Heterologous cAd3-Ebola and MVA-EbolaZ vaccines are safe and immunogenic in US and Uganda phase 1/1b trials

Ebola virus disease (EVD) is a filoviral infection caused by virus species of the Ebolavirus genus including Zaire ebolavirus (EBOV) and Sudan ebolavirus (SUDV). We investigated the safety and immunogenicity of a heterologous prime-boost regimen involving a chimpanzee adenovirus 3 vectored Ebola vaccine [either monovalent (cAd3-EBOZ) or bivalent (cAd3-EBO)] prime followed by a recombinant modified vaccinia virus Ankara EBOV vaccine (MVA-EbolaZ) boost in two phase 1/1b randomized open-label clinical trials in healthy adults in the United States (US) and Uganda (UG). Trial US (NCT02408913) enrolled 140 participants, including 26 EVD vaccine-naïve and 114 cAd3-Ebola-experienced participants (April-November 2015). Trial UG (NCT02354404) enrolled 90 participants, including 60 EVD vaccine-naïve and 30 DNA Ebola vaccine-experienced participants (February-April 2015). All tested vaccines and regimens were safe and well tolerated with no serious adverse events reported related to study products. Solicited local and systemic reactogenicity was mostly mild to moderate in severity. The heterologous prime-boost regimen was immunogenic, including induction of durable antibody responses which peaked as early as two weeks and persisted up to one year after each vaccination. Different prime-boost intervals impacted the magnitude of humoral and cellular immune responses. The results from these studies demonstrate promising implications for use of these vaccines in both prophylactic and outbreak settings.

High monoclonal neutralization titers reduced breakthrough HIV-1 viral loads in the Antibody Mediated Prevention trials

The Antibody Mediated Prevention (AMP) trials (NCT02716675 and NCT02568215) demonstrated that passive administration of the broadly neutralizing monoclonal antibody VRC01 could prevent some HIV-1 acquisition events. Here, we use mathematical modeling in a post hoc analysis to demonstrate that VRC01 influenced viral loads in AMP participants who acquired HIV. Instantaneous inhibitory potential (IIP), which integrates VRC01 serum concentration and VRC01 sensitivity of acquired viruses in terms of both IC50 and IC80, follows a dose-response relationship with first positive viral load (p = 0.03), which is particularly strong above a threshold of IIP = 1.6 (r = -0.6, p = 2e-4). Mathematical modeling reveals that VRC01 activity predicted from in vitro IC80s and serum VRC01 concentrations overestimates in vivo neutralization by 600-fold (95% CI: 300-1200). The trained model projects that even if future therapeutic HIV trials of combination monoclonal antibodies do not always prevent acquisition, reductions in viremia and reservoir size could be expected.

Natural infection by Zika virus but not DNA vaccination consistently elicits antibodies that compete with two potently neutralising monoclonal antibodies targeting distinct epitopes

BACKGROUND

Autochthonous transmission of Zika virus (ZIKV) has been reported in 87 countries since 2015. Although most infections are mild, there is risk of Guillain-Barré syndrome and adverse pregnancy outcomes. Vaccines are urgently needed to prevent Zika, but sufficient understanding of humoral responses and tools to assess ZIKV-specific immunity are lacking.

METHODS

We developed a blockade-of-binding (BOB) ELISA using A9E and G9E, two strongly neutralising ZIKV-specific monoclonal antibodies, which do not react with dengue virus. Receiver operating characteristic curve analysis assessed A9E and G9E BOB serodiagnostic performance. BOB was then applied to samples from a surveillance cohort in Risaralda, Colombia, and phase 1 ZIKV vaccine trial samples, comparing results against traditional serologic tests.

FINDINGS

In the validation sample set (n = 120), A9E BOB has a sensitivity of 93.5% (95% CI: 79.3, 98.9) and specificity 97.8 (95% CI: 92.2, 99.6). G9E BOB had a sensitivity of 100% (95% CI: 89.0, 100.0) and specificity 100% (95% CI: 95.9, 100). Serum from natural infections consistently tested positive in these assays for up to one year, and reactivity tracks well with ZIKV infection status among sera from endemic areas with complicated flavivirus exposures. Interestingly, a leading ZIKV vaccine candidate elicited minimal BOB reactivity despite generating neutralising antibody responses.

INTERPRETATION

In conclusion, A9E and G9E BOB assays are sensitive and specific assays for detecting antibodies elicited by recent or remote ZIKV infections. Given the additional ability of these BOB assays to detect immune responses that target different epitopes, further development of these assays is well justified for applications including flavivirus surveillance, translational vaccinology research and as potential serologic correlates of protective immunity against Zika.

