the anti-CD4 depleting antibody as a control, and an additional group of macaques immunized under normal conditions was depleted of CD8+ T cells prior to challenge exposure to SIVmac251. Analysis of the quality and quantity of vaccine-induced CD8+ T cells demonstrated that SIV-specific CD8+ T cells generated under conditions of CD4+ T-cell deficiency expressed low levels of Bcl-2 and interleukin-2 (IL-2), and plasma virus levels increased over time. Depletion of CD8+ T cells prior to challenge exposure abrogated vaccine-induced protection as previously shown. These data support the notion that adaptive CD4+ T cells are critical for the generation of effective CD8+ T-cell responses to SIV that, in turn, contribute to protection from AIDS. Importantly, they also suggest that long-term protection from disease will be afforded only by T-cell vaccines for HIV that provide a balanced induction of CD4+ and CD8+ T-cell responses and protect against early depletion of CD4+ T cells postinfection.

2009 ◽  
Vol 83 (11) ◽  
pp. 5514-5524 ◽  
Author(s):  
Takuya Yamamoto ◽  
Nami Iwamoto ◽  
Hiroyuki Yamamoto ◽  
Tetsuo Tsukamoto ◽  
Tetsuya Kuwano ◽  
...  

ABSTRACT Rapid depletion of memory CD4+ T cells and delayed induction of neutralizing antibody (NAb) responses are characteristics of human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) infections. Although it was speculated that postinfection NAb induction could have only a limited suppressive effect on primary HIV replication, a recent study has shown that a single passive NAb immunization of rhesus macaques 1 week after SIV challenge can result in reduction of viral loads at the set point, indicating a possible contribution of postinfection NAb responses to virus control. However, the mechanism accounting for this NAb-triggered SIV control has remained unclear. Here, we report rapid induction of virus-specific polyfunctional T-cell responses after the passive NAb immunization postinfection. Analysis of SIV Gag-specific responses of gamma interferon, tumor necrosis factor alpha, interleukin-2, macrophage inflammatory protein 1β, and CD107a revealed that the polyfunctionality of Gag-specific CD4+ T cells, as defined by the multiplicity of these responses, was markedly elevated in the acute phase in NAb-immunized animals. In the chronic phase, despite the absence of detectable NAbs, virus control was maintained, accompanied by polyfunctional Gag-specific T-cell responses. These results implicate virus-specific polyfunctional CD4+ T-cell responses in this NAb-triggered virus control, suggesting possible synergism between NAbs and T cells for control of HIV/SIV replication.


2012 ◽  
Vol 87 (3) ◽  
pp. 1359-1372 ◽  
Author(s):  
Wendy G. Tan ◽  
Hyun-Tak Jin ◽  
Erin E. West ◽  
Pablo Penaloza-MacMaster ◽  
Andreas Wieland ◽  
...  

ABSTRACTAdenovirus (Ad) vectors are widely used as experimental vaccines against several infectious diseases, but the magnitude, phenotype, and functionality of CD8+T cell responses induced by different adenovirus serotypes have not been compared. To address this question, we have analyzed simian immunodeficiency virus Gag-specific CD8+T cell responses in mice following vaccination with Ad5, Ad26, and Ad35. Our results show that although Ad5 is more immunogenic than Ad26 and Ad35, the phenotype, function, and recall potential of memory CD8+T cells elicited by these vectors are substantially different. Ad26 and Ad35 vectors generated CD8+T cells that display the phenotype and function of long-lived memory T cells, whereas Ad5 vector-elicited CD8+T cells are of a more terminally differentiated phenotype. In addition, hepatic memory CD8+T cells elicited by Ad26 and Ad35 mounted more robust recall proliferation following secondary challenge than those induced by Ad5. Furthermore, the boosting potential was higher following priming with alternative-serotype Ad vectors than with Ad5 vectors in heterologous prime-boost regimens. Anamnestic CD8+T cell responses were further enhanced when the duration between priming and boosting was extended from 30 to 60 days. Our results demonstrate that heterologous prime-boost vaccine regimens with alternative-serotype Ad vectors elicited more functional memory CD8+T cells than any of the regimens containing Ad5. In summary, these results suggest that alternative-serotype Ad vectors will prove useful as candidates for vaccine development against human immunodeficiency virus type 1 and other pathogens and also emphasize the importance of a longer rest period between prime and boost for generating optimal CD8+T cell immunity.


