Faculty Bibliography

CD8 T cells are a potent tool for eliminating intracellular pathogens and tumor cells. Thus, eliciting robust CD8 T-cell immunity is the basis for many vaccines under development. However, the relationship between antigen load and the magnitude of the CD8 T-cell response is not well-described in a human immune response. Here we address this issue by quantifying viral load and the CD8 T-cell response in a cohort of 80 individuals immunized with the live attenuated yellow fever vaccine (YFV-17D) by sampling peripheral blood at days 0, 1, 2, 3, 5, 7, 9, 11, 14, 30, and 90. When the virus load was below a threshold (peak virus load < 225 genomes per mL, or integrated virus load < 400 genome days per mL), the magnitude of the CD8 T-cell response correlated strongly with the virus load (R(2) ∼ 0.63). As the virus load increased above this threshold, the magnitude of the CD8 T-cell responses saturated. Recent advances in CD8 T-cell-based vaccines have focused on replication-incompetent or single-cycle vectors. However, these approaches deliver relatively limited amounts of antigen after immunization. Our results highlight the requirement that T-cell-based vaccines should deliver sufficient antigen during the initial period of the immune response to elicit a large number of CD8 T cells that may be needed for protection.

IMPORTANCE/OBJECTIVE:Safe and effective vaccines and drugs are needed for the prevention and treatment of Ebola virus disease, including following a potentially high-risk exposure such as a needlestick. OBJECTIVE:To assess response to postexposure vaccination in a health care worker who was exposed to the Ebola virus. DESIGN AND SETTING/METHODS:Case report of a physician who experienced a needlestick while working in an Ebola treatment unit in Sierra Leone on September 26, 2014. Medical evacuation to the United States was rapidly initiated. Given the concern about potentially lethal Ebola virus disease, the patient was offered, and provided his consent for, postexposure vaccination with an experimental vaccine available through an emergency Investigational New Drug application. He was vaccinated on September 28, 2014. INTERVENTIONS/METHODS:The vaccine used was VSVΔG-ZEBOV, a replicating, attenuated, recombinant vesicular stomatitis virus (serotype Indiana) whose surface glycoprotein gene was replaced by the Zaire Ebola virus glycoprotein gene. This vaccine has entered a clinical trial for the prevention of Ebola in West Africa. RESULTS:The vaccine was administered 43 hours after the needlestick occurred. Fever and moderate to severe symptoms developed 12 hours after vaccination and diminished over 3 to 4 days. The real-time reverse transcription polymerase chain reaction results were transiently positive for vesicular stomatitis virus nucleoprotein gene and Ebola virus glycoprotein gene (both included in the vaccine) but consistently negative for Ebola virus nucleoprotein gene (not in the vaccine). Early postvaccination cytokine secretion and T lymphocyte and plasmablast activation were detected. Subsequently, Ebola virus glycoprotein-specific antibodies and T cells became detectable, but antibodies against Ebola viral matrix protein 40 (not in the vaccine) were not detected. CONCLUSIONS AND RELEVANCE/CONCLUSIONS:It is unknown if VSVΔG-ZEBOV is safe or effective for postexposure vaccination in humans who have experienced a high-risk occupational exposure to the Ebola virus, such as a needlestick. In this patient, postexposure vaccination with VSVΔG-ZEBOV induced a self-limited febrile syndrome that was associated with transient detection of the recombinant vesicular stomatitis vaccine virus in blood. Strong innate and Ebola-specific adaptive immune responses were detected after vaccination. The clinical syndrome and laboratory evidence were consistent with vaccination response, and no evidence of Ebola virus infection was detected.

BACKGROUND:During the 2009 influenza pandemic both seasonal and 2009 pandemic vaccines were recommended. We conducted a randomized trial of monovalent 2009-H1N1 vaccine and seasonal trivalent inactivated influenza vaccine (IIV3) given sequentially or concurrently to adults. METHODS:Adults randomized to 4 study groups and stratified by age (18-64 and ≥65 years) received 1 dose of seasonal IIV3 or placebo and 2 doses of 2009-H1N1 vaccine or placebo in one of 4 combinations, i.e., H1N1+Placebo/H1N1+Placebo/IIV3 (HP/HP/V3), H1N1+IIV3/H1N1+Placebo/Placebo (HV3/HP/P), H1N1+Placebo/H1N1+IIV3/Placebo (HP/HV3/P), and IIV3+Placebo/H1N1+Placebo/H1N1 (V3P/HP/H). Intramuscular injections were given three times at 21 day intervals. Sera for antibody assays were obtained prior to and 21 days after each vaccination. Reactogenicity and adverse events were monitored. RESULTS:Eight hundred-five (805) adults were enrolled. All combinations of vaccines were safe and well tolerated. In general, one dose of 2009-H1N1 and one dose of IIV3, regardless of sequence or concurrency of administration, were immunogenic in adults. There were no significant differences in geometric mean titers (GMT) or the proportions of subjects with ≥4-fold rise in antibody responses and titers ≥40 for any vaccine group or between age strata for 2009-H1N1 after the first or second dose, although the vaccine sequence affected the titers to the IIV3 antigens. Hemagglutination inhibition antibody (HAI) GMTs against 2009-H1N1 for the combined age strata 21 days after the first 2009-H1N1 dose were 190.4, 182.1, 232.9 and 157.5 for HP/HP/V3, HV3/HP/P, HP/HV3/P and V3P/HP/H, respectively. While IIV3 GMTs were adequate they were generally lower than the 2009-H1N1 GMTs. In a subset of subjects, there was good correlation between HAI and microneutralization (MN) titers (Spearman's correlation coefficient 0.92). CONCLUSIONS:All vaccine combinations were generally well tolerated. Immune responses to one dose of 2009-H1N1 were adequate regardless of the sequence of vaccination in all age groups, but the sequence affected titers to IIV3 antigens.

