Jack T Stapleton

University of Iowa, Iowa City, Iowa, United States

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Publications (161)1098.28 Total impact

  • Jingyang Zhang · Ying Zhang · Kathryn Chaloner · Jack T Stapleton ·
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    ABSTRACT: In many medical applications, combining information from multiple biomarkers could yield a better diagnosis than any single one on its own. When there is a lack of a gold standard, an algorithm of classifying subjects into the case and non-case status is necessary for combining multiple markers. The aim of this paper is to develop a method to construct a composite test from multiple applicable tests and derive an optimal classification rule under the absence of a gold standard. Rather than combining the tests, we treat the tests as a sequence. This sequential composite test is based on a mixture of two multivariate normal latent models for the distribution of the test results in case and non-case groups, and the optimal classification rule is derived returning the greatest sensitivity at a given specificity. This method is applied to a real-data example and simulation studies have been carried out to assess the statistical properties and predictive accuracy of the proposed composite test. This method is also attainable to implement nonparametrically. Copyright © 2015 John Wiley & Sons, Ltd.
    Statistics in Medicine 11/2015; DOI:10.1002/sim.6780 · 1.83 Impact Factor
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    ABSTRACT: Smoking is associated with poorer health outcomes for both African and European Americans. In order to better understand whether ethnic-specific genetic variation may underlie some of these differences, we compared the smoking-associated genome-wide methylation signatures of African Americans with those of European Americans, and followed up this analysis with a focused examination of the most ethnically divergent locus, cg19859270, at the GPR15 gene. We examined the association of methylation at this locus to the rs2230344 SNP and GPR15 gene and protein expression. Consistent with prior analyses, AHRR residue cg05575921 was the most differentially methylated residue in both African Americans and European Americans. However, the second most differentially methylated locus in African Americans, cg19859270, was only modestly differentially methylated in European Americans. Interrogation of the methylation status of this CpG residue found in GPR15, a chemokine receptor involved in HIV pathogenesis, showed a significant interaction of ethnicity with smoking as well as a marginal effect of genotype at rs2230344, a neighboring non-synonymous SNP, but only among African Americans. Gene and protein expression analyses showed that demethylation at cg19859270 was associated with an increase in both mRNA and protein levels. Since GPR15 is involved in the early stages of viral replication for some HIV-1 and HIV-2 isolates, and the prevalence of HIV is increased in African Americans and smokers, these data support a possible role for GPR15 in the ethnically dependent differential prevalence of HIV.
    Frontiers in Psychiatry 10/2015; 6:132. DOI:10.3389/fpsyt.2015.00132
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    ABSTRACT: T cell receptor (TCR) signaling is required for T-cell activation, proliferation, differentiation, and effector function. Hepatitis C virus (HCV) infection is associated with impaired T-cell function leading to persistent viremia, delayed and inconsistent antibody responses, and mild immune dysfunction. Although multiple factors appear to contribute to T-cell dysfunction, a role for HCV particles in this process has not been identified. Here, we show that incubation of primary human CD4+ and CD8+ T-cells with HCV RNA-containing serum, HCV-RNA containing extracellular vesicles (EVs), cell culture derived HCV particles (HCVcc) and HCV envelope pseudotyped retrovirus particles (HCVpp) inhibited TCR-mediated signaling. Since HCVpp’s contain only E1 and E2, we examined the effect of HCV E2 on TCR signaling pathways. HCV E2 expression recapitulated HCV particle-induced TCR inhibition. A highly conserved, 51 nucleotide (nt) RNA sequence was sufficient to inhibit TCR signaling. Cells expressing the HCV E2 coding RNA contained a short, virus-derived RNA predicted to be a Dicer substrate, which targeted a phosphatase involved in Src-kinase signaling (PTPRE). T-cells and hepatocytes containing HCV E2 RNA had reduced PTPRE protein levels. Mutation of 6 nts abolished the predicted Dicer interactions and restored PTPRE expression and proximal TCR signaling. HCV RNA did not inhibit distal TCR signaling induced by PMA and Ionomycin; however, HCV E2 protein inhibited distal TCR signaling. This inhibition required lymphocyte-specific tyrosine kinase (Lck). Lck phosphorylated HCV E2 at a conserved tyrosine (Y613), and phospho-E2 inhibited nuclear translocation of NFAT. Mutation of Y613 restored distal TCR signaling, even in the context of HCVpps. Thus, HCV particles delivered viral RNA and E2 protein to T-cells, and these inhibited proximal and distal TCR signaling respectively. These effects of HCV particles likely aid in establishing infection and contribute to viral persistence.
