Douglas F Nixon

George Washington University, Washington, Washington, D.C., United States

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Publications (239)1395.48 Total impact

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    ABSTRACT: Association of HIV-1-specific T cell responses to infection risk in seronegative individuals is controversial. We quantified and phenotypically characterized gp120-specific T cell responses in HIV-1-exposed but uninfected subjects enrolled in the global Preexposure Prophylaxis Initiative (iPrEx) chemoprophylaxis trial. IFNγ ELISpot responses were detected in 24% of subjects irrespective of infection outcome. HIV-1 gp120 Envelope-specific T cell responses were more uniformly IFN-γ+TNF-α+Mip-1β+ in persistently seronegative subjects relative to subjects who later seroconverted (median frequency of 76.5% and 66.5%, respectively). IFNγ responses targeted the V2 loop for subjects who remained seronegative. HIV-1 gp120 Envelope V2 loop specific CD8+ T cell responses may help to protect against HIV-1 acquisition.
    No preview · Article · Dec 2015 · JAIDS Journal of Acquired Immune Deficiency Syndromes
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    ABSTRACT: We leveraged the global iPrEx pre-exposure chemprophylaxis trial to compare T cell activation between those who remained HIV-1 seronegative and those who became infected during the trial. The frequency of CD38+HLA-DR+ CD8+ T cells was greater in those who seroconverted relative to those that remained uninfected (1.30% vs. 0.82%, respectively, p=0.005). This translated to an association between CD8+ T cell activation and infection with an odds ratio=4.26 [95% CI 1.54, 11.78]. T cell activation may be a biomarker for elevated HIV-1 infection risk. © The Author 2015. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail:
    No preview · Article · Aug 2015 · The Journal of Infectious Diseases
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    ABSTRACT: HIV-1-specific T-cell responses in exposed seronegative subjects suggest that a viral breach of the exposure site is more common than current transmission rates would suggest and that host immunity can extinguish subsequent infection foci. The Preexposure Prophylaxis Initiative (iPrEx) chemoprophylaxis trial provided an opportunity to rigorously investigate these responses in a case-control immunology study; 84 preinfection peripheral blood mononuclear cell samples from individuals enrolled in the iPrEx trial who later seroconverted were matched with 480 samples from enrolled subjects who remained seronegative from both the placebo and active treatment arms. T-cell responses to HIV-1 Gag, Protease, Integrase, Reverse Transcriptase, Vif, and Nef antigens were quantified for all subjects in an IFN-γ enzyme-linked immunospot (ELISpot) assay. IFN-γ responses varied in magnitude and frequency across subjects. A positive response was more prevalent in those who remained persistently HIV-1-negative for Gag (P = 0.007), Integrase (P < 0.001), Vif (P < 0.001), and Nef (P < 0.001). When correlated with outcomes in the iPrEx trial, Vif- and Integrase-specific T-cell responses were associated with reduced HIV-1 infection risk [hazard ratio (HR) = 0.36, 95% confidence interval (95% CI) = 0.19-0.66 and HR = 0.52, 95% CI = 0.28-0.96, respectively]. Antigen-specific responses were independent of emtricitabine/tenofovir disoproxil fumarate use. IFN-γ secretion in the ELISpot was confirmed using multiparametric flow cytometry and largely attributed to effector memory CD4+ or CD8+ T cells. Our results show that HIV-1-specific T-cell immunity can be detected in exposed but uninfected individuals and that these T-cell responses can differentiate individuals according to infection outcomes.
    Full-text · Article · Jun 2015
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    ABSTRACT: DNA vaccines have failed to induce satisfactory immune responses in humans. Several mechanisms of double-stranded DNA sensing have been described, and modulate DNA vaccine immunogenicity at many levels. We hypothesized that the immunogenicity of DNA vaccines in humans is suppressed by APOBEC-mediated plasmid degradation. We showed that plasmid sensing via STING and TBK-1 leads to IFN-β induction, which results in APOBEC3A mRNA upregulation through a mechanism involving PKC signaling. We also showed that murine APOBEC2 expression in HEK293T cells led to 10-fold reduction in intracellular plasmid levels and plasmid-encoded mRNA, and 2.6-fold reduction in GFP-expressing cells. A bicistronic DNA vaccine expressing an immunogen and an APOBEC2-specific shRNA efficiently silenced APOBEC2 both in vitro and in vivo, increasing the frequency of induced IFN-γ-secreting T cells. Our study brings new insights into the intracellular machinery involved in double-stranded DNA sensing and how to modulate it to improve DNA vaccine immunogenicity in humans.Immunology and Cell Biology accepted article preview online, 08 May 2015. doi:10.1038/icb.2015.53.