BACKGROUND:Avian influenza A/H5N1 has threatened human health for nearly 2 decades. Avian influenza A vaccine without adjuvant is poorly immunogenic. A flexible rapid tactic for mass vaccination will be needed if a pandemic occurs. METHODS:A multicenter, randomized, blinded phase 1 clinical trial evaluated safety and antibody responses after point-of-use mixing of influenza A/Indonesia/05/2005 (H5N1) vaccine with MF59 adjuvant. Field-site pharmacies mixed 3.75, 7.5, or 15 mcg of antigen with or without MF59 adjuvant just prior to intramuscular administration on days 0 and 21 of healthy adults aged 18-49 years. RESULTS:Two hundred and seventy subjects were enrolled. After vaccination, titers of hemagglutination inhibition antibody ≥1:40 were achieved in 80% of subjects receiving 3.75 mcg + MF59 vs only 14% receiving 15 mcg without adjuvant (P < .0001). Peak hemagglutination inhibition antibody geometric mean titers for vaccine + MF59 were ∼65 regardless of antigen dose, and neutralizing titers were 2- to 3-fold higher. Vaccine + MF59 produced cross-reactive antibody responses against 4 heterologous H5N1 viruses. Excellent safety and tolerability were demonstrated. CONCLUSIONS:Point-of-use mixing of H5N1 antigen and MF59 adjuvant achieved target antibody titers in a high percentage of subjects and was safe. The feasibility of the point-of-use mixing should be studied further.

IMPORTANCE/OBJECTIVE:The need to respond quickly to potential influenza pandemics is important. Immunologic priming (initial presentation of an antigen to allow antibody responses on revaccination) with vaccine directed toward an older avian influenza H5 strain might lead to secondary antibody responses to a single dose of more current H5 avian influenza vaccine. OBJECTIVES/OBJECTIVE:To assess priming with the older avian influenza A/Vietnam/1203/2004(H5N1) (Vietnam) vaccine and to conduct dose-response studies with vaccine directed against the more contemporary H5N1 avian influenza virus, influenza A/Anhui/01/2005 (Anhui). DESIGN, SETTING, AND PARTICIPANTS/METHODS:Multicenter US randomized clinical trial beginning in June 2010 with follow-up continuing through October 2011 enrolling 72 healthy adults who were vaccinated 1 year previously with the Vietnam vaccine and 565 vaccine-naive adults. INTERVENTIONS/METHODS:Participants who were previously vaccinated with 90 µg of unadjuvanted Vietnam vaccine were randomly assigned to receive 3.75 µg of avian influenza Anhui vaccine with or without MF59 adjuvant, stratified by 1 vs 2 previous doses (1 dose: n = 18 with MF59 and n = 17 without; 2 doses: n = 19 with MF59 and n = 18 without). Vaccine-naive individuals were randomly assigned to receive Ahnui vaccine with or without MF59 adjuvant in 1 of 5 doses (3.75 µg [n = 55 with MF59 and n = 59 without], 7.5 µg [n = 51 with MF59 and n = 57 without], 15 µg [n = 48 with MF59 and n = 44 without], 45 µg [n = 47 with MF59 and n = 47 without], or 90 µg [n = 57 without adjuvant]) or placebo (n = 100) given at days 0 and 28. MAIN OUTCOMES AND MEASURES/METHODS:The primary immunogenicity outcome was hemagglutination inhibition assay (HAI) titer against each vaccine antigen 1 month (day 28) and 6 months (day 180) after last vaccination. The primary safety outcomes were local and systemic adverse events on days 0 to 7 after each vaccination and serious adverse events. RESULTS:Previously vaccinated participants manifested secondary antibody responses after receipt of low-dose Anhui vaccine ("boosting"); by day 28, 21% to 50% developed HAI responses of 1:40 or greater. Use of adjuvant was not associated with increased HAI responses. Among vaccine-naive participants (n = 565), the optimum dose was 7.5 µg of antigen with adjuvant (geometric mean titer [GMT], 63.3; 95% CI, 43.0-93.1). The greatest response to unadjuvanted antigen was seen at the highest dose, 90 µg (GMT, 28.5; 95% CI, 19.7-41.2). Local or systemic reactions occurred, respectively, in 40 (78%) and 25 (49%) of 51 participants who received 7.5 µg plus adjuvant vs 50 (88%) and 29 (51%) of 57 who received 90 µg of unadjuvanted vaccine. In general, antibodies were short-lived, and by day 180, HAI titers had decreased to less than 1:20 in all treatment groups. CONCLUSIONS AND RELEVANCE/CONCLUSIONS:Previous receipt of a single dose of influenza A(H5N1) Vietnam vaccine was associated with sufficient immunologic priming to facilitate antibody response to a different H5N1 antigen using low-dose Anhui (booster) vaccine. In participants who had not previously received H5 vaccine, low-dose Anhui vaccine plus adjuvant was more immunogenic compared with higher doses of unadjuvanted vaccine. TRIAL REGISTRATION/BACKGROUND:clinicaltrials.gov Identifier: NCT00680069.