2008 ◽  
Vol 82 (11) ◽  
pp. 5618-5630 ◽  
Author(s):  
Ronald S. Veazey ◽  
Paula M. Acierno ◽  
Kimberly J. McEvers ◽  
Susanne H. C. Baumeister ◽  
Gabriel J. Foster ◽  
...  

ABSTRACT Previously we have shown that CD8+ T cells are critical for containment of simian immunodeficiency virus (SIV) viremia and that rapid and profound depletion of CD4+ T cells occurs in the intestinal tract of acutely infected macaques. To determine the impact of SIV-specific CD8+ T-cell responses on the magnitude of the CD4+ T-cell depletion, we investigated the effect of CD8+ lymphocyte depletion during primary SIV infection on CD4+ T-cell subsets and function in peripheral blood, lymph nodes, and intestinal tissues. In peripheral blood, CD8+ lymphocyte-depletion changed the dynamics of CD4+ T-cell loss, resulting in a more pronounced loss 2 weeks after infection, followed by a temporal rebound approximately 2 months after infection, when absolute numbers of CD4+ T cells were restored to baseline levels. These CD4+ T cells showed a markedly skewed phenotype, however, as there were decreased levels of memory cells in CD8+ lymphocyte-depleted macaques compared to controls. In intestinal tissues and lymph nodes, we observed a significantly higher loss of CCR5+ CD45RA− CD4+ T cells in CD8+ lymphocyte-depleted macaques than in controls, suggesting that these SIV-targeted CD4+ T cells were eliminated more efficiently in CD8+ lymphocyte-depleted animals. Also, CD8+ lymphocyte depletion significantly affected the ability to generate SIV Gag-specific CD4+ T-cell responses and neutralizing antibodies. These results reemphasize that SIV-specific CD8+ T-cell responses are absolutely critical to initiate at least partial control of SIV infection.


2008 ◽  
Vol 83 (3) ◽  
pp. 1501-1510 ◽  
Author(s):  
Rosemarie D. Mason ◽  
Sheilajen Alcantara ◽  
Viv Peut ◽  
Liyen Loh ◽  
Jeffrey D. Lifson ◽  
...  

ABSTRACT Practical immunotherapies for human immunodeficiency virus infection are needed. We evaluated inactivated simian immunodeficiency virus (SIV) pulsed onto fresh peripheral blood mononuclear cells in 12 pigtail macaques with chronic SIVmac251 infection for T-cell immunogenicity in a randomized cross-over design study. The immunotherapy was safe and convincingly induced high levels of SIV-specific CD4+ T-cell responses (mean, 5.9% ± 1.3% of all CD4+ T cells) and to a lesser extent SIV-specific CD8+ T-cell responses (mean, 0.7% ± 0.4%). Responses were primarily directed toward Gag and less frequently toward Env but not Pol or regulatory/accessory SIV proteins. T-cell responses against Gag were generally broad and polyfunctional, with a mean of 2.7 CD4+ T-cell epitopes mapped per animal and more than half of the SIV Gag-specific CD4+ T cells expressing three or more effector molecules. The immunogenicity was comparable to that found in previous studies of peptide-pulsed blood cells. Despite the high-level immunogenicity, no reduction in viral load was observed in the chronically viremic macaques. This contrasts with our studies of immunization with peptide-pulsed blood cells during early SIV infection in macaques. Future studies of inactivated virus-pulsed blood cell immunotherapy during early infection of patients receiving antiretroviral therapy are warranted.