    Full-text · Article · May 2015 · Immunology and Cell Biology
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    ABSTRACT: CD8+ T cells are important for HIV-1 virus control, but are also a major contributing factor that drives HIV-1 virus sequence evolution. Although HIV-1 cytotoxic T cell (CTL) escape mutations are a common aspect during HIV-1 infection, less is known about the importance of T cell pressure in reversing HIV-1 virus back to a consensus sequences. In this study we aimed to assess the frequency with which reversion of transmitted mutations in T cell epitopes were associated with T cell responses to the mutation. This study included 14 HIV-1 transmission pairs consisting of a 'source' (virus-donor) and a 'recipient' (newly infected individual). Non-consensus B sequence amino acids (mutations) in T cell epitopes in HIV-1 gag regions p17, p24, p2 and p7 were identified in each pair and transmission of mutations to the recipient was verified with population viral sequencing. Longitudinal analyses of the recipient's viral sequence were used to identify whether reversion of mutations back to the consensus B sequence occurred. Autologous 12-mer peptides overlapping by 11 were synthesized, representing the sequence region surrounding each reversion and longitudinal analysis of T cell responses to source-derived mutated and reverted epitopes were assessed. We demonstrated that mutations in the source were frequently transmitted to the new host and on an average 17 percent of mutated epitopes reverted to consensus sequence in the recipient. T cell responses to these mutated epitopes were detected in 7 of the 14 recipients in whom reversion occurred. Overall, these findings indicate that transmitted non-consensus B epitopes are frequently immunogenic in HLA-mismatched recipients and new T cell pressures to T cell escape mutations following transmission play a significant role in maintaining consensus HIV-1 sequences.
    Full-text · Article · Apr 2015 · PLoS ONE
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    ABSTRACT: Background Psoriasis patients have relatively infrequent cutaneous viral infections compared to atopic dermatitis patients. Increased expression of four antiviral proteins (MX1, BST2, ISG15 and OAS2) has been reported in psoriatic skin and genetic studies of psoriasis have identified susceptibility genes in antiviral pathways.Objective To determine if psoriasis is associated with pervasive expression of antiviral genes in skin and blood.Methods We performed RNA sequencing on skin samples of 18 subjects with chronic plaque psoriasis and 16 healthy controls. We examined the expression of a predefined set of 42 antiviral genes, each of which has been shown in previous studies to inhibit viral replication. In parallel, we examined antiviral gene expression in atopic dermatitis, non-lesional psoriatic skin and psoriatic blood. We performed HIV-1 infectivity assays in CD4+ peripheral blood T cells from psoriatic and healthy individuals.ResultsWe observed significant overexpression of 16 antiviral genes in lesional psoriatic skin, with a greater than two-fold increase in ISG15, RSAD2, IRF7, MX2 and TRIM22 (P < 1E-07). None of these genes was overexpressed in atopic dermatitis skin (P < 0.0001) or non-lesional psoriatic skin. In contrast to the skin compartment, no differences in antiviral gene expression were detected in the peripheral blood of psoriasis cases compared to healthy controls. CD4+ T cells from both psoriatic and healthy patients supported HIV-1 infection at a similar rate.Conclusion Our findings highlight psoriasis as an inflammatory disease with cutaneous but not systemic immune activation against viral pathogens.