FUNDING

R21 AI129532 (PI: S. Becker-Dreps), CDCBAA 2017-N-18041 (PI: A. M. de Silva), Thrasher Fund (PI: M. H. Collins), K22 AI137306 (PI: M. H. Collins).

Phase 1 Open-Label Dose Escalation Trial for the Development of a Human Bacillus Calmette-Guérin Challenge Model for Assessment of Tuberculosis Immunity In Vivo

BACKGROUND

A controlled human infection model for assessing tuberculosis (TB) immunity can accelerate new vaccine development.

METHODS

In this phase 1 dose escalation trial, 92 healthy adults received a single intradermal injection of 2 × 106 to 16 × 106 colony-forming units of Bacillus Calmette-Guérin (BCG). The primary endpoints were safety and BCG shedding as measured by quantitative polymerase chain reaction, colony-forming unit plating, and MGIT BACTEC culture.

RESULTS

Doses up to 8 × 106 were safe, and there was evidence for increased BCG shedding with dose escalation. The MGIT time-to-positivity assay was the most consistent and precise measure of shedding. Power analyses indicated that 10% differences in MGIT time to positivity (area under the curve) could be detected in small cohorts (n = 30). Potential biomarkers of mycobacterial immunity were identified that correlated with shedding. Transcriptomic analysis uncovered dose- and time-dependent effects of BCG challenge and identified a putative transcriptional TB protective signature. Furthermore, we identified immunologic and transcriptomal differences that could represent an immune component underlying the observed higher rate of TB disease incidence in males.

CONCLUSIONS

The safety, reactogenicity, and immunogenicity profiles indicate that this BCG human challenge model is feasible for assessing in vivo TB immunity and could facilitate the vaccine development process.

CLINICAL TRIALS REGISTRATION

NCT01868464 (ClinicalTrials.gov).

Adults on pre-exposure prophylaxis (tenofovir-emtricitabine) have faster clearance of anti-HIV monoclonal antibody VRC01

Broadly neutralizing monoclonal antibodies (mAbs) are being developed for HIV-1 prevention. Hence, these mAbs and licensed oral pre-exposure prophylaxis (PrEP) (tenofovir-emtricitabine) can be concomitantly administered in clinical trials. In 48 US participants (men and transgender persons who have sex with men) who received the HIV-1 mAb VRC01 and remained HIV-free in an antibody-mediated-prevention trial (ClinicalTrials.gov #NCT02716675), we conduct a post-hoc analysis and find that VRC01 clearance is 0.08 L/day faster (p = 0.005), and dose-normalized area-under-the-curve of VRC01 serum concentration over-time is 0.29 day/mL lower (p < 0.001) in PrEP users (n = 24) vs. non-PrEP users (n = 24). Consequently, PrEP users are predicted to have 14% lower VRC01 neutralization-mediated prevention efficacy against circulating HIV-1 strains. VRC01 clearance is positively associated (r = 0.33, p = 0.03) with levels of serum intestinal Fatty Acid Binding protein (I-FABP), a marker of epithelial intestinal permeability, which is elevated upon starting PrEP (p = 0.04) and after months of self-reported use (p = 0.001). These findings have implications for the evaluation of future HIV-1 mAbs and postulate a potential mechanism for mAb clearance in the context of PrEP.

Protein dose-sparing effect of AS01B adjuvant in a randomized preventive HIV vaccine trial of ALVAC-HIV (vCP2438) and adjuvanted bivalent subtype C gp120

BACKGROUND

HVTN 120 is a phase 1/2a randomized double-blind placebo-controlled HIV vaccine trial that evaluated the safety and immunogenicity of ALVAC-HIV (vCP2438) and MF59- or AS01B-adjuvanted bivalent subtype C gp120 Env protein at two dose levels in healthy HIV-uninfected adults. Trial registration URL https://clinicaltrials.gov/ct2/show/NCT03122223 and registration number NCT03122223.

METHODS

Participants received ALVAC-HIV (vCP2438) alone or placebo at months 0 and 1. At months 3 and 6, participants received either placebo, ALVAC-HIV (vCP2438) with 200μg of bivalent subtype C gp120 adjuvanted with MF59 or AS01B, or ALVAC-HIV (vCP2438) with 40μg of bivalent subtype C gp120 adjuvanted with AS01B. Primary outcomes were safety and immune responses.

RESULTS

We enrolled 160 participants, 55% females, 18-40 years old (median age 24 years) of whom 150 received vaccine and 10 placebo. Vaccines were generally safe and well tolerated. At months 6.5 and 12, CD4+ T-cell response rates and magnitudes were higher in the AS01B-adjuvanted groups than in the MF59-adjuvanted group. At month 12, HIV-specific Env-gp120 binding antibody response magnitudes in the 40μg gp120/AS01B group were higher than in either of the 200μg gp120 groups.