    PLoS Pathogens 09/2015; 11(9):e1005183. DOI:10.1371/journal.ppat.1005183 · 7.56 Impact Factor
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    ABSTRACT: Human Pegivirus (HPgV, formally GB virus C) infects lymphocytes and NK cells in vivo, and infection is associated with reduced T cell and NK cell activation in HIV-infected individuals. The mechanism by which HPgV inhibits NK cell activation has not been assessed. Following IL-12 stimulation, IFNγ expression was lower in HIV-HPgV co-infected subjects compared to HIV mono-infected subjects (p=0.02). In addition, HPgV positive human sera, extracellular vesicles containing E2 protein, recombinant E2 protein and synthetic E2 peptides containing a predicted Tyk2 interacting motif inhibited NK cell IL-12-mediated IFNγ release. E2 protein also inhibited Tyk2 activation following IL-12 stimulation. In contrast, cytolytic NK cell function was not altered by HPgV. Inhibition of NK cell-induced proinflammatory/antiviral cytokines may contribute to both HPgV persistence and reduced immune activation during HIV-coinfection. Understanding mechanisms by which HPgV alters immune activation may contribute towards novel immunomodulatory therapies to treat HIV and inflammatory diseases. Published by Elsevier Inc.
    Virology 07/2015; 485:116-127. DOI:10.1016/j.virol.2015.07.008 · 3.32 Impact Factor
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    ABSTRACT: Modified vaccinia Ankara (MVA) is being developed as a safer smallpox vaccine and is being placed in the US Strategic National Stockpile (SNS) as a liquid formulation for subcutaneous (SC) administration at a dose of 1×10(8) TCID50 in a volume of 0.5mL. This study compared the safety and immunogenicity of the standard formulation, dose and route with both a more stable, lyophilized formulation and with an antigen-sparing intradermal (ID) route of administration. 524 subjects were randomized to receive either a full dose of Lyophilized-SC, a full dose of Liquid-SC or 20% (2×10(7) TCID50 in 0.1mL) of a full dose Liquid-ID MVA on Days 0 and 28. Safety and immunogenicity were followed through 180 days post second vaccination. Among the 3 groups, the proportion of subjects with moderate/severe functional local reactions was significantly different (P=0.0013) between the Lyophilized-SC group (30.3%), the Liquid-SC group (13.8%) and Liquid-ID group (22.0%) only after first vaccination; and for moderate/severe measured erythema and/or induration after any vaccination (P=0.0001) between the Lyophilized-SC group (58.2%), the Liquid-SC group (58.1%) and the Liquid-ID group (94.8%) and the reactions lasted longer in the Liquid-ID group. In the ID Group, 36.1% of subjects had mild injection site skin discoloration lasting ≥6 months. After second vaccination, geometric mean neutralization titers were 77.6, 45.2 and 54.4 for the Lyophilized-SC, Liquid-SC and Liquid-ID groups, respectively, and the maximum number of responders in each group was 100/145 (69.0%), 70/148 (47.3%) and 82/146 (56.2%), respectively. At 180 days after the second vaccination, geometric mean neutralization titers declined to 11.7, 10.2 and 10.4 with only 54.3%, 39.2% and 35.2% of subjects remaining seropositive for the Lyophilized-SC, Liquid-SC and Liquid-ID groups, respectively. Both the Lyophilized-SC and Liquid-ID groups were considered non-inferior (primary objective) to the Liquid-SC group. Transitioning to a lyophilized formulation, which has a longer shelf life, will not negatively impact immunogenicity. In a situation where insufficient vaccine is available, ID vaccination could be used, increasing the number of available doses of vaccine in the SNS 5-fold (i.e., from 20 million to 100 million doses). Copyright © 2015. Published by Elsevier Ltd.