    No preview · Article · Mar 2015 · Journal of the European Academy of Dermatology and Venereology
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    Fabio E Leal · Marcin Michniowski · Douglas Nixon
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    ABSTRACT: HTLV-1, the first human retrovirus described, is the causative agent of a neglected disease affecting 5 - 10 million people worldwide. While often considered a lifelong asymptomatic disease, neurological complications including progressive neurodegeneration and an aggressive adult T-cell leukemia (ATL), which can arise in up to 10% of HTLV-1-infected individuals. The mode of transmission for this retrovirus is through blood or sexual contact, and mother-to-child-transmission (MTCT) occurs in approximately 20% of infants breastfed for 6 months or more. However, the advantages of breastfeeding over formula feeding to prevent overall child morbidity and mortality have been well established, especially in developing countries. This creates a paradox, whereby refrainment of breastfeeding to prevent HTLV-1 transmission has been effective in a developed country such as Japan, but is inappropriate for developing countries with higher infant morbidity and mortality. In HIV-1 infection, maternal and infant antiretroviral therapy (ART) is one of the most important measures to prevent HIV-1 MTCT. If ART was used to prevent post partum HTLV-1 infection of neonates through breast milk feeding, HTLV-1 transmission could be halted. However, prevention of vertical HTLV-1 infection is not part of routine health care practice. Interestingly, studies demonstrate the capacity of AZT to significantly inhibit HTLV-1 infection of lymphocytes in vitro. We suggest that in areas of high prevalence of HTLV-1 infection, formal guidelines be adopted to screen pregnant women for HTLV-1 and a trial performed to assess the therapeutic benefit of ART for women during delivery, and for the infant for the duration of breastfeeding, to prevent HTLV-1 transmission. A way to stop HTLV-1 vertical transmission should be pursued and offered to mothers and children in areas of high HTLV-1 prevalence around the globe.
    Preview · Article · Oct 2014
  • Douglas F Nixon · Gary L Simon · Rui Andre Saraiva Raposo

    No preview · Article · Oct 2014 · JAIDS Journal of Acquired Immune Deficiency Syndromes
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    ABSTRACT: Memory stem T cells (TSCM) constitute a long-lived, self-renewing lymphocyte population essential for the maintenance of functional immunity. The hallmarks of HIV-1 pathogenesis are CD4+ T cell depletion and abnormal cellular activation. We investigated the impact of HIV-1 infection on the TSCM compartment, as well as any protective role these cells may have in disease progression, by characterizing this subset in a cohort of 113 subjects with various degrees of viral control on and off highly active antiretroviral therapy (HAART). We observed that the frequency of CD8+ TSCM was decreased in all individuals with chronic, untreated HIV-1 infection and that HAART had a restorative effect on this subset. In contrast, natural controllers of HIV-1 had the highest absolute number of CD4+ TSCM cells among all of the infected groups. The frequency of CD4+ TSCM predicted higher CD8+ TSCM frequencies, consistent with a role for the CD4+ subset in helping to maintain CD8+ memory T cells. In addition, TSCM appeared to be progenitors for effector T cells (TEM), as these two compartments were inversely correlated. Increased frequencies of CD8+ TSCM predicted lower viral loads, higher CD4+ counts, and less CD8+ T cell activation. Finally, we found that TSCM express the mucosal homing integrin α4β7 and can be identified in gut-associated lymphoid tissue (GALT). The frequency of mucosal CD4+ TSCM was inversely correlated with that in the blood, potentially reflecting the ability of these self-renewing cells to migrate to a crucial site of ongoing viral replication and CD4+ T cell depletion.
    Full-text · Article · Sep 2014 · Journal of Virology
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    ABSTRACT: Background Psoriasis is a multifactorial, chronic disease of skin affecting 2-3 % of the world¿s population. Genetic studies of psoriasis have identified a number of susceptibility genes that are involved in anti-viral immunity. Furthermore, physiological studies have also found an increase in anti-viral proteins in psoriatic skin. These findings suggest the presence of an anti-viral state in psoriatic skin. However, the triggers for this anti-viral cascade and its consequences for host immunity are not known. Endogenous retroviruses have previously been described in many autoimmune diseases including psoriasis.Methods In the present study we examined the humoral immune response against human endogenous retrovirus-K (HERV-K) proteins and the cutaneous expression levels of multiple HERV-K genes in psoriasis patients and healthy controls.ResultsIn psoriatic sera we observed a significant decrease in IgM response against three HERV-K proteins: Env surface unit (SU), Env transmembrane protein (TM), and Gag capsid (CA) in comparison to sera obtained from blood bank healthy controls. A decrease in IgG response was also observed against CA. Furthermore, using quantitative RT-PCR we observed a decrease in the expression of HERV-K Env, Gag, Pol and Rec as well as ERV-9 genes in lesional psoriatic skin as compared to healthy skin.Conclusions Together, our results suggest that the pro-inflammatory, anti-viral state in psoriasis is associated with diminished expression of HERV-K gene transcripts and a concomitant decrease in humoral responses to HERV-K. Our results indicate that a simple model where continuous, minimally changing HERV-K expression serves as an antigenic trigger in psoriasis might not be correct and further studies are needed to decipher the possible relationship between psoriasis and HERVs.