CONCLUSIONS

The 40μg dose gp120/AS01B regimen elicited the highest CD4+ T-cell and binding antibody responses.

Immunogenicity of NVX-CoV2373 heterologous boost against SARS-CoV-2 variants

As part of a multicenter study evaluating homologous and heterologous COVID-19 booster vaccines, we assessed the magnitude, breadth, and short-term durability of binding and pseudovirus-neutralizing antibody (PsVNA) responses following a single booster dose of NVX-CoV2373 in adults primed with either Ad26.COV2.S, mRNA-1273, or BNT162b2 vaccines. NVX-CoV2373 as a heterologous booster was immunogenic and associated with no safety concerns through Day 91. Fold-rises in PsVNA titers from baseline (Day 1) to Day 29 were highest for prototypic D614G variant and lowest for more recent Omicron sub-lineages BQ.1.1 and XBB.1. Peak humoral responses against all SARS-CoV-2 variants were lower in those primed with Ad26.COV2.S than with mRNA vaccines. Prior SARS CoV-2 infection was associated with substantially higher baseline PsVNA titers, which remained elevated relative to previously uninfected participants through Day 91. These data support the use of heterologous protein-based booster vaccines as an acceptable alternative to mRNA or adenoviral-based COVID-19 booster vaccines. This trial was conducted under ClinicalTrials.gov: NCT04889209.

Pharmacokinetic serum concentrations of VRC01 correlate with prevention of HIV-1 acquisition

BACKGROUND

The phase 2b proof-of-concept Antibody Mediated Prevention (AMP) trials showed that VRC01, an anti-HIV-1 broadly neutralising antibody (bnAb), prevented acquisition of HIV-1 sensitive to VRC01. To inform future study design and dosing regimen selection of candidate bnAbs, we investigated the association of VRC01 serum concentration with HIV-1 acquisition using AMP trial data.

METHODS

The case-control sample included 107 VRC01 recipients who acquired HIV-1 and 82 VRC01 recipients who remained without HIV-1 during the study. We measured VRC01 serum concentrations with a qualified pharmacokinetic (PK) Binding Antibody Multiplex Assay. We employed nonlinear mixed effects PK modelling to estimate daily-grid VRC01 concentrations. Cox regression models were used to assess the association of VRC01 concentration at exposure and baseline body weight, with the hazard of HIV-1 acquisition and prevention efficacy as a function of VRC01 concentration. We also compared fixed dosing vs. body weight-based dosing via simulations.

FINDINGS

Estimated VRC01 concentrations in VRC01 recipients without HIV-1 were higher than those in VRC01 recipients who acquired HIV-1. Body weight was inversely associated with HIV-1 acquisition among both placebo and VRC01 recipients but did not modify the prevention efficacy of VRC01. VRC01 concentration was inversely correlated with HIV-1 acquisition, and positively correlated with prevention efficacy of VRC01. Simulation studies suggest that fixed dosing may be comparable to weight-based dosing in overall predicted prevention efficacy.

INTERPRETATION

These findings suggest that bnAb serum concentration may be a useful marker for dosing regimen selection, and operationally efficient fixed dosing regimens could be considered for future trials of HIV-1 bnAbs.

FUNDING

Was provided by the National Institutes of Health, National Institute of Allergy and Infectious Diseases (NIAID) (UM1 AI068614, to the HIV Vaccine Trials Network [HVTN]; UM1 AI068635, to the HVTN Statistical Data and Management Center [SDMC], Fred Hutchinson Cancer Center [FHCC]; 2R37 054165 to the FHCC; UM1 AI068618, to HVTN Laboratory Center, FHCC; UM1 AI068619, to the HPTN Leadership and Operations Center; UM1 AI068613, to the HIV Prevention Trials Network [HPTN] Laboratory Center; UM1 AI068617, to the HPTN SDMC; and P30 AI027757, to the Center for AIDS Research, Duke University (AI P30 AI064518) and University of Washington (P30 AI027757) Centers for AIDS Research; R37AI054165 from NIAID to the FHCC; and OPP1032144 CA-VIMC Bill & Melinda Gates Foundation.

Counterfactual estimation of efficacy against placebo for novel PrEP agents using external trial data: example of injectable cabotegravir and oral PrEP in women

INTRODUCTION

Multiple antiretroviral agents have demonstrated efficacy for human immunodeficiency virus (HIV) pre-exposure prophylaxis (PrEP). As a result, clinical trials of novel agents have transitioned from placebo- to active-controlled designs; however, active-controlled trials do not provide an estimate of efficacy versus no use of PrEP. Counterfactual placebo comparisons using other data sources could be employed to provide this information.