    Vaccine 07/2015; 33(39). DOI:10.1016/j.vaccine.2015.06.075 · 3.62 Impact Factor
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    ABSTRACT: This query of North American infectious diseases (ID) physicians reviews current and anticipated practice patterns related to HCV care. Fewer than 20% of survey respondents evaluated and/or treated >10 HCV-infected individuals in the past year. We review HCV practice patterns, barriers to management, and education among ID physicians. © 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: journals.permissions@oup.com.
    Clinical Infectious Diseases 05/2015; 61(5). DOI:10.1093/cid/civ384 · 8.89 Impact Factor
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    ABSTRACT: Background. First- and second-generation smallpox vaccines are contraindicated in individuals infected with human immunodeficiency virus (HIV). A new smallpox vaccine is needed to protect this population in the context of biodefense preparedness. The focus of this study was to compare the safety and immunogenicity of a replication-deficient, highly attenuated smallpox vaccine modified vaccinia Ankara (MVA) in HIV-infected and healthy subjects. Methods. An open-label, controlled Phase II trial was conducted at 36 centers in the United States and Puerto Rico for HIV-infected and healthy subjects. Subjects received 2 doses of MVA administered 4 weeks apart. Safety was evaluated by assessment of adverse events, focused physical exams, electrocardiogram recordings, and safety laboratories. Immune responses were assessed using enzyme-linked immunosorbent assay (ELISA) and a plaque reduction neutralization test (PRNT). Results. Five hundred seventy-nine subjects were vaccinated at least once and had data available for analysis. Rates of ELISA seropositivity were comparably high in vaccinia-naive healthy and HIV-infected subjects, whereas PRNT seropositivity rates were higher in healthy compared with HIV-infected subjects. Modified vaccinia Ankara was safe and well tolerated with no adverse impact on viral load or CD4 counts. There were no cases of myo-/pericarditis reported. Conclusions. Modified vaccinia Ankara was safe and immunogenic in subjects infected with HIV and represents a promising smallpox vaccine candidate for use in immunocompromised populations.
    05/2015; 2(2):ofv040-ofv040. DOI:10.1093/ofid/ofv040
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    Ernest T Chivero · Jack T Stapleton ·
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    ABSTRACT: Human Pegivirus (HPgV; originally called GB virus C/hepatitis G virus) is an RNA virus within the Pegivirus genus of the Flaviviridae that commonly causes persistent infection. Worldwide, approximately 750 million people are actively infected (viremic) and an estimated 0.75 to 1.5 billion people have evidence of prior HPgV infection. No causal association between HPgV and disease has been identified; however, several studies describe a beneficial relationship between persistent HPgV infection and survival in HIV-infected individuals. The beneficial effect appears to be related to a reduction in host immune activation. HPgV replicates well in vivo (> 1x107 genome copies detected per ml plasma); however, the virus grows poorly in vitro and systems to study this virus are limited. Consequently, mechanisms of viral persistence and host immune modulation remain poorly characterized, and the primary permissive cell type(s) has not yet been identified. HPgV RNA is found in liver, spleen, bone marrow, and peripheral blood mononuclear cells (PBMCs), including T and B lymphocytes, NK cells, and monocytes, although the mechanism of cell-to-cell transmission is unclear. HPgV RNA is also present in serum microvesicles with properties of exosomes. These microvesicles are able to transmit viral RNA to PBMCs in vitro, resulting in productive infection. This review summarizes existing data on HPgV cellular tropism, the effect of HPgV on immune activation in various PBMCs and discusses how this may influence viral persistence. We conclude that an increased understanding of HPgV replication and immune modulation may provide insights into persistent RNA viral infection of humans.