    Full-text · Article · Sep 2014 · Journal of Translational Medicine
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    ABSTRACT: In this study, we investigated the expression levels of host restriction factors in six untreated HIV-1-positive patients over the course of infection. We found that the host restriction factor gene expression profile consistently increased over time and was significantly associated with CD4+ T cell activation and viral load. Our data are among the first to demonstrate the dynamic nature of host restriction factors in vivo over time.
    Preview · Article · Jul 2014 · Journal of Virology
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    ABSTRACT: The failure of antiviral vaccines is often associated with rapid viral escape from specific immune responses. In the past, conserved epitope or algorithmic epitope selections, such as mosaic vaccines, have been designed to diversify immunity and to circumvent potential viral escape. An alternative approach is to identify conserved stable non-HIV-1 self-epitopes present exclusively in HIV-1-infected cells. We showed previously that human endogenous retroviral (HERV) mRNA transcripts and protein are found in cells of HIV-1-infected patients and that HERV-K (HML-2)-specific T cells can eliminate HIV-1-infected cells in vitro. In this article, we demonstrate that a human anti-HERV-K (HML-2) transmembrane protein Ab binds specifically to HIV-1-infected cells and eliminates them through an Ab-dependent cellular cytotoxicity mechanism in vitro. Thus, Abs directed against epitopes other than HIV-1 proteins may have a role in eliminating HIV-1-infected cells and could be targeted in novel vaccine approaches or immunotherapeutic modalities.
    Full-text · Article · Jul 2014 · The Journal of Immunology

  • No preview · Article · May 2014 · Journal of alternative and complementary medicine (New York, N.Y.)

  • No preview · Conference Paper · May 2014
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    ABSTRACT: Chronic stress has deleterious effects on immune function, which can lead to adverse health outcomes. However, studies investigating the impact of stress reduction interventions on immunity in clinical research have yielded divergent results, potentially stemming from differences in study design and genetic heterogeneity, among other clinical research challenges. To test the hypothesis that reducing glucocorticoid levels enhances certain immune functions, we administered influenza vaccine once (prime) or twice (boost) to mice housed in either standard control caging or environmental enrichment (EE) caging, an approach we have shown reduces mouse corticosterone production. Compared with controls, EE mice had significantly lower levels of fecal corticosterone metabolites (FCM) and increased splenic B and T lymphocyte numbers. Corticosterone levels were negatively associated with the numbers of CD19(+) (r(2)=0.43, p=0.0017), CD4(+), (r(2)=0.28, p=0.0154) and CD8(+) cells (r(2)=0.20, p=0.0503). Vaccinated mice showed non-significant differences in IgG titer between caging groups, although EE mice tended to exhibit larger increases in titer from prime to boost than controls; the interaction between caging group (control vs. EE) and vaccine group (prime vs. boost) showed a strong statistical trend (Cage-Group*Vaccine-Group, F=4.27, p=0.0555), suggesting that there may be distinct effects of EE caging on primary versus secondary IgG vaccine responses. Vaccine-stimulated splenocytes from boosted EE mice had a significantly greater frequency of IL-5 secreting cells than boosted controls (Meandiff 67.7 IL-5 SFU/10(6) splenocytes, CI95 0.24 to 135.1, p=0.0493), and showed a greater increase in the frequency of IL-5 secreting cells from prime to boost. Our results suggest that corticosterone reduction via EE caging was associated with enhanced secondary vaccine responses, but had little effect on primary responses in mice. These findings help identify differences in primary and secondary vaccine responses in relationship to stress mediators that may be relevant in clinical studies.