METHODS

We compared the active-controlled study (HPTN 084) of injectable cabotegravir (CAB-LA) versus daily oral emtricitabine/tenofovir disoproxil fumarate (FTC/TDF) among women from seven countries in Africa to three external, contemporaneous randomized HIV prevention trials from which we constructed counterfactual placebo estimates. We used direct standardization via analysis weights to achieve the same distribution of person-years between the external study and HPTN 084, across strata predictive of HIV risk (country and selected risk covariates). We estimated prevention efficacy against a counterfactual placebo to provide information on the use of CAB-LA and FTC/TDF compared to no intervention. We compared the counterfactual placebo findings for FTC/TDF to previous placebo-controlled trials, adjusted for observed adherence to daily pills.

RESULTS

Distribution of age and baseline prevalence of gonorrhoea and chlamydia were similar among matched counterfactual placebo and observed HPTN 084 arms after standardization. Counterfactual estimates of CAB-LA versus placebo in all three settings showed a consistent risk reduction of 93%-94%, with lower bounds of the confidence intervals above 72%. Observed adherence (quantifiable tenofovir in plasma) in HPTN 084 was 54%-56%, and estimated efficacy of daily oral FTC/TDF against a counterfactual placebo was consistent with a predicted risk reduction of 39%-40% for this level of daily pill use.

CONCLUSIONS

Counterfactual placebo rates of HIV acquisition derived from external trial data in similar locations and time can be used to support estimates of placebo-based efficacy of a novel HIV prevention agent. External trial data must be standardized to be representative of the clinical trial cohort testing the novel HIV prevention agent, accounting for confounders.

Neutralization profiles of HIV-1 viruses from the VRC01 Antibody Mediated Prevention (AMP) trials

The VRC01 Antibody Mediated Prevention (AMP) efficacy trials conducted between 2016 and 2020 showed for the first time that passively administered broadly neutralizing antibodies (bnAbs) could prevent HIV-1 acquisition against bnAb-sensitive viruses. HIV-1 viruses isolated from AMP participants who acquired infection during the study in the sub-Saharan African (HVTN 703/HPTN 081) and the Americas/European (HVTN 704/HPTN 085) trials represent a panel of currently circulating strains of HIV-1 and offer a unique opportunity to investigate the sensitivity of the virus to broadly neutralizing antibodies (bnAbs) being considered for clinical development. Pseudoviruses were constructed using envelope sequences from 218 individuals. The majority of viruses identified were clade B and C; with clades A, D, F and G and recombinants AC and BF detected at lower frequencies. We tested eight bnAbs in clinical development (VRC01, VRC07-523LS, 3BNC117, CAP256.25, PGDM1400, PGT121, 10-1074 and 10E8v4) for neutralization against all AMP placebo viruses (n = 76). Compared to older clade C viruses (1998-2010), the HVTN703/HPTN081 clade C viruses showed increased resistance to VRC07-523LS and CAP256.25. At a concentration of 1μg/ml (IC80), predictive modeling identified the triple combination of V3/V2-glycan/CD4bs-targeting bnAbs (10-1074/PGDM1400/VRC07-523LS) as the best against clade C viruses and a combination of MPER/V3/CD4bs-targeting bnAbs (10E8v4/10-1074/VRC07-523LS) as the best against clade B viruses, due to low coverage of V2-glycan directed bnAbs against clade B viruses. Overall, the AMP placebo viruses represent a valuable resource for defining the sensitivity of contemporaneous circulating viral strains to bnAbs and highlight the need to update reference panels regularly. Our data also suggests that combining bnAbs in passive immunization trials would improve coverage of global viruses.

Safety and Immunogenicity of Ad26-Vectored HIV Vaccine With Mosaic Immunogens and a Novel Mosaic Envelope Protein in HIV-Uninfected Adults: A Phase 1/2a Study

BACKGROUND

Developing a cross-clade, globally effective HIV vaccine remains crucial for eliminating HIV.

METHODS

This placebo-controlled, double-blind, phase 1/2a study enrolled healthy HIV-uninfected adults at low risk for HIV infection. They were randomized (1:4:1) to receive 4 doses of an adenovirus 26-based HIV-1 vaccine encoding 2 mosaic Gag and Pol, and 2 mosaic Env proteins plus adjuvanted clade C gp140 (referred to here as clade C regimen), bivalent protein regimen (clade C regimen plus mosaic gp140), or placebo. Primary end points were safety and antibody responses.

RESULTS

In total 152/155 participants (clade C, n = 26; bivalent protein, n = 103; placebo, n = 26) received ≥1 injection. The highest adverse event (AE) severity was grade 3 (local pain/tenderness, 12%, 2%, and 0% of the respective groups; solicited systemic AEs, 19%, 15%, 0%). HIV-1 mosaic gp140-binding antibody titers were 79 595 ELISA units (EU)/mL and 137 520 EU/mL in the clade C and bivalent protein groups (P < .001) after dose 4 and 16 862 EU/mL and 25 162 EU/mL 6 months later. Antibody response breadth against clade C gp140 and clade C/non-clade C gp120 was highest in the bivalent protein group.