    Journal of General Virology 02/2015; 96(7). DOI:10.1099/vir.0.000086 · 3.18 Impact Factor
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    ABSTRACT: Background Although adolescent girls are the main population for prophylactic human papillomavirus (HPV) vaccines, adult women who remain at risk of cervical cancer can also be vaccinated. We report data from the interim analysis of the ongoing VIVIANE study, the aim of which is to assess the efficacy, safety, and immunogenicity of the HPV 16/18 AS04-adjuvanted vaccine in adult women. Methods In this phase 3, multinational, double-blind, randomised controlled trial, we randomly assigned healthy women older than 25 years to the HPV 16/18 vaccine or control (1:1), via an internet-based system with an algorithm process that accounted for region, age stratum, baseline HPV DNA status, HPV 16/18 serostatus, and cytology. Enrolment was age-stratified, with about 45% of participants in each of the 26–35 and 36–45 years age strata and 10% in the 46 years and older stratum. Up to 15% of women in each age stratum could have a history of HPV infection or disease. The primary endpoint was vaccine efficacy against 6-month persistent infection or cervical intraepithelial neoplasia grade 1 or higher (CIN1+) associated with HPV 16/18. The primary analysis was done in the according-to-protocol cohort for efficacy, which consists of women who received all three vaccine or control doses, had negative or low-grade cytology at baseline, and had no history of HPV disease. Secondary analyses included vaccine efficacy against non-vaccine oncogenic HPV types. Mean follow-up time was 40·3 months. This study is registered with ClinicalTrials.gov, number NCT00294047. Findings The first participant was enrolled on Feb 16, 2006, and the last study visit for the present analysis took place on Dec 10, 2010; 5752 women were included in the total vaccinated cohort (n=2881 vaccine, n=2871 control), and 4505 in the according-to-protocol cohort for efficacy (n=2264 vaccine, n=2241 control). Vaccine efficacy against HPV 16/18-related 6-month persistent infection or CIN1+ was significant in all age groups combined (81·1%, 97·7% CI 52·1–94·0), in the 26–35 years age group (83·5%, 45·0–96·8), and in the 36–45 years age group (77·2%, 2·8–96·9); no cases were seen in women aged 46 years and older. Vaccine efficacy against atypical squamous cells of undetermined significance or greater associated with HPV 16/18 was also significant. We also noted significant cross-protective vaccine efficacy against 6-month persistent infection with HPV 31 (79·1%, 97·7% CI 27·6–95·9) and HPV 45 (76·9%, 18·5–95·6]) Serious adverse events occurred in 285 (10%) of 2881 women in the vaccine group and 267 (9%) of 2871 in the control group; five (<1%) and eight (<1%) of these events, respectively, were believed to be related to vaccination. Interpretation In women older than 25 years, the HPV 16/18 vaccine is efficacious against infections and cervical abnormalities associated with the vaccine types, as well as infections with the non-vaccine HPV types 31 and 45. Funding GlaxoSmithKline Biologicals SA.
    The Lancet 12/2014; 384(9961). DOI:10.1016/S0140-6736(14)60920-X · 45.22 Impact Factor
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    ABSTRACT: Background: An association between GB virus C (GBV-C) and improved outcomes of human immunodeficiency virus (HIV) infection has been reported in HIV-positive individuals with active GBV-C coinfection. This study provides insights into the immune mechanisms underlying the protective role of GBV-C in HIV-infected patients. Methods: The concentrations of 64 cytokines and chemokines were measured in plasma samples obtained from the Viral Activation Transfusion Study cohort before transfusion and longitudinally from 30 patients positive for both HIV and GBV-C (hereafter, "cases") and 30 patients positive for HIV and negative for GBV-C (hereafter, "controls"). Results: Cases had lower HIV viral loads and higher CD4 T-cell counts than controls after acquisition of GBV-C infection. Most of the modulated cytokines and chemokines were reduced after GBV-C detection, including many proinflammatory cytokines, suggesting an overall antiinflammatory effect of GBV-C in HIV-positive subjects. Most pathways and functions of the measured cytokines were downregulated in cases, except cell death pathways, which were upregulated in various cell subsets in the 3 months after GBV-C detection. Conclusions: GBV-C has a protective effect, in part through a competition mechanism leading to decreased inflammation and improved HIV disease outcome in cases. Further studies are necessary to establish whether GBV-C may have deleterious effects on the host at the cellular level, including depleting the cells that are the targets of HIV.
