Swati B. Gupta

International epidemiology of human pre-existing adenovirus (Ad) type-5, type-6, type-26 and type-36 neutralizing antibodies: Correlates of high Ad5 titers and implications for potential HIV vaccine trials

Replication-defective adenoviruses have been utilized as candidate HIV vaccine vectors. Few studies have described the international epidemiology of pre-existing immunity to adenoviruses. We enrolled 1904 participants in a cross-sectional serological survey at seven sites in Africa, Brazil, and Thailand to assess neutralizing antibodies (NA) for adenovirus types Ad5, Ad6, Ad26 and Ad36. Clinical trial samples were used to assess NA titers from the US and Europe. The proportions of participants that were negative were 14.8% (Ad5), 31.5% (Ad6); 41.2% (Ad26) and 53.6% (Ad36). Adenovirus NA titers varied by geographic location and were higher in non-US and non-European settings, especially Thailand. In multivariate logistic regression analysis, geographic setting (non-US and non-European settings) was statistically significantly associated with having higher Ad5 titers; participants from Thailand had the highest odds of having high Ad5 titers (adjusted OR=3.53, 95% CI: 2.24, 5.57). Regardless of location, titers of Ad5NA were the highest and Ad36 NA were the lowest. Coincident Ad5/6 titers were lower than either Ad5 or Ad6 titers alone. Understanding pre-existing immunity to candidate vaccine vectors may contribute to the evaluation of vaccines in international populations.

Cross-Reactivity of Anti–HIV-1 T Cell Immune Responses among the Major HIV-1 Clades in HIV-1–Positive Individuals from 4 Continents

BACKGROUND The genetic diversity of human immunodeficiency virus type 1 (HIV-1) raises the question of whether vaccines that include a component to elicit antiviral T cell immunity based on a single viral genetic clade could provide cellular immune protection against divergent HIV-1 clades. Therefore, we quantified the cross-clade reactivity, among unvaccinated individuals, of anti-HIV-1 T cell responses to the infecting HIV-1 clade relative to other major circulating clades. METHODS Cellular immune responses to HIV-1 clades A, B, and C were compared by standardized interferon- gamma enzyme-linked immunospot assays among 250 unvaccinated individuals, infected with diverse HIV-1 clades, from Brazil, Malawi, South Africa, Thailand, and the United States. Cross-clade reactivity was evaluated by use of the ratio of responses to heterologous versus homologous (infecting) clades of HIV-1. RESULTS Cellular immune responses were predominantly focused on viral Gag and Nef proteins. Cross-clade reactivity of cellular immune responses to HIV-1 clade A, B, and C proteins was substantial for Nef proteins (ratio, 0.97 [95% confidence interval, 0.89-1.05]) and lower for Gag proteins (ratio, 0.67 [95% confidence interval, 0.62-0.73]). The difference in cross-clade reactivity to Nef and Gag proteins was significant (P<.0001). CONCLUSIONS Cross-clade reactivity of cellular immune responses can be substantial but varies by viral protein.

Detection of HIV vaccine-induced cell-mediated immunity in HIV-seronegative clinical trial participants using an optimized and validated enzyme-linked immunospot assay.

An effective vaccine for HIV is likely to require induction of T-cell-mediated immune responses, and the interferon-γ (IFNγ) enzyme-linked immunospot (ELISPOT) assay has become the most commonly used assay for measuring these responses in vaccine trials. We optimized and validated the HIV ELISPOT assay using an empirical method to establish positivity criteria that results in a ≤1% false-positive rate. Using this assay, we detected a broad range of HIV-specific ELISPOT responses to peptide pools of overlapping 20mers, 15mers, or 9mers in study volunteers receiving DNA- or adenovirus vector-based HIV vaccines and in HIV-seropositive donors. We found that 15mers generally had higher response magnitudes than 20mers and lower false-positive rates than 9mers. These studies show that our validated ELISPOT assay using 15mer peptide pools and the positivity criteria of ≥55 spots per 106 cells and ≥4-fold over mock (negative control) is a sensitive and specific assay for the detection of HIV vaccine-induced cell-mediated immunity.

Estimating the benefit of an HIV-1 vaccine that reduces viral load set point

Vaccines designed to induce cell-mediated immune responses against human immunodeficiency virus (HIV)-1 are being developed. Such vaccines are unlikely to provide sterilizing immunity but may be associated with reduced viral set points after infection. We modeled the potential impact of a vaccine that reduces viral set point after infection, using natural history data from 311 HIV-1 seroconverters. Log-normal parametric regression models were used to estimate the log median time to events of interest. Relative times were estimated for those with viral load set points of 30,000 copies/mL (reference group) versus those with lower viral set points. The time to key clinical events in the course of HIV-1 disease progression was significantly extended for those with viral set points 0.5-1.25 log(10) copies/mL lower than the reference group. By quantifying the anticipated clinical benefits associated with a reduction in viral set point, these findings support the use of virologic end points in HIV-1 vaccine trials.

