Specific Pathogen-Free Status Alters Immunophenotype in Rhesus Macaques: Implications for the Study of Simian Immunodeficiency Virus

Transforming growth factor-β signaling (TGF-β) maintains a balanced physiological function including cell growth, differentiation, and proliferation and regulation of immune system by modulating either SMAD2/3 and SMAD7 (SMAD-dependent) or SMAD-independent signaling pathways under normal conditions. Increased production of TGF-β promotes immunosuppression in Human Immunodeficiency Virus (HIV)/Simian Immunodeficiency Virus (SIV) infection. However, the cellular source and downstream events of increased TGF-β production that attributes to its pathological manifestations remain unknown. Here, we have shown increased production of TGF-β in a majority of intestinal CD3−CD20−CD68+ cells from acute and chronically SIV infected rhesus macaques, which negatively correlated with the frequency of jejunum CD4+ T cells. No significant changes in intestinal TGF-β receptor II expression were observed but increased production of the pSMAD2/3 protein and SMAD3 gene expression in jejunum tissues that were accompanied by a downregulation of SMAD7 protein and gene expression. Enhanced TGF-β production by intestinal CD3−CD20−CD68+ cells and increased TGF-β/SMAD-dependent signaling might be due to a disruption of a negative feedback loop mediated by SMAD7. This suggests that SIV infection impacts the SMAD-dependent signaling pathway of TGF-β and provides a potential framework for further study to understand the role of viral factor(s) in modulating TGF-β production and downregulating SMAD7 expression in SIV. Regulation of mucosal TGF-β expression by therapeutic TGF-β blockers may help to create effective antiviral mucosal immune responses.

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A Truncated Form of Nef Selected during Pathogenic Reversion of Simian Immunodeficiency Virus SIVmac239Δnef Increases Viral Replication

Journal of Virology ◽

10.1128/jvi.77.2.1245-1256.2003 ◽

2003 ◽

Vol 77 (2) ◽

pp. 1245-1256 ◽

Cited By ~ 32

Author(s):

Lisa A. Chakrabarti ◽

Karin J. Metzner ◽

Tijana Ivanovic ◽

Hua Cheng ◽

Jean Louis-Virelizier ◽

...

Keyword(s):

T Cell ◽

Viral Replication ◽

Simian Immunodeficiency Virus ◽

Rhesus Macaques ◽

Premature Stop Codon ◽

Cell Depletion ◽

Partial Recovery ◽

Wild Type ◽

T Cell Depletion ◽

Immunodeficiency Virus

ABSTRACT The live, attenuated vaccine simian immunodeficiency virus SIVmac239Δnef efficiently protects rhesus macaques against infection with wild-type SIVmac but occasionally causes CD4+ T-cell depletion and progression to simian AIDS (SAIDS). Virus recovered from a vaccinated macaque (Rh1490) that progressed to SAIDS had acquired an additional deletion in the nef gene, resulting in a frameshift that restored the original nef open reading frame (R. I. Connor, D. C. Montefiori, J. M. Binley, J. P. Moore, S. Bonhoeffer, A. Gettie, E. A. Fenamore, K. E. Sheridan, D. D. Ho, P. J. Dailey, and P. A. Marx, J. Virol. 72:7501-7509, 1998). Intravenous inoculation of the Rh1490 viral isolate into four naive rhesus macaques induced CD4+ T-cell depletion and disease in three out of four animals within 2 years, indicating a restoration of virulence. A DNA fragment encompassing the truncated nef gene amplified from the Rh1490 isolate was inserted into the genetic backbone of SIVmac239. The resulting clone, SIVmac239-Δ2nef, expressed a Nef protein of approximately 23 kDa, while the original SIVmac239Δnef clone expressed a shorter protein of 8 kDa. The revertant form of Nef did not cause downregulation of CD4, CD3, or major histocompatibility complex class I. The infectivity of SIVmac239-Δ2nef was similar to that of SIVmac239Δnef in single-cycle assays using indicator cell lines. In contrast, SIVmac239-Δ2nef replicated more efficiently than SIVmac239Δnef in peripheral blood mononuclear cell (PBMC) cultures infected under unstimulated conditions. The p27 Gag antigen levels in SIVmac239-Δ2nef-infected cultures were still lower than those obtained with wild-type SIVmac239, consistent with a partial recovery of Nef function. The transcriptional activity of long terminal repeat (LTR)-luciferase constructs containing the nef deletions did not differ markedly from that of wild-type LTR. Introduction of a premature stop codon within Nef-Δ2 abolished the replicative advantage in PBMCs, demonstrating that the Nef-Δ2 protein, rather than the structure of the U3 region of the LTR, was responsible for the increase in viral replication. Taken together, these results show that SIV with a deletion in the nef gene can revert to virulence and that expression of a form of nef with multiple deletions may contribute to this process by increasing viral replication.