    The Journal of Infectious Diseases 11/2014; 211(10). DOI:10.1093/infdis/jiu660 · 6.00 Impact Factor
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    ABSTRACT: Background: An avian H7N9 influenza outbreak has caused morbidity with high mortality in China since 2013. To compare the safety and immunogenicity of H7N9 vaccine with or without MF59 adjuvant, we conducted a phase 2 clinical trial at four NIAID-funded Vaccine and Treatment Evaluation Units (VTEUs). Methods: Healthy adults aged 19-64 years were given influenza A/Shanghai/2/13 (H7N9) inactivated virus vaccine IM on days 0 and 21 at nominal antigen (Ag) doses of 3.75, 7.5, 15, or 45µg. Field site mixing of Ag with MF59 (9.75 mg squalene/0.25ml) was performed for both, one or neither of the 2 doses. Key study outcomes were antibody (Ab) titers on d42, vaccine-related serious adverse events, and solicited local and systemic symptoms post-vaccination. B and T cells assays were performed on a subset of 37 participants. ClinicalTrials.gov # NCT01938742. Results: 700 subjects were enrolled. Hemagglutination inhibition (HAI) and neutralizing Ab (NAb) were minimal after 2 doses of unadjuvanted vaccine or 1 dose of adjuvanted vaccine (any Ag dose). For 3.75 µg + MF59, d42 HAI seroconversion (SC; 4-fold titer rise to >40) occurred in 60% (95% CI, 50-70); and geometric mean titer (GMT) was 35 (95% CI, 26-47). Higher doses of Ag did not increase response. For NAb, the 3.75 µg + MF59 group had a day 42 SC rate of 84% (95% CI, 76-91) with a GMT of 85 (95% CI, 69-104). Mixing adjuvant with only the first of 2 15 µg doses was comparable to 2 adjuvanted 15 µg doses. Recent seasonal flu vaccination and aging attenuated Ab responses. Ab responses correlated with d8 Ab-secreting B cells (ASC; r=0.43; p=0.01) and CD4+ICOS+CXC3+CXCR5+ T follicular helper cells (TFH; r=0.57; p<0.001) in blood, but not d0 memory B cells. TFH recognized H7 Ag, produced IL21, and trended higher with MF59. There were no vaccine-related serious adverse events and reactogenicity was mostly mild with more frequent local symptoms seen with adjuvanted doses. Conclusion: Point-of-use mixing and administration of 2 doses of H7N9 vaccine (3.75 µg) with MF59 produced d42 SC in 60% of subjects. D8 ASC and CD4 TFH levels correlated with d42 HAI Ab response. The study indicates potential value in this rapid response tactic against H7N9. Remaining questions include Ab duration and protective efficacy.
    IDWeek 2014 Meeting of the Infectious Diseases Society of America; 10/2014
  • Cody Chastain · Susan E. Beekmann · Todd Hulgan · Jack Stapleton ·
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    ABSTRACT: Background: Hepatitis C (HCV) is a prevalent cause of morbidity and mortality. Updated screening guidelines, public awareness campaigns, and new direct-acting antiviral agents are likely to increase the number of patients seeking HCV care. Infectious diseases (ID) physicians have been identified as a group well suited to manage HCV, but the current and anticipated role of ID physicians has not been sufficiently evaluated. Methods: Adult ID physicians were surveyed regarding their opinions and current practices related to HCV care through the Emerging Infections Network (EIN) via a 10-question survey. Results: Of 1,172 EIN members in the U.S., Canada, and Puerto Rico, 550 (47%) responded. Most (71%) responded that ID physicians should evaluate and/or treat all HCV infections with gastroenterology/hepatology support, while a minority (25%) responded that ID physicians should only evaluate and/or treat patients with mild-moderate liver fibrosis or HIV co-infection. Overall, 54% of respondents currently evaluate and/or treat HCV infection in some capacity, either as HCV mono-infection (40%) and/or HIV/HCV co-infection (47%). Fifty-two percent of physicians who do not currently evaluate and/or treat HCV mono-infection indicated interest in doing so in the future. Factors influencing this decision include clinical capacity/infrastructure, interferon-free regimens for all genotypes, and training/experience. Respondents who do not plan to evaluate and/or treat HCV mono-infection in the future (27%) most commonly cited insufficient capacity/infrastructure, lack of desire, and inadequate training/experience as their rationale. Most ID physicians (61%) did not feel that graduate medical education prepared them to evaluate and/or treat HCV, and members indicated a need for a broad range of training resources. Conclusion: More than 90% of respondents believe that ID physicians should be active in HCV management. The majority of ID physicians who wish to manage HCV mono-infection already provide this service, although many may increase this area of their practice. Expanding graduate medical education, emphasizing continuing medical education, and developing novel management paradigms will be necessary to optimize HCV care in the future.