2008 ◽  
Vol 83 (6) ◽  
pp. 2770-2777 ◽  
Author(s):  
José-Manuel Lozano Reina ◽  
David Favre ◽  
Zeljka Kasakow ◽  
Véronique Mayau ◽  
Marie-Thérèse Nugeyre ◽  
...  

ABSTRACT Nonpathogenic simian immunodeficiency virus SIVagm infection of African green monkeys (AGMs) is characterized by the absence of a robust antibody response against Gag p27. To determine if this is accompanied by a selective loss of T-cell responses to Gag p27, we studied CD4+ and CD8+ T-cell responses against Gag p27 and other SIVagm antigens in the peripheral blood and lymph nodes of acutely and chronically infected AGMs. Our data show that AGMs can mount a T-cell response against Gag p27, indicating that the absence of anti-p27 antibodies is not due to the absence of Gag p27-specific T cells.


2003 ◽  
Vol 77 (5) ◽  
pp. 2998-3006 ◽  
Author(s):  
Dejiang Zhou ◽  
Xiaomin Lai ◽  
Yun Shen ◽  
Prabhat Sehgal ◽  
Ling Shen ◽  
...  

ABSTRACT Adaptive immune responses of γδ T cells during active mycobacterial coinfection of human immunodeficiency virus-infected humans have not been studied. Macaques infected with the simian immunodeficiency virus (SIV) SIVmac were employed to determine the extent to which a coincident AIDS virus infection might compromise immune responses of mycobacterium-specific Vγ2Vδ2+ T cells during active mycobacterial infection. Control SIVmac-negative macaques developed primary and recall expansions of phosphoantigen-specific Vγ2Vδ2+ T cells after Mycobacterium bovis BCG infection and BCG reinfection, respectively. In contrast, SIVmac-infected macaques did not exhibit sound primary and recall expansions of Vγ2Vδ2+ T cells in the blood and pulmonary alveoli following BCG infection and reinfection. The absence of adaptive Vγ2Vδ2+ T-cell responses was associated with profound CD4+ T-cell deficiency and subsequent development of SIVmac-related tuberculosis-like disease in the coinfected monkeys. Consistently, Vγ2Vδ2+ T cells from coinfected monkeys displayed a reduced capacity to expand in vitro following stimulation with phosphoantigen. The reduced ability of Vγ2Vδ2+ peripheral blood lymphocytes (PBL) to expand could be restored to some extent by coculture of these cells with CD4+ T cells purified from PBL of SIV-negative monkeys. Furthermore, naïve monkeys inoculated simultaneously with SIVmac and BCG were unable to sustain expansion of Vγ2Vδ2+ T cells at the time that the coinfected monkeys developed lymphoid depletion and a fatal tuberculosis-like disease. Nevertheless, no deletion in Vδ2 T-cell receptor repertoire was identified in SIVmac-BCG-coinfected macaques, implicating an SIVmac-induced down-regulation rather than a clonal exhaustion of these cells. Thus, an SIVmac-induced compromise of the adaptive Vγ2Vδ2+ T-cell responses may contribute to the immunopathogenesis of the SIV-related tuberculosis-like disease in macaques.


2012 ◽  
Vol 209 (4) ◽  
pp. 641-651 ◽  
Author(s):  
Afam A. Okoye ◽  
Mukta Rohankhedkar ◽  
Chike Abana ◽  
Audrie Pattenn ◽  
Matthew Reyes ◽  
...  