CONCLUSIONS

Adding mosaic gp140 to the clade C regimen increased and broadened the elicited immune response without compromising safety or clade C responses. Clinical Trials Registration. NCT02935686.

Trivalent mosaic or consensus HIV immunogens prime humoral and broader cellular immune responses in adults

BACKGROUNDMosaic and consensus HIV-1 immunogens provide two distinct approaches to elicit greater breadth of coverage against globally circulating HIV-1 and have shown improved immunologic breadth in nonhuman primate models.METHODSThis double-blind randomized trial enrolled 105 healthy HIV-uninfected adults who received 3 doses of either a trivalent global mosaic, a group M consensus (CON-S), or a natural clade B (Nat-B) gp160 env DNA vaccine followed by 2 doses of a heterologous modified vaccinia Ankara-vectored HIV-1 vaccine or placebo. We performed prespecified blinded immunogenicity analyses at day 70 and day 238 after the first immunization. T cell responses to vaccine antigens and 5 heterologous Env variants were fully mapped.RESULTSEnv-specific CD4+ T cell responses were induced in 71% of the mosaic vaccine recipients versus 48% of the CON-S recipients and 48% of the natural Env recipients. The mean number of T cell epitopes recognized was 2.5 (95% CI, 1.2-4.2) for mosaic recipients, 1.6 (95% CI, 0.82-2.6) for CON-S recipients, and 1.1 (95% CI, 0.62-1.71) for Nat-B recipients. Mean breadth was significantly greater in the mosaic group than in the Nat-B group using overall (P = 0.014), prime-matched (P = 0.002), heterologous (P = 0.046), and boost-matched (P = 0.009) measures. Overall T cell breadth was largely due to Env-specific CD4+ T cell responses.CONCLUSIONPriming with a mosaic antigen significantly increased the number of epitopes recognized by Env-specific T cells and enabled more, albeit still limited, cross-recognition of heterologous variants. Mosaic and consensus immunogens are promising approaches to address global diversity of HIV-1.TRIAL REGISTRATIONClinicalTrials.gov NCT02296541.FUNDINGUS NIH grants UM1 AI068614, UM1 AI068635, UM1 AI068618, UM1 AI069412, UL1 RR025758, P30 AI064518, UM1 AI100645, and UM1 AI144371, and Bill & Melinda Gates Foundation grant OPP52282.

Prediction of serum HIV-1 neutralization titers of VRC01 in HIV-uninfected Antibody Mediated Prevention (AMP) trial participants

VRC01 is being evaluated in the AMP efficacy trials, the first assessment of a passively administered broadly neutralizing monoclonal antibody (bnAb) for HIV-1 prevention. A key analysis will assess serum VRC01-mediated neutralization as a potential correlate of protection. To prepare for this analysis, we conducted a pilot study where we measured longitudinal VRC01 serum concentrations and serum VRC01-mediated neutralization in 47 and 31 HIV-1 uninfected AMP participants, respectively. We applied four different statistical approaches to predict serum VRC01-mediated neutralization titer against Env-pseudotyped viruses, including breakthrough viruses isolated from AMP placebo recipients who became HIV-1 infected during the trial, using VRC01 serum concentration and neutralization potency (IC50 or IC80) of the VRC01 clinical lot against the same virus. Approaches 3 and 4, which utilized pharmacokinetics/pharmacodynamics joint modeling of concentration and neutralization titer, generally performed the best or comparably to Approaches 1 and 2, which, respectively, utilized only measured and model-predicted concentration. For prediction of ID80 titers against breakthrough viruses, Approaches 1 and 2 rendered comparable performance to Approaches 3 and 4, and could be reasonable approaches to adopt in practice as they entail reduced assay cost and less complicated statistical analysis. Our results may be applied to future studies of other bnAbs and bnAb combinations to maximize resource efficiency in serum neutralization titer measurement.

Antibody Response to COVID-19 mRNA Vaccine in Patients With Lung Cancer After Primary Immunization and Booster: Reactivity to the SARS-CoV-2 WT Virus and Omicron Variant

PURPOSE

To examine COVID-19 mRNA vaccine-induced binding and neutralizing antibody responses in patients with non-small-cell lung cancer (NSCLC) to SARS-CoV-2 614D (wild type [WT]) strain and variants of concern after the primary 2-dose and booster vaccination.