    IDWeek 2014 Meeting of the Infectious Diseases Society of America; 10/2014

  • 10/2014; 1(suppl 1):S66-S69. DOI:10.1093/ofid/ofu083
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    ABSTRACT: Human infections with avian influenza A/H7N9 have resulted in high morbidity and mortality in China.
    JAMA The Journal of the American Medical Association 10/2014; 312(14):1409-1419. DOI:10.1001/jama.2014.12854 · 35.29 Impact Factor
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    ABSTRACT: Hepatitis C virus (HCV) and GB virus type C (GBV-C) are associated with impaired T cell function despite the fact that HCV replicates in hepatocytes and GBV-C in a small proportion of lymphocytes. Recently, we showed that HCV and GBV-C E2-envelope proteins reduce T cell activation via the T cell receptor (TCR) by competing for phosphorylation with a critical kinase in the TCR signaling cascade (Lck). E2 interfered with TCR signaling in E2 expressing cells and in bystander cells. The bystander effect was mediated by virus particles and extracellular microvesicular particles (exosomes). Multiple kinase substrate sites are predicted to reside on viral structural proteins and based on bioinformatic predictions, many RNA virus pathogens may interfere with TCR signaling via a similar mechanism. Identification of T cell inhibitory effects of virus structural proteins may provide novel approaches to enhance the immunogenicity and memory of viral vaccines.
    Transactions of the American Clinical and Climatological Association 08/2014; 125:14-26.
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    ABSTRACT: Some retrospective studies suggest an association between infection with GB-virus C (GBV-C) and non-Hodgkin lymphoma (NHL). We evaluated this association prospectively in a nested case-control study within the U.S. Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO). Cases (N=658) and controls (N=1,316) were individually-matched by age, sex, race/ethnicity, timing of study entry and sample selection. Pre-diagnostic PLCO serum samples were tested for GBV-C RNA (as a measure of active infection) and E2 antibody (active or resolved infection). Logistic regression was used to estimate odds ratios (ORs) for the association between GBV-C and NHL overall and NHL subtypes. Twelve cases (1.8%) and 7 controls (0.5%) were GBV-C RNA positive. GBV-C RNA positivity was associated with NHL overall (OR=3.43, 95% CI=1.35-8.71) and, based on small numbers, diffuse large B-cell lymphoma (OR=5.31, 95% CI=1.54-18.36). The association with NHL persisted when the interval between testing and selection was greater than 4 years (OR=6.00, 95% CI= 1.21- 29.73). In contrast, E2 antibody-positivity was not associated with NHL risk (OR=1.08, 95% CI=0.74-1.58). Our study demonstrates that GBV-C infection precedes development of NHL. GBV-C infection may play an etiologic role in a small proportion of NHL cases, perhaps by causing chronic immune stimulation or impaired immunosurveillance.