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TRIM5α Resistance Escape Mutations in the Capsid Are Transferable between Simian Immunodeficiency Virus Strains

Journal of Virology ◽

10.1128/jvi.01620-16 ◽

2016 ◽

Vol 90 (24) ◽

pp. 11087-11095 ◽

Cited By ~ 3

Author(s):

Fan Wu ◽

Andrea Kirmaier ◽

Ellen White ◽

Ilnour Ourmanov ◽

Sonya Whitted ◽

...

Keyword(s):

Amino Acid ◽

Simian Immunodeficiency Virus ◽

Rhesus Macaques ◽

Hiv Vaccine ◽

Sooty Mangabey ◽

Virus Acquisition ◽

Vaccine Trials ◽

Immunodeficiency Virus ◽

Distinct Strain ◽

Virus Strains

ABSTRACT TRIM5α polymorphism limits and complicates the use of simian immunodeficiency virus (SIV) for evaluation of human immunodeficiency virus (HIV) vaccine strategies in rhesus macaques. We previously reported that the TRIM5α-sensitive SIV from sooty mangabeys (SIVsm) clone SIVsmE543-3 acquired amino acid substitutions in the capsid that overcame TRIM5α restriction when it was passaged in rhesus macaques expressing restrictive TRIM5α alleles. Here we generated TRIM5α-resistant clones of the related SIVsmE660 strain without animal passage by introducing the same amino acid capsid substitutions. We evaluated one of the variants in rhesus macaques expressing permissive and restrictive TRIM5α alleles. The SIVsmE660 variant infected and replicated in macaques with restrictive TRIM5α genotypes as efficiently as in macaques with permissive TRIM5α genotypes. These results demonstrated that mutations in the SIV capsid can confer SIV resistance to TRIM5α restriction without animal passage, suggesting an applicable method to generate more diverse SIV strains for HIV vaccine studies. IMPORTANCE Many strains of SIV from sooty mangabey monkeys are susceptible to resistance by common rhesus macaque TRIM5α alleles and result in reduced virus acquisition and replication in macaques that express these restrictive alleles. We previously observed that spontaneous variations in the capsid gene were associated with improved replication in macaques, and the introduction of two amino acid changes in the capsid transfers this improved replication to the parent clone. In the present study, we introduced these mutations into a related but distinct strain of SIV that is commonly used for challenge studies for vaccine trials. These mutations also improved the replication of this strain in macaques with the restrictive TRIM5α genotype and thus will eliminate the confounding effects of TRIM5α in vaccine studies.

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Quintuple Deglycosylation Mutant of Simian Immunodeficiency Virus SIVmac239 in Rhesus Macaques: Robust Primary Replication, Tightly Contained Chronic Infection, and Elicitation of Potent Immunity against the Parental Wild-Type Strain

Journal of Virology ◽

10.1128/jvi.75.9.4023-4028.2001 ◽

2001 ◽

Vol 75 (9) ◽

pp. 4023-4028 ◽

Cited By ~ 40

Author(s):

Kazuyasu Mori ◽

Yasuhiro Yasutomi ◽

Shinji Ohgimoto ◽

Tadashi Nakasone ◽

Shiki Takamura ◽

...

Keyword(s):

Simian Immunodeficiency Virus ◽

Chronic Infection ◽

Neutralizing Antibodies ◽

Rhesus Macaques ◽

Chronic Phase ◽

Wild Type ◽

Live Attenuated Vaccine ◽

Challenge Virus ◽

Culture Cells ◽

Immunodeficiency Virus

ABSTRACT We previously generated a mutant of simian immunodeficiency virus (SIV) lacking 5 of a total of 22 N-glycans in its external envelope protein gp120 with no impairment in viral replication capability and infectivity in tissue culture cells. Here, we infected rhesus macaques with this mutant and found that it also replicated robustly in the acute phase but was tightly, though not completely, contained in the chronic phase. Thus, a critical requirement for the N-glycans for the full extent of chronic infection was demonstrated. No evidence indicating reversion to a wild type was obtained during the observation period of more than 40 weeks. Monkeys infected with the mutant were found to tolerate a challenge infection with wild-type SIV very well. Analyses of host responses following challenge revealed no neutralizing antibodies against the challenge virus but strong secondary responses of cytotoxic T lymphocytes against multiple antigens, including Gag-Pol, Nef, and Env. Thus, the quintuple deglycosylation mutant appeared to represent a novel class of SIV live attenuated vaccine.

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Detection of simian immunodeficiency virus DNA in macrophages from infected rhesus macaques

Journal of Medical Primatology ◽

10.1111/j.1600-0684.1992.tb00571.x ◽

1992 ◽

Vol 21 (2-3) ◽

pp. 74-81

Author(s):

Ronald E. Unger ◽

Marta L. Marthas ◽

Andrew A. Lackner ◽

Elissa Pratt‐Lowe ◽

Barbara L. Lohman ◽

...