Phase 2 Placebo-Controlled Trial of Two Vaccines to Prevent Ebola in Liberia

BACKGROUND The safety and efficacy of vaccines to prevent Ebola virus disease (EVD) were unknown when the incidence of EVD was peaking in Liberia. METHODS We initiated a randomized, placebo‐controlled, phase 3 trial of the chimpanzee adenovirus 3 vaccine (ChAd3‐EBO‐Z) and the recombinant vesicular stomatitis virus vaccine (rVSV&Dgr;G‐ZEBOV‐GP) in Liberia. A phase 2 subtrial was embedded to evaluate safety and immunogenicity. Because the incidence of EVD declined in Liberia, the phase 2 component was expanded and the phase 3 component was eliminated. RESULTS A total of 1500 adults underwent randomization and were followed for 12 months. The median age of the participants was 30 years; 36.6% of the participants were women. During the week after the administration of vaccine or placebo, adverse events occurred significantly more often with the active vaccines than with placebo; these events included injection‐site reactions (in 28.5% of the patients in the ChAd3‐EBO‐Z group and 30.9% of those in the rVSV&Dgr;G‐ZEBOV‐GP group, as compared with 6.8% of those in the placebo group), headache (in 25.1% and 31.9%, vs. 16.9%), muscle pain (in 22.3% and 26.9%, vs. 13.3%), feverishness (in 23.9% and 30.5%, vs. 9.0%), and fatigue (in 14.0% and 15.4%, vs. 8.8%) (P<0.001 for all comparisons); these differences were not seen at 1 month. Serious adverse events within 12 months after injection were seen in 40 participants (8.0%) in the ChAd3‐EBO‐Z group, in 47 (9.4%) in the rVSV&Dgr;G‐ZEBOV‐GP group, and in 59 (11.8%) in the placebo group. By 1 month, an antibody response developed in 70.8% of the participants in the ChAd3‐EBO‐Z group and in 83.7% of those in the rVSV&Dgr;G‐ZEBOV‐GP group, as compared with 2.8% of those in the placebo group (P<0.001 for both comparisons). At 12 months, antibody responses in participants in the ChAd3‐EBO‐Z group (63.5%) and in those in the rVSV&Dgr;G‐ZEBOV‐GP group (79.5%) remained significantly greater than in those in the placebo group (6.8%, P<0.001 for both comparisons). CONCLUSIONS A randomized, placebo‐controlled phase 2 trial of two vaccines that was rapidly initiated and completed in Liberia showed the capability of conducting rigorous research during an outbreak. By 1 month after vaccination, the vaccines had elicited immune responses that were largely maintained through 12 months. (Funded by the National Institutes of Allergy and Infectious Diseases and the Liberian Ministry of Health; PREVAIL I ClinicalTrials.gov number, NCT02344407.)

Combined oral contraceptive use increases HPV persistence but not new HPV detection in a cohort of women from Thailand.

BACKGROUND Women diagnosed with cervical cancer report longer duration and more recent use of combined oral contraceptives (COCs). It is unclear how COC use impacts risk of cervical carcinogenesis. METHODS We estimated the risk of new human papillomavirus (HPV) DNA detection and persistence among 1135 human immunodeficiency virus (HIV)-negative women aged 20-37 years from Thailand who were followed for 18 months at 6-month intervals. Type-specific HPV DNA, demographic information, hormonal contraceptive use, sexual behavior, genital tract coinfection, and Papanicolaou test results were assessed at baseline and each follow-up. RESULTS Women who reported current COC use during follow-up were less likely to clear HPV infection compared with nonusers, independent of sexual behavior, and Papanicolaou test diagnosis (AHR: 0.67 [95% CI: .49-.93]). Similar associations were not observed among women reporting current use of depomedroxyprogesterone acetate (DMPA). Neither COC nor DMPA use was significantly associated with new HPV DNA detection. CONCLUSIONS These data do not support the hypothesis that contraceptive use is associated with cervical cancer risk via increased risk of HPV acquisition. The increased risk of HPV persistence observed among current COC users suggests a possible influence of female sex hormones on host response to HPV infection.

The association of hormonal contraceptive use and HPV prevalence.