    Cancer Research 08/2014; 74(19). DOI:10.1158/0008-5472.CAN-14-0209 · 9.33 Impact Factor
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    ABSTRACT: During HIV infection, IL-10/IL-10 receptor and programmed death-1 (PD-1)/programmed death-1-ligand (PD-L1) interactions have been implicated in the impairment of cytotoxic T lymphocyte (CTL) activity. Despite antiretroviral therapy (ART), attenuated anti-HIV CTL functions present a major hurdle towards curative measures requiring viral eradication. Therefore, deeper understanding of the mechanisms underlying impaired CTL is crucial before HIV viral eradication is viable. The generation of robust CTL activity necessitates interactions between antigen-presenting cells (APC), CD4+ and CD8+ T cells. We have shown that in vitro, IL-10hiPD-L1hi regulatory B cells (Bregs) directly attenuate HIV-specific CD8+-mediated CTL activity. Bregs also modulate APC and CD4+ T cell function; herein we characterize the Breg compartment in uninfected (HIVNEG), HIV-infected "elite controllers" (HIVEC), ART-treated (HIVART), and viremic (HIVvir), subjects, and in vitro, assess the impact of Bregs on anti-HIV CTL generation and activity after reactivation of HIV latent reservoirs using suberoylanilide hydroxamic acid (SAHA). We find that Bregs from HIVEC and HIVART subjects exhibit comparable IL-10 expression levels significantly higher than HIVNEG subjects, but significantly lower than HIVVIR subjects. Bregs from HIVEC and HIVART subjects exhibit comparable PD-L1 expression, significantly higher than in HIVVIR and HIVNEG subjects. SAHA-treated Breg-depleted PBMC from HIVEC and HIVART subjects, displayed enhanced CD4+ T-cell proliferation, significant upregulation of antigen-presentation molecules, increased frequency of CD107a+ and HIV-specific CD8+ T cells, associated with efficient elimination of infected CD4+ T cells, and reduction in integrated viral DNA. Finally, IL-10-R and PD-1 antibody blockade partially reversed Breg-mediated inhibition of CD4+ T-cell proliferation. Our data suggest that, possibly, via an IL-10 and PD-L1 synergistic mechanism; Bregs likely inhibit APC function and CD4+ T-cell proliferation, leading to anti-HIV CTL attenuation, hindering viral eradication.
    PLoS ONE 04/2014; 9(4):e92934. DOI:10.1371/journal.pone.0092934 · 3.23 Impact Factor
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    ABSTRACT: Human Pegivirus (HPgV; previously called GB virus C/hepatitis G virus) has limited pathogenicity despite causing persistent infection, and is associated with prolonged survival in HIV-infected individuals. Although HPgV RNA is found in and produced by T and B lymphocytes, the primary permissive cell type(s) are unknown. We quantified HPgV RNA in highly purified CD4+ and CD8+ T cells, including naïve, central memory, and effector memory populations, and in B cells (CD19+), NK cells (CD56+) cells and monocytes (CD14+) using real time RT-PCR. Single genome sequencing was performed on virus within individual cell types to estimate genetic diversity among cell populations. HPgV RNA was present in CD4+ and CD8+ T lymphocytes (9 of 9 subjects), B lymphocytes (7 of 10), NK cells and monocytes (both 4 of 5). HPgV RNA levels were higher in naïve (CD45RA+) CD4+ cells than in central memory and effector memory cells (p<0.01). HPgV sequences were highly conserved between patients (0.117 ± 0.02 substitutions per site; range 0.58-0.14) and within subjects (0.006 ± 0.003 substitutions per site; range 0.006-0.010). The non-synonymous/synonymous substitution ratio was 0.07 suggesting low selective pressure. CFSE-labeled HPgV RNA-containing particles precipitated by a commercial exosome isolation reagent delivered CSFE to uninfected monocytes, NK cells, T and B lymphocytes, and HPgV RNA was transferred to peripheral blood mononuclear cells with evidence of subsequent viral replication. Thus, HPgV RNA-containing serum particles including microvesicles may contribute to delivery of HPgV to PBMCs in vivo, explaining the apparent broad tropism of this persistent human RNA virus.
    Journal of General Virology 03/2014; 95(Pt_6). DOI:10.1099/vir.0.063016-0 · 3.18 Impact Factor
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    ABSTRACT: GB Virus C (GBV-C) is a non-pathogenic flavivirus, commonly found in HIV infected patients. Studies suggest a survival benefit of GBV-C viremia in HIV infection. Impact of GBV-C viremia was evaluated on clinical outcome in multidrug-resistant HIV. The OPTIMA study enrolled advanced multidrug-resistant HIV patients with a CD4 count ≤300 cells/mm(3) . This study included a subset of OPTIMA patients. Primary endpoints included AIDS events or death. GBV-C status was assessed at baseline and last time point on study by real-time PCR. Cox proportional hazards models were used to determine if CD4 count (</>100/mm(3) ), treatment assignment, presence or disappearance of GBV-C viremia, GBV-C viral load level and Hepatitis C virus antibody status were associated with outcome. Of 288 patients (98% male, baseline mean age 48 years, HIV viral load 4.67 log10 /ml, and CD4 127 cells/mm(3) ), 62 (21.5%) had detectable GBV-C viremia. The mortality rate for GBV-C infected subjects was lower, 19/62 (30.7%) versus 87/226 (38.5%), and time to death shorter (HR 0.67, 95% CI 0.41-1.11), but the results were not significantly different. The time to development of AIDS events was not different (HR 0.90, 95% CI 0.52-1.53). Among covariates, only CD4 count (HR 0.28, CI 0.19-0.42) had a significant survival effect. A trend in decreased mortality was seen in GBV-C+ patients with CD4 <100/mm(3) in multivariate analyses. GBV-C co-infection in multidrug-resistant HIV infected patients was associated with a trend in improved survival but not decreased AIDS events. Analysis was limited by cohort size. J. Med. Virol. © 2013 Wiley Periodicals, Inc.
    Journal of Medical Virology 03/2014; 86(3). DOI:10.1002/jmv.23845 · 2.35 Impact Factor
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    ABSTRACT: Unlabelled: The 2005 consensus proposal for the classification of hepatitis C virus (HCV) presented an agreed and uniform nomenclature for HCV variants and the criteria for their assignment into genotypes and subtypes. Since its publication, the available dataset of HCV sequences has vastly expanded through advancement in nucleotide sequencing technologies and an increasing focus on the role of HCV genetic variation in disease and treatment outcomes. The current study represents a major update to the previous consensus HCV classification, incorporating additional sequence information derived from over 1,300 (near-)complete genome sequences of HCV available on public databases in May 2013. Analysis resolved several nomenclature conflicts between genotype designations and using consensus criteria created a classification of HCV into seven confirmed genotypes and 67 subtypes. There are 21 additional complete coding region sequences of unassigned subtype. The study additionally describes the development of a Web resource hosted by the International Committee for Taxonomy of Viruses (ICTV) that maintains and regularly updates tables of reference isolates, accession numbers, and annotated alignments (http://talk.ictvonline.org/links/hcv/hcv-classification.htm). The Flaviviridae Study Group urges those who need to check or propose new genotypes or subtypes of HCV to contact the Study Group in advance of publication to avoid nomenclature conflicts appearing in the literature. While the criteria for assigning genotypes and subtypes remain unchanged from previous consensus proposals, changes are proposed in the assignment of provisional subtypes, subtype numbering beyond "w," and the nomenclature of intergenotypic recombinant. Conclusion: This study represents an important reference point for the consensus classification of HCV variants that will be of value to researchers working in clinical and basic science fields.
    Hepatology 01/2014; 59(1). DOI:10.1002/hep.26744 · 11.06 Impact Factor

Publication Stats

4k Citations
1,098.28 Total Impact Points


  • 1992-2015
    • University of Iowa
      • • Department of Internal Medicine
      • • Division of Infectious Diseases
      • • Helen C. Levitt Center for Viral Pathogenesis
      • • College of Pharmacy
      Iowa City, Iowa, United States
  • 2014
    • Minneapolis Veterans Affairs Hospital
      Minneapolis, Minnesota, United States
  • 2009
    • Molecular and Cellular Biology Program
      Seattle, Washington, United States
  • 2006
    • Universidade Federal de São Paulo
      San Paulo, São Paulo, Brazil
  • 2004
    • National Institute of Allergy and Infectious Diseases
      Maryland, United States
    • Duke University Medical Center
      Durham, North Carolina, United States
  • 1991-1999
    • University of Iowa Children's Hospital
      Iowa City, Iowa, United States
  • 1998
    • California Pacific Medical Center Research Institute
      • Department of Transplantation
      San Francisco, California, United States
  • 1988
    • University of North Carolina at Chapel Hill
      North Carolina, United States