METHODS

Eighty-two patients with NSCLC and 53 healthy volunteers who received SARS-CoV-2 mRNA vaccines were included in the study. Blood was collected longitudinally, and SARS-CoV-2-specific binding and neutralizing antibody responses were evaluated by Meso Scale Discovery assay and live virus Focus Reduction Neutralization Assay, respectively.

RESULTS

A majority of patients with NSCLC generated binding and neutralizing antibody titers comparable with the healthy vaccinees after mRNA vaccination, but a subset of patients with NSCLC (25%) made poor responses, resulting in overall lower (six- to seven-fold) titers compared with the healthy cohort (P = < .0001). Although patients age > 70 years had lower immunoglobulin G titers (P = < .01), patients receiving programmed death-1 monotherapy, chemotherapy, or a combination of both did not have a significant impact on the antibody response. Neutralizing antibody titers to the B.1.617.2 (Delta), B.1.351 (Beta), and in particular, B.1.1.529 (Omicron) variants were significantly lower (P = < .0001) compared with the 614D (WT) strain. Booster vaccination led to a significant increase (P = .0001) in the binding and neutralizing antibody titers to the WT and Omicron variant. However, 2-4 months after the booster, we observed a five- to seven-fold decrease in neutralizing titers to WT and Omicron viruses.

CONCLUSION

A subset of patients with NSCLC responded poorly to the SARS-CoV-2 mRNA vaccination and had low neutralizing antibodies to the B.1.1.529 Omicron variant. Booster vaccination increased binding and neutralizing antibody titers to Omicron, but antibody titers declined after 3 months. These data highlight the concern for patients with cancer given the rapid spread of SARS-CoV-2 Omicron variant.

Baseline host determinants of robust human HIV-1 vaccine-induced immune responses: A meta-analysis of 26 vaccine regimens

BACKGROUND

The identification of baseline host determinants that associate with robust HIV-1 vaccine-induced immune responses could aid HIV-1 vaccine development. We aimed to assess both the collective and relative performance of baseline characteristics in classifying individual participants in nine different Phase 1-2 HIV-1 vaccine clinical trials (26 vaccine regimens, conducted in Africa and in the Americas) as High HIV-1 vaccine responders.

METHODS

This was a meta-analysis of individual participant data, with studies chosen based on participant-level (vs. study-level summary) data availability within the HIV-1 Vaccine Trials Network. We assessed the performance of 25 baseline characteristics (demographics, safety haematological measurements, vital signs, assay background measurements) and estimated the relative importance of each characteristic in classifying 831 participants as High (defined as within the top 25th percentile among positive responders or above the assay upper limit of quantification) versus Non-High responders. Immune response outcomes included HIV-1-specific serum IgG binding antibodies and Env-specific CD4+ T-cell responses assessed two weeks post-last dose, all measured at central HVTN laboratories. Three variable importance approaches based on SuperLearner ensemble machine learning were considered.

FINDINGS

Overall, 30.1%, 50.5%, 36.2%, and 13.9% of participants were categorized as High responders for gp120 IgG, gp140 IgG, gp41 IgG, and Env-specific CD4+ T-cell vaccine-induced responses, respectively. When including all baseline characteristics, moderate performance was achieved for the classification of High responder status for the binding antibody responses, with cross-validated areas under the ROC curve (CV-AUC) of 0.72 (95% CI: 0.68, 0.76) for gp120 IgG, 0.73 (0.69, 0.76) for gp140 IgG, and 0.67 (95% CI: 0.63, 0.72) for gp41 IgG. In contrast, the collection of all baseline characteristics yielded little improvement over chance for predicting High Env-specific CD4+ T-cell responses [CV-AUC: 0.53 (0.48, 0.58)]. While estimated variable importance patterns differed across the three approaches, female sex assigned at birth, lower height, and higher total white blood cell count emerged as significant predictors of High responder status across multiple immune response outcomes using Approach 1. Of these three baseline variables, total white blood cell count ranked highly across all three approaches for predicting vaccine-induced gp41 and gp140 High responder status.

INTERPRETATION

The identified features should be studied further in pursuit of intervention strategies to improve vaccine responses and may be adjusted for in analyses of immune response data to enhance statistical power.

FUNDING

National Institute of Allergy and Infectious Diseases (UM1AI068635 to YH, UM1AI068614 to GDT, UM1AI068618 to MJM, and UM1 AI069511 to MCK), the Duke CFAR P30 AI064518 to GDT, and National Institute of Dental and Craniofacial Research (R01DE027245 to JJK). This work was also supported by the Bill and Melinda Gates Foundation. The content is solely the responsibility of the authors and does not necessarily represent the official views of any of the funding sources.