    Full-text · Article · Mar 2014 · Molecular Medicine
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    ABSTRACT: The enormous sequence diversity of HIV remains a major roadblock to the development of a prophylactic vaccine and new approaches to induce protective immunity are needed. Endogenous retrotransposable elements (ERE) such as endogenous retrovirus K (ERV)-K and long interspersed nuclear element-1 (LINE-1) are activated during HIV-1-infection and could represent stable, surrogate targets to eliminate HIV-1-infected cells. Here, we explored the hypothesis that vaccination against ERE would protect macaques from acquisition and replication of simian immunodeficiency virus (SIV). Following vaccination with antigens derived from LINE-1 and ERV-K consensus sequences, animals mounted immune responses that failed to delay acquisition of SIVsmE660. We observed no differences in acute or set point viral loads between ERE-vaccinated and control animals suggesting that ERE-specific responses were not protective. Indeed, ERE-specific T cells failed to expand anamnestically in vivo following infection with SIVsmE660 and did not recognize SIV-infected targets in vitro, in agreement with no significant induction of targeted ERE mRNA by SIV in macaque CD4+ T cells. Instead, lower infection rates and viral loads correlated significantly to protective TRIM5α alleles. Cumulatively, these data demonstrate that vaccination against the selected ERE consensus sequences in macaques did not lead to immune-mediated recognition and killing of SIV-infected cells, as has been shown for HIV-infected human cells using patient-derived HERV-K-specific T cells. Thus, further research is required to identify the specific nonhuman primate EREs and retroviruses that recapitulate the activity of HIV-1 in human cells. These results also highlight the complexity in translating observations of the interplay between HIV-1 and human EREs to animal models.
    Full-text · Article · Mar 2014 · PLoS ONE
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    ABSTRACT: Invariant natural killer T (iNKT) cells are CD1d-restricted immunoregulatory lymphocytes that share characteristics of both the innate and adaptive immune systems. Although it has been reported that iNKT cells are present in the human fetal thymus, it is currently unknown how they distribute, differentiate, and function in fetal peripheral lymphoid and non-lymphoid organs. Here, we show that functional human fetal iNKT cells develop and differentiate in a tissue-specific manner during the second trimester. Fetal iNKT cells accumulated in the small intestine, where they gained a mature phenotype and mounted robust interferon (IFN)-γ responses. In contrast, iNKT cells in the spleen and mesenteric lymph nodes were less frequently detected, less differentiated, mounted poor IFN-γ responses, but proliferated vigorously upon stimulation with α-galactosylceramide. These data demonstrate that fetal iNKT cells can differentiate and acquire potent effector functions in utero before the establishment of the commensal microflora.Mucosal Immunology advance online publication, 19 March 2014; doi:10.1038/mi.2014.13.
    No preview · Article · Mar 2014 · Mucosal Immunology
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    ABSTRACT: Human Endogenous Retroviruses (HERVs) comprise about 8% of the human genome and have lost their ability to replicate or to produce infectious particles after having accumulated mutations over time. We assessed the kinetics of expression of HERV-K (HML-2) Envelope mRNA transcript and surface unit (SU) and transmembrane (TM) subunit proteins during HIV-1 infection. We also mapped the specificity of the humoral response to HERV-K (HML-2) Envelope protein in HIV-1 infected subjects at different stages of disease, and correlated the response with plasma viral load. We found that HIV-1 modified HERV-K (HML-2) Env mRNA expression, resulting in the expression of a fully N-glycosylated HERV-K (HML-2) envelope protein on the cell surface. Serological mapping of HERV-K (HML-2) envelope protein linear epitopes revealed two major immunogenic domains, one on SU and another on the ectodomain of TM. The titers of HERV-K (HML-2) TM antibodies were dramatically increased in HIV-1 infected subjects (p < 0.0001). HIV-1 infected adults who control HIV-1 in the absence of therapy ("elite" controllers) had a higher titer response against TM compared to antiretroviral-treated adults (p < 0.0001) and uninfected adults (p < 0.0001). These data collectively suggest that HIV-1 infection induces fully glycosylated HERV-K (HML-2) envelope TM protein to which antibodies are induced. These anti-HERV-K (HML-2) TM antibodies are a potential marker of HIV-1 infection, and are at higher titer in elite controllers. HERV-K (HML-2) envelope TM protein may be a new therapeutic target in HIV-1 infection.