The development of AIDS in chronic HIV/simian immunodeficiency virus (SIV) infection has been closely linked to progressive failure of CD4+ memory T cell (TM) homeostasis. CD4+ naive T cells (TN) also decline in these infections, but their contribution to disease progression is less clear. We assessed the role of CD4+ TN in SIV pathogenesis using rhesus macaques (RMs) selectively and permanently depleted of CD4+ TN before SIV infection. CD4+ TN-depleted and CD4+ TN-repleted RMs were created by subjecting juvenile RMs to thymectomy versus sham surgery, respectively, followed by total CD4+ T cell depletion and recovery from this depletion. Although thymectomized and sham-treated RMs manifested comparable CD4+ TM recovery, only sham-treated RMs reconstituted CD4+ TN. CD4+ TN-depleted RMs responded to SIVmac239 infection with markedly attenuated SIV-specific CD4+ T cell responses, delayed SIVenv-specific Ab responses, and reduced SIV-specific CD8+ T cell responses. However, CD4+ TN-depleted and -repleted groups showed similar levels of SIV replication. Moreover, CD4+ TN deficiency had no significant effect on CD4+ TM homeostasis (either on or off anti-retroviral therapy) or disease progression. These data demonstrate that the CD4+ TN compartment is dispensable for CD4+ TM homeostasis in progressive SIV infection, and they confirm that CD4+ TM comprise a homeostatically independent compartment that is intrinsically capable of self-renewal.


2009 ◽  
Vol 83 (18) ◽  
pp. 9339-9346 ◽  
Author(s):  
Tetsuo Tsukamoto ◽  
Akiko Takeda ◽  
Takuya Yamamoto ◽  
Hiroyuki Yamamoto ◽  
Miki Kawada ◽  
...  

ABSTRACT Despite many efforts to develop AIDS vaccines eliciting virus-specific T-cell responses, whether induction of these memory T cells by vaccination before human immunodeficiency virus (HIV) exposure can actually contribute to effective T-cell responses postinfection remains unclear. In particular, induction of HIV-specific memory CD4+ T cells may increase the target cell pool for HIV infection because the virus preferentially infects HIV-specific CD4+ T cells. However, virus-specific CD4+ helper T-cell responses are thought to be important for functional CD8+ cytotoxic-T-lymphocyte (CTL) induction in HIV infection, and it has remained unknown whether HIV-specific memory CD8+ T cells induced by vaccination without HIV-specific CD4+ T-cell help can exert effective responses after virus exposure. Here we show the impact of CD8+ T-cell memory induction without virus-specific CD4+ T-cell help on the control of a simian immunodeficiency virus (SIV) challenge in rhesus macaques. We developed a prophylactic vaccine by using a Sendai virus (SeV) vector expressing a single SIV Gag241-249 CTL epitope fused with enhanced green fluorescent protein (EGFP). Vaccination resulted in induction of SeV-EGFP-specific CD4+ T-cell and Gag241-249-specific CD8+ T-cell responses. After a SIV challenge, the vaccinees showed dominant Gag241-249-specific CD8+ T-cell responses with higher effector memory frequencies in the acute phase and exhibited significantly reduced viral loads. These results demonstrate that virus-specific memory CD8+ T cells induced by vaccination without virus-specific CD4+ T-cell help could indeed facilitate SIV control after virus exposure, indicating the benefit of prophylactic vaccination eliciting virus-specific CTL memory with non-virus-specific CD4+ T-cell responses for HIV control.


2015 ◽  
Vol 89 (21) ◽  
pp. 10802-10820 ◽  
Author(s):  
Mauricio A. Martins ◽  
Damien C. Tully ◽  
Michael A. Cruz ◽  
Karen A. Power ◽  
Marlon G. Veloso de Santana ◽  
...  