IMPORTANCE/OBJECTIVE:Human infections with avian influenza A/H7N9 have resulted in high morbidity and mortality in China. OBJECTIVE:To compare safety and immunogenicity of different doses of influenza A/Shanghai/2/13 (H7N9) vaccine mixed with or without the MF59 adjuvant. DESIGN, SETTING, AND PARTICIPANTS/METHODS:Multicenter, randomized, double-blind, phase 2 trial at 4 US sites enrolled 700 adults aged 19 to 64 years beginning in September 2013; 6-month follow-up was completed in May 2014. INTERVENTIONS/METHODS:The H7N9 inactivated virus vaccine was administered intramuscularly on days 0 and 21 at nominal doses of 3.75, 7.5, 15, or 45 µg of hemagglutinin (actual doses approximately 50% higher) with or without the MF59 adjuvant. A total 99, 100, or 101 participants were randomized to each group (7 groups; N = 700). MAIN OUTCOMES AND MEASURES/METHODS:Proportions achieving day 42 antibody titer of 40 or greater or seroconversion (a minimum 4-fold increase to titer ≥40) with the hemagglutination inhibition assay; vaccine-related serious adverse events through month 13; and solicited postvaccination symptoms through day 7. RESULTS:Hemagglutination inhibition antibodies were minimal after participants received an unadjuvanted vaccine. After receiving 2 doses of H7N9 vaccine at a dosage of 3.75 µg plus the MF59 adjuvant, day 42 seroconversion occurred in 58 participants (59%; 95% CI, 48%-68%). The peak seroconversion occurred at day 29 in 62 participants (62%; 95% CI, 52%-72%). The day 42 geometric mean titer was 33.0 (95% CI, 24.7-44.1). Higher antigen doses were not associated with increased response. For the neutralizing antibody assays, after receiving 3.75 µg of H7N9 vaccine plus the MF59 adjuvant, day 42 seroconversion occurred in 81 participants (82%; 95% CI, 73%-89%). The day 42 geometric mean titer was 81.4 (95% CI, 66.6-99.5). There was no statistically significant difference in day 42 hemagglutination inhibition seroconversion after mixing adjuvant with either the first or both 15 µg doses (n = 34 [35%; 95% CI, 25%-45%] vs n = 47 [47%; 95% CI, 37%-58%], respectively; P = .10). Recent receipt of seasonal influenza vaccination and older age were associated with attenuated response. No vaccine-related serious adverse events occurred. Solicited postvaccination symptoms were generally mild with more local symptoms seen in participants who received the adjuvant. CONCLUSIONS AND RELEVANCE/CONCLUSIONS:Point-of-use mixing and administration of 2 doses of H7N9 vaccine at the lowest tested antigen dose with MF59 adjuvant produced seroconversion in 59% of participants. Although these findings indicate potential value in this approach, the study is limited by the absence of antibody data beyond 42 days and the absence of clinical outcomes. TRIAL REGISTRATION/BACKGROUND:clinicaltrials.gov Identifier: NCT01938742.