Safety and immunogenicity of a trivalent virus-like particle vaccine against western, eastern, and Venezuelan equine encephalitis viruses: a phase 1, open-label, dose-escalation, randomised clinical trial

BACKGROUND

Western (WEEV), eastern (EEEV), and Venezuelan (VEEV) equine encephalitis viruses are mosquito-borne pathogens classified as potential biological warfare agents for which there are currently no approved human vaccines or therapies. We aimed to evaluate the safety, tolerability, and immunogenicity of an investigational trivalent virus-like particle (VLP) vaccine, western, eastern, and Venezuelan equine encephalitis (WEVEE) VLP, composed of WEEV, EEEV, and VEEV VLPs.

METHODS

The WEVEE VLP vaccine was evaluated in a phase 1, randomised, open-label, dose-escalation trial at the Hope Clinic of the Emory Vaccine Center at Emory University, Atlanta, GA, USA. Eligible participants were healthy adults aged 18-50 years with no previous vaccination history with an investigational alphavirus vaccine. Participants were assigned to a dose group of 6 μg, 30 μg, or 60 μg vaccine product and were randomly assigned (1:1) to receive the WEVEE VLP vaccine with or without aluminium hydroxide suspension (alum) adjuvant by intramuscular injection at study day 0 and at week 8. The primary outcomes were the safety and tolerability of the vaccine (assessed in all participants who received at least one administration of study product) and the secondary outcome was immune response measured as neutralising titres by plaque reduction neutralisation test (PRNT) 4 weeks after the second vaccination. This trial is registered at ClinicalTrials.gov, NCT03879603.

FINDINGS

Between April 2, 2019, and June 13, 2019, 30 trial participants were enrolled (mean age 32 years, range 21-48; 16 [53%] female participants and 14 [47%] male participants). Six groups of five participants each received 6 μg, 30 μg, or 60 μg vaccine doses with or without adjuvant, and all 30 participants completed study follow-up. Vaccinations were safe and well tolerated. The most frequently reported symptoms were mild injection-site pain and tenderness (22 [73%] of 30) and malaise (15 [50%] of 30). Dose-dependent differences in the frequency of pain and tenderness were found between the 6 μg, 30 μg, and 60 μg groups (p=0·0217). No significant differences were observed between dosing groups for any other reactogenicity symptom. Two adverse events (mild elevated blood pressure and moderate asymptomatic neutropenia) were assessed as possibly related to the study product in one trial participant (60 μg dose with alum); both resolved without clinical sequelae. 4 weeks after second vaccine administration, neutralising antibodies were induced in all study groups with the highest response seen against all three vaccine antigens in the 30 μg plus alum group (PRNT₈₀ geometric mean titre for EEEV 60·8, 95% CI 29·9-124·0; for VEEV 111·5, 49·8-249·8; and for WEEV 187·9, 90·0-392·2). Finally, 4 weeks after second vaccine administration, for all doses, the majority of trial participants developed an immune response to all three vaccine components (24 [83%] of 29 for EEEV; 26 [90%] of 29 for VEEV; 27 [93%] of 29 for WEEV; and 22 [76%] of 29 for EEEV, VEEV, and WEEV combined).

INTERPRETATION

The favourable safety profile and neutralising antibody responses, along with pressing public health need, support further evaluation of the WEVEE VLP vaccine in advanced-phase clinical trials.

FUNDING

The Vaccine Research Center of the National Institute of Allergy and Infectious Diseases, National Institutes of Health funded the clinical trial. The US Department of Defense contributed funding for manufacturing of the study product.

Rapid decline in vaccine-boosted neutralizing antibodies against SARS-CoV-2 Omicron variant

The Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exhibits reduced susceptibility to vaccine-induced neutralizing antibodies, requiring a boost to generate protective immunity. We assess the magnitude and short-term durability of neutralizing antibodies after homologous and heterologous boosting with mRNA and Ad26.COV2.S vaccines. All prime-boost combinations substantially increase the neutralization titers to Omicron, although the boosted titers decline rapidly within 2 months from the peak response compared with boosted titers against the prototypic D614G variant. Boosted Omicron neutralization titers are substantially higher for homologous mRNA vaccine boosting, and for heterologous mRNA and Ad26.COV2.S vaccine boosting, compared with homologous Ad26.COV2.S boosting. Homologous mRNA vaccine boosting generates nearly equivalent neutralizing activity against Omicron sublineages BA.1, BA.2, and BA.3 but modestly reduced neutralizing activity against BA.2.12.1 and BA.4/BA.5 compared with BA.1. These results have implications for boosting requirements to protect against Omicron and future variants of SARS-CoV-2. This trial was conducted under ClincalTrials.gov: NCT04889209.