ABSTRACTCertain major histocompatibility complex class I (MHC-I) alleles (e.g.,HLA-B*27) are enriched among human immunodeficiency virus type 1 (HIV-1)-infected individuals who suppress viremia without treatment (termed “elite controllers” [ECs]). Likewise,Mamu-B*08expression also predisposes rhesus macaques to control simian immunodeficiency virus (SIV) replication. Given the similarities between Mamu-B*08 and HLA-B*27, SIV-infectedMamu-B*08+animals provide a model to investigate HLA-B*27-mediated elite control. We have recently shown that vaccination with three immunodominant Mamu-B*08-restricted epitopes (Vif RL8, Vif RL9, and Nef RL10) increased the incidence of elite control inMamu-B*08+macaques after challenge with the pathogenic SIVmac239 clone. Furthermore, a correlate analysis revealed that CD8+T cells targeting Nef RL10 was correlated with improved outcome. Interestingly, this epitope is conserved between SIV and HIV-1 and exhibits a delayed and atypical escape pattern. These features led us to postulate that a monotypic vaccine-induced Nef RL10-specific CD8+T-cell response would facilitate the development of elite control inMamu-B*08+animals following repeated intrarectal challenges with SIVmac239. To test this, we vaccinatedMamu-B*08+animals withnefinserts in which Nef RL10 was either left intact (group 1) or disrupted by mutations (group 2). Although monkeys in both groups mounted Nef-specific cellular responses, only those in group 1 developed Nef RL10-specific CD8+T cells. These vaccine-induced effector memory CD8+T cells did not prevent infection. Escape variants emerged rapidly in the group 1 vaccinees, and ultimately, the numbers of ECs were similar in groups 1 and 2. High-frequency vaccine-induced CD8+T cells focused on a single conserved epitope and therefore did not prevent infection or increase the incidence of elite control inMamu-B*08+macaques.IMPORTANCESince elite control of chronic-phase viremia is a classic example of an effective immune response against HIV/SIV, elucidating the basis of this phenomenon may provide useful insights into how to elicit such responses by vaccination. We have previously established that vaccine-induced CD8+T-cell responses against three immunodominant epitopes can increase the incidence of elite control in SIV-infectedMamu-B*08+rhesus macaques—a model of HLA-B*27-mediated elite control. Here, we investigated whether a monotypic vaccine-induced CD8+T-cell response targeting the conserved “late-escaping” Nef RL10 epitope can increase the incidence of elite control inMamu-B*08+monkeys. Surprisingly, vaccine-induced Nef RL10-specific CD8+T cells selected for variants within days after infection and, ultimately, did not facilitate the development of elite control. Elite control is, therefore, likely to involve CD8+T-cell responses against more than one epitope. Together, these results underscore the complexity and multidimensional nature of virologic control of lentivirus infection.


2008 ◽  
Vol 82 (8) ◽  
pp. 4016-4027 ◽  
Author(s):  
David Verhoeven ◽  
Sumathi Sankaran ◽  
Melanie Silvey ◽  
Satya Dandekar

ABSTRACT Gut-associated lymphoid tissue (GALT) is an early target of human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) and a site for severe CD4+ T-cell depletion. Although antiretroviral therapy (ART) is effective in suppressing HIV replication and restoring CD4+ T cells in peripheral blood, restoration in GALT is delayed. The role of restored CD4+ T-cell help in GALT during ART and its impact on antiviral CD8+ T-cell responses have not been investigated. Using the SIV model, we investigated gut CD4+ T-cell restoration in infected macaques, initiating ART during either the primary stage (1 week postinfection), prior to acute CD4+ cell loss (PSI), or during the chronic stage at 10 weeks postinfection (CSI). ART led to viral suppression in GALT and peripheral blood mononuclear cells of PSI and CSI animals at comparable levels. CSI animals had incomplete CD4+ T-cell restoration in GALT. In PSI animals, ART did not prevent acute CD4+ T-cell loss by 2 weeks postinfection in GALT but supported rapid and complete CD4+ T-cell restoration thereafter. This correlated with an accumulation of central memory CD4+ T cells and better suppression of inflammation. Restoration of CD4+ T cells in GALT correlated with qualitative changes in SIV gag-specific CD8+ T-cell responses, with a dominance of interleukin-2-producing responses in PSI animals, while both CSI macaques and untreated SIV-infected controls were dominated by gamma interferon responses. Thus, central memory CD4+ T-cell levels and qualitative antiviral CD8+ T-cell responses, independent of viral suppression, were the immune correlates of gut mucosal immune restoration during ART.


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