The emergence of pandemic influenza viruses poses a major public health threat. Therefore, there is a need for a vaccine that can induce broadly cross-reactive antibodies that protect against seasonal as well as pandemic influenza strains. Human broadly neutralizing antibodies directed against highly conserved epitopes in the stem region of influenza virus HA have been recently characterized. However, it remains unknown what the baseline levels are of antibodies and memory B cells that are directed against these conserved epitopes. More importantly, it is also not known to what extent anti-HA stem B-cell responses get boosted in humans after seasonal influenza vaccination. In this study, we have addressed these two outstanding questions. Our data show that: (i) antibodies and memory B cells directed against the conserved HA stem region are prevalent in humans, but their levels are much lower than B-cell responses directed to variable epitopes in the HA head; (ii) current seasonal influenza vaccines are efficient in inducing B-cell responses to the variable HA head region but they fail to boost responses to the conserved HA stem region; and (iii) in striking contrast, immunization of humans with the avian influenza virus H5N1 induced broadly cross-reactive HA stem-specific antibodies. Taken together, our findings provide a potential vaccination strategy where heterologous influenza immunization could be used for increasing the levels of broadly neutralizing antibodies and for priming the human population to respond quickly to emerging pandemic influenza threats.

OBJECTIVES/OBJECTIVE:To examine the associations of homophobia, racism, and resiliency with differences in prevalent HIV infection in black and white men who have sex with men (MSM). METHODS:The Involve[ment]t study is a cohort of black and white MSM aged 18-39 years in Atlanta, GA, designed to evaluate individual, dyadic, and community level factors that might explain racial disparities in HIV prevalence. Participants were recruited irrespective of HIV serostatus from community-based venues and from Internet advertisements and were tested for HIV. We assessed respondents' demographics, whether they had engaged in unprotected anal intercourse (UAI) within the past 6 months, and attitudes about perceived homophobia, perceived racism, and personal resiliency. RESULTS:Compared with white MSM, black MSM were less likely to report UAI in the past 6 months [odds ratio (OR): 0.59, confidence interval (CI): 0.44 to 0.80], more likely to be HIV positive (OR: 5.05, CI: 3.52 to 7.25), and--among those HIV positive--more likely to report not being aware of their HIV infection (OR: 2.58, CI: 1.18 to 5.65). Greater perceived racism was associated with UAI in the black sample (partial odds ratio: 1.48, CI: 1.10 to 1.99). Overall, perceived homophobia, perceived racism, and resilience were not associated with prevalent HIV infection in our samples. Greater resilience was associated with less perceived homophobia in both black and white samples (Spearman r = -0.27, P < 0.001, for both). CONCLUSION/CONCLUSIONS:Future studies of social discrimination at the institutional and network level, than at the individual level, may explain differences in HIV infection in black and white MSM.

BACKGROUND:Clade B DNA and recombinant modified vaccinia Ankara (MVA) vaccines producing virus-like particles displaying trimeric membrane-bound envelope glycoprotein (Env) were tested in a phase 2a trial in human immunodeficiency virus (HIV)-uninfected adults for safety, immunogenicity, and 6-month durability of immune responses. METHODS:A total of 299 individuals received 2 doses of JS7 DNA vaccine and 2 doses of MVA/HIV62B at 0, 2, 4, and 6 months, respectively (the DDMM regimen); 3 doses of MVA/HIV62B at 0, 2, and 6 months (the MMM regimen); or placebo injections. RESULTS:At peak response, 93.2% of the DDMM group and 98.4% of the MMM group had binding antibodies for Env. These binding antibodies were more frequent and of higher magnitude for the transmembrane subunit (gp41) than the receptor-binding subunit (gp120) of Env. For both regimens, response rates were higher for CD4(+) T cells (66.4% in the DDMM group and 43.1% in the MMM group) than for CD8(+) T cells (21.8% in the DDMM group and 14.9% in the MMM group). Responding CD4(+) and CD8(+) T cells were biased toward Gag, and >70% produced 2 or 3 of the 4 cytokines evaluated (ie, interferon γ, interleukin 2, tumor necrosis factor α, and granzyme B). Six months after vaccination, the magnitudes of antibodies and T-cell responses had decreased by <3-fold. CONCLUSIONS:DDMM and MMM vaccinations with virus-like particle-expressing immunogens elicited durable antibody and T-cell responses.

Many vaccines induce protective immunity via antibodies. Systems biology approaches have been used to determine signatures that can be used to predict vaccine-induced immunity in humans, but whether there is a 'universal signature' that can be used to predict antibody responses to any vaccine is unknown. Here we did systems analyses of immune responses to the polysaccharide and conjugate vaccines against meningococcus in healthy adults, in the broader context of published studies of vaccines against yellow fever virus and influenza virus. To achieve this, we did a large-scale network integration of publicly available human blood transcriptomes and systems-scale databases in specific biological contexts and deduced a set of transcription modules in blood. Those modules revealed distinct transcriptional signatures of antibody responses to different classes of vaccines, which provided key insights into primary viral, protein recall and anti-polysaccharide responses. Our results elucidate the early transcriptional programs that orchestrate vaccine immunity in humans and demonstrate the power of integrative network modeling.