Infusion Reactions After Receiving the Broadly Neutralizing Antibody VRC01 or Placebo to Reduce HIV-1 Acquisition: Results From the Phase 2b Antibody-Mediated Prevention Randomized Trials

BACKGROUND

The antibody-mediated prevention (AMP) studies (HVTN 703/HPTN 081 and HVTN 704/HPTN 085) are harmonized phase 2b trials to assess HIV prevention efficacy and safety of intravenous infusion of anti-gp120 broadly neutralizing antibody VRC01. Antibodies for other indications can elicit infusion-related reactions (IRRs), often requiring premedication and limiting their application. We report on AMP study IRRs.

METHODS

From 2016 to 2018, 2699 HIV-uninfected, at-risk men and transgender adults in the Americas and Switzerland (704/085) and 1924 at-risk heterosexual women in sub-Saharan Africa (703/081) were randomized 1:1:1 to VRC01 10 mg/kg, 30 mg/kg, or placebo. Participants received infusions every 8 weeks (n = 10/participant) over 72 weeks, with 104 weeks of follow-up. Safety assessments were conducted before and after infusion and at noninfusion visits. A total of 40,674 infusions were administered.

RESULTS

Forty-seven participants (1.7%) experienced 49 IRRs in 704/085; 93 (4.8%) experienced 111 IRRs in 703/081 (P < 0.001). IRRs occurred more frequently in VRC01 than placebo recipients in 703/081 (P < 0.001). IRRs were associated with atopic history (P = 0.046) and with younger age (P = 0.023) in 703/081. Four clinical phenotypes of IRRs were observed: urticaria, dyspnea, dyspnea with rash, and "other." Urticaria was most prevalent, occurring in 25 (0.9%) participants in 704/085 and 41 (2.1%) participants in 703/081. Most IRRs occurred with the initial infusion and incidence diminished through the last infusion. All reactions were managed successfully without sequelae.

CONCLUSIONS

IRRs in the AMP studies were uncommon, typically mild or moderate, successfully managed at the research clinic, and resolved without sequelae. Analysis is ongoing to explore potential IRR mechanisms.

Homologous and Heterologous Covid-19 Booster Vaccinations

BACKGROUND

Although the three vaccines against coronavirus disease 2019 (Covid-19) that have received emergency use authorization in the United States are highly effective, breakthrough infections are occurring. Data are needed on the serial use of homologous boosters (same as the primary vaccine) and heterologous boosters (different from the primary vaccine) in fully vaccinated recipients.

METHODS

In this phase 1-2, open-label clinical trial conducted at 10 sites in the United States, adults who had completed a Covid-19 vaccine regimen at least 12 weeks earlier and had no reported history of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection received a booster injection with one of three vaccines: mRNA-1273 (Moderna) at a dose of 100 μg, Ad26.COV2.S (Johnson & Johnson-Janssen) at a dose of 5×10¹⁰ virus particles, or BNT162b2 (Pfizer-BioNTech) at a dose of 30 μg. The primary end points were safety, reactogenicity, and humoral immunogenicity on trial days 15 and 29.

RESULTS

Of the 458 participants who were enrolled in the trial, 154 received mRNA-1273, 150 received Ad26.COV2.S, and 153 received BNT162b2 as booster vaccines; 1 participant did not receive the assigned vaccine. Reactogenicity was similar to that reported for the primary series. More than half the recipients reported having injection-site pain, malaise, headache, or myalgia. For all combinations, antibody neutralizing titers against a SARS-CoV-2 D614G pseudovirus increased by a factor of 4 to 73, and binding titers increased by a factor of 5 to 55. Homologous boosters increased neutralizing antibody titers by a factor of 4 to 20, whereas heterologous boosters increased titers by a factor of 6 to 73. Spike-specific T-cell responses increased in all but the homologous Ad26.COV2.S-boosted subgroup. CD8+ T-cell levels were more durable in the Ad26.COV2.S-primed recipients, and heterologous boosting with the Ad26.COV2.S vaccine substantially increased spike-specific CD8+ T cells in the mRNA vaccine recipients.

CONCLUSIONS

Homologous and heterologous booster vaccines had an acceptable safety profile and were immunogenic in adults who had completed a primary Covid-19 vaccine regimen at least 12 weeks earlier. (Funded by the National Institute of Allergy and Infectious Diseases; DMID 21-0012 ClinicalTrials.gov number, NCT04889209.).

EVITA Dengue: a cluster-randomized controlled trial to EValuate the efficacy of Wolbachia-InfecTed Aedes aegypti mosquitoes in reducing the incidence of Arboviral infection in Brazil

Background

Arboviruses transmitted by Aedes aegypti including dengue, Zika, and chikungunya are a major global health problem, with over 2.5 billion at risk for dengue alone. There are no licensed antivirals for these infections, and safe and effective vaccines are not yet widely available. Thus, prevention of arbovirus transmission by vector modification