    Full-text · Article · Jan 2014 · Retrovirology
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    Edwin Leeansyah · Liyen Loh · Douglas F Nixon · Johan K Sandberg
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    ABSTRACT: Innate-like, evolutionarily conserved MR1-restricted mucosa-associated invariant T (MAIT) cells represent a large antimicrobial T-cell subset in humans. Here, we investigate the development of these cells in second trimester human fetal tissues. MAIT cells are rare and immature in the fetal thymus, spleen and mesenteric lymph nodes. In contrast, mature IL-18Rα(+) CD8αα MAIT cells are enriched in the fetal small intestine, liver and lung. Independently of localization, MAIT cells express CD127 and Ki67 in vivo and readily proliferate in response to Escherichia coli in vitro. Maturation is accompanied by the gradual post-thymic acquisition of the PLZF transcription factor and the ability to produce IFNγ and IL-22 in response to bacteria in mucosa. Thus, MAIT cells acquire innate-like antimicrobial responsiveness in mucosa before exposure to environmental microbes and the commensal microflora. Establishment of this arm of immunity before birth may help protect the newborn from a range of pathogenic microbes.
    Full-text · Article · Jan 2014 · Nature Communications
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    ABSTRACT: The ability to reconstitute a normal immune system with antiretroviral therapy in the setting of HIV infection remains uncertain. This study aimed to characterize quantitative and qualitative aspects of various T cell subpopulations that do not improve despite effective ART. CD4∶CD8 ratio was evaluated in HIV-infected subjects with viral loads >10,000 copies/µl ("non-controllers", n = 42), those with undetectable viral loads on ART ("ART-suppressed", n = 53), and HIV-uninfected subjects (n = 22). In addition, T cell phenotype and function were examined in 25 non-controllers, 18 ART-suppressed, and 7 HIV-uninfected subjects. CD4∶CD8 ratio in non-controllers, ART-suppressed, and HIV-uninfected subjects was 0.25, 0.48, and 1.95 respectively (P<0.0001 for all comparisons). The increased ratio in ART-suppressed compared to non-controllers was driven by an increase of CD4+ T cells, with no change in the expanded CD8+ T cell population. Expansion of differentiated (CD28-CD27-CD45RA+/-CCR7-) T cell subpopulations persisted despite ART and minimal changes were noted in naïve T cell frequencies over time. Increased number of CD8+CD28- T cells and increased CD8+ CMV-specific T cell responses were associated with a decreased CD4∶CD8 ratio. Measures of T cell function demonstrated persistence of high frequencies of CD8+ T cells producing IFN-γ. Lastly, though all CD8+ subpopulations demonstrated significantly lower Ki67 expression in ART-suppressed subjects, CD4+ T cell subpopulations did not consistently show this decrease, thus demonstrating different proliferative responses in the setting of T cell depletion. In summary, this study demonstrated that CD4∶CD8 ratios remained significantly decreased and naïve T cell numbers were slow to increase despite long-term viral suppression on ART. In addition, there is a evidence of differential regulation of the CD4+ and CD8+ T cell subpopulations, suggesting independent homeostatic regulation of the two compartments.
    Full-text · Article · Jan 2014 · PLoS ONE

Publication Stats

13k Citations
1,395.48 Total Impact Points


  • 2013-2015
    • George Washington University
      • Department of Microbiology, Immunology, and Tropical Medicine
      Washington, Washington, D.C., United States
  • 2001-2015
    • University of California, San Francisco
      • • Department of Medicine
      • • Division of Experimental Medicine
      • • Department of Epidemiology and Biostatistics
      • • Gladstone Institute
      San Francisco, California, United States
  • 2011
    • University of Washington Seattle
      Seattle, Washington, United States
  • 2009
    • Universidade Federal de São Paulo
      San Paulo, São Paulo, Brazil
  • 2008
    • CSU Mentor
      • Department of Medicine
      Long Beach, California, United States
  • 2006
    • Institute of Human Virology
      Maryland City, Maryland, United States
  • 2002-2006
    • J. David Gladstone Institutes
      San Francisco, California, United States
  • 2001-2006
    • The Rockefeller University
      • Laboratory of Cellular Physiology and Immunology
      New York City, New York, United States
  • 2005
    • University of Oslo
      Kristiania (historical), Oslo, Norway
  • 2003
    • Karolinska Institutet
      Solna, Stockholm, Sweden
  • 1991-2001
    • Oxford University Hospitals NHS Trust
      • Nuffield Department of Medicine
      Oxford, England, United Kingdom
  • 1998
    • University of Oxford
      Oxford, England, United Kingdom
  • 1996-1997
    • United Biomedical, Inc.
      Hauppauge, New York, United States
  • 1990
    • IHU de Strasbourg
      Strasburg, Alsace, France