Keyword(s):

Simian Immunodeficiency Virus ◽

Rhesus Macaques ◽

Immunodeficiency Virus

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Characterization and Implementation of a Diverse Simian Immunodeficiency Virus SIVsm Envelope Panel in the Assessment of Neutralizing Antibody Breadth Elicited in Rhesus Macaques by Multimodal Vaccines Expressing the SIVmac239 Envelope

Journal of Virology ◽

10.1128/jvi.01221-14 ◽

2015 ◽

Vol 89 (16) ◽

pp. 8130-8151 ◽

Cited By ~ 18

Author(s):

Katie M. Kilgore ◽

Megan K. Murphy ◽

Samantha L. Burton ◽

Katherine S. Wetzel ◽

S. Abigail Smith ◽

...

Keyword(s):

Simian Immunodeficiency Virus ◽

Nonhuman Primate ◽

Neutralizing Antibodies ◽

Rhesus Macaques ◽

Neutralizing Antibody ◽

Cd40 Ligand ◽

Antibody Activity ◽

Immunodeficiency Virus ◽

Antibody Profile ◽

Hiv 1

ABSTRACTAntibodies that can neutralize diverse viral strains are likely to be an important component of a protective human immunodeficiency virus type 1 (HIV-1) vaccine. To this end, preclinical simian immunodeficiency virus (SIV)-based nonhuman primate immunization regimens have been designed to evaluate and enhance antibody-mediated protection. However, these trials often rely on a limited selection of SIV strains with extreme neutralization phenotypes to assess vaccine-elicited antibody activity. To mirror the viral panels used to assess HIV-1 antibody breadth, we created and characterized a novel panel of 14 genetically and phenotypically diverse SIVsm envelope (Env) glycoproteins. To assess the utility of this panel, we characterized the neutralizing activity elicited by four SIVmac239 envelope-expressing DNA/modified vaccinia virus Ankara vector- and protein-based vaccination regimens that included the immunomodulatory adjuvants granulocyte-macrophage colony-stimulating factor, Toll-like receptor (TLR) ligands, and CD40 ligand. The SIVsm Env panel exhibited a spectrum of neutralization sensitivity to SIV-infected plasma pools and monoclonal antibodies, allowing categorization into three tiers. Pooled sera from 91 rhesus macaques immunized in the four trials consistently neutralized only the highly sensitive tier 1a SIVsm Envs, regardless of the immunization regimen. The inability of vaccine-mediated antibodies to neutralize the moderately resistant tier 1b and tier 2 SIVsm Envs defined here suggests that those antibodies were directed toward epitopes that are not accessible on most SIVsm Envs. To achieve a broader and more effective neutralization profile in preclinical vaccine studies that is relevant to known features of HIV-1 neutralization, more emphasis should be placed on optimizing the Env immunogen, as the neutralization profile achieved by the addition of adjuvants does not appear to supersede the neutralizing antibody profile determined by the immunogen.IMPORTANCEMany in the HIV/AIDS vaccine field believe that the ability to elicit broadly neutralizing antibodies capable of blocking genetically diverse HIV-1 variants is a critical component of a protective vaccine. Various SIV-based nonhuman primate vaccine studies have investigated ways to improve antibody-mediated protection against a heterologous SIV challenge, including administering adjuvants that might stimulate a greater neutralization breadth. Using a novel SIV neutralization panel and samples from four rhesus macaque vaccine trials designed for cross comparison, we show that different regimens expressing the same SIV envelope immunogen consistently elicit antibodies that neutralize only the very sensitive tier 1a SIV variants. The results argue that the neutralizing antibody profile elicited by a vaccine is primarily determined by the envelope immunogen and is not substantially broadened by including adjuvants, resulting in the conclusion that the envelope immunogen itself should be the primary consideration in efforts to elicit antibodies with greater neutralization breadth.

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Perforin Expression in the Gastrointestinal Mucosa Is Limited to Acute Simian Immunodeficiency Virus Infection

Journal of Virology ◽

10.1128/jvi.80.6.3083-3087.2006 ◽

2006 ◽

Vol 80 (6) ◽

pp. 3083-3087 ◽

Cited By ~ 21

Author(s):

Máire F. Quigley ◽

Kristina Abel ◽

Bartek Zuber ◽

Christopher J. Miller ◽

Johan K. Sandberg ◽

...

Keyword(s):

T Cells ◽

Simian Immunodeficiency Virus ◽

Cd8 T Cells ◽

Positive Response ◽

Rhesus Macaques ◽

Gastrointestinal Mucosa ◽

Immunodeficiency Virus ◽

Siv Infection ◽

Perforin Expression ◽

Important Site

ABSTRACT Perforin-mediated cytotoxicity is a major effector function of virus-specific CD8 T cells. We have investigated the expression of perforin in the gut, an important site of simian immunodeficiency virus (SIV) pathogenesis, during experimental SIV infection of rhesus macaques. We observed significant increases in perforin protein and mRNA expression levels in the colons of SIV-infected macaques as early as 21 days after infection. However, during chronic infection, despite ongoing viral replication, perforin expression returned to levels similar to those detected in SIV-naïve animals. These findings demonstrate the presence of a robust perforin-positive response in gastrointestinal CD8 T cells during acute, but not chronic, SIV infection.

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