Women diagnosed with cervical cancer report longer duration and more recent use of combined oral contraceptives (COCs). It is unclear whether COC use is associated with upstream events of human papillomavirus (HPV) infection prior to development of clinical disease. The objective of our study was to assess the association of contraceptive use on the risk for prevalent HPV infection in a cohort of long‐term hormonal contraceptive (HC) users. One thousand and seventy (n = 1,070) HIV‐negative women aged 20–37 from Thailand enrolled in a prospective study of the natural history of HPV. Baseline HPV genotype information, recency and duration of HC use, sexual behavior, other sexually transmitted infection (STI) information and cervical cytology and histology were assessed. At enrollment, 19.8% and 11.5% of women were infected with any HPV or any high‐risk (HR)‐HPV, respectively. After adjustment for age, current and past sexual risk behaviors, STI history and cytology, the use of COCs for >6 years was found to be associated with an increased risk of infection with any HPV [prevalence ratio (PR): 1.88 (1.21, 2.90)] and any HR‐HPV [PR: 2.68 (1.47, 4.88)] as compared to never users. Recent, long‐term COC use was associated with an increased risk for prevalent HPV infection independent of sexual behavior and cervical abnormalities. No similar association was observed for recent or long duration use of progestin‐only contraceptives (i.e., depomedroxyprogesterone acetate). These data suggest that COC use may impact early upstream events in the natural history of HPV infection.

Antibodies to Toxin B Are Protective Against Clostridium difficile Infection Recurrence

BACKGROUND Although newer studies have evaluated risk factors for recurrent Clostridium difficile infection (CDI), the vast majority did not measure important biomarkers such as endogenous anti-toxin A and anti-toxin B antibody levels. METHODS Data from the placebo group of a phase 2 trial testing monoclonal antibodies to C. difficile toxins A and B for preventing CDI recurrence (rCDI) were analyzed to assess risk factors associated with rCDI. Patients with symptomatic CDI taking metronidazole or vancomycin were enrolled. The primary outcome was rCDI within 84 days of treatment start. Univariate and multivariate logistic regression was used to examine associations between potential risk factors and rCDI. At baseline, demographic and clinical characteristics were recorded; endogenous antibody levels were assessed using 2 enzyme-linked immunosorbent assays. RESULTS A predictor of recurrence was age ≥65 years, and an antibody-mediated immune response to toxin B appears to be protective against rCDI. CONCLUSIONS Our findings demonstrate the importance of clinical as well as immunological risk factors in rCDI and provide more robust evidence for the protective effects of antibody to toxin B in the prevention of rCDI. CLINICAL TRIALS REGISTRATION NCT00350298.

Development and Validation of the Influenza Intensity and Impact Questionnaire (FluiiQ

OBJECTIVE Clinical trials of new agents to reduce the severity and impact of influenza require accurate assessment of the effect of influenza infection. Because there are limited high-quality adult influenza Patient Reported Outcomes (PRO) measures, the aim was to develop and validate a simple but comprehensive questionnaire for epidemiological research and clinical trials. METHODS Construct and item generation was guided by the literature, concept mapping, focus groups, and interviews with individuals with laboratory-confirmed influenza and expert physicians. Items were administered to 311 people with influenza-like illness (ILI) across 25 US sites. Analyses included classic psychometrics, structural equation modeling (SEM), and Rasch analyses. RESULTS Concept mapping generated 149 concepts covering the influenza experience and clustered into symptoms and impact on daily activities, emotions, and others. Items were drafted using simplicity and brevity criteria. Eleven symptoms from the literature underwent review by physicians and patients, and two were removed and one added. The symptoms domain factored into systemic and respiratory symptoms, whereas the impact domains were unidimensional. All domains displayed good internal consistency (Cronbach α ≥ 0.8) except the three-item respiratory domain (α = 0.48). A five-factor SEM indicated excellent fit where systemic, respiratory, and daily activities domains differentiated patients with ILI or confirmed influenza. All scales were responsive over time. CONCLUSIONS Patient and clinician consultations resulted in an influenza PRO measure with high validity and good overall evidence of reliability and responsiveness. The Influenza Intensity and Impact Questionnaire (FluiiQ™) will improve the evaluation of existing and future agents designed to prevent or control influenza infection by increasing the breadth and depth of measurement in this field.

Cross-clade reactivity of HIV-1-specific T-cell responses in HIV-1-infected individuals from Botswana and Cameroon

Summary: An effective HIV type 1 (HIV-1) vaccine will likely require elicitation of broadly reactive cell-mediated immune (CMI) responses against divergent HIV-1 clades. We compared anti-HIV-1 T-cell immune responses among 363 unvaccinated adults infected with diverse HIV-1 clades. Response rates to clade B Gag and/or clade B Nef in Botswana (95%) and Cameroon (98%) were similar when compared with those in countries previously studied, including Brazil (92%), Thailand (96%), South Africa (96%), Malawi (100%), and the United States (100%). Substantial cross-clade cell-mediated immune responses in Botswana and Cameroon confirm previous findings in a larger, more genetically diverse collection of HIV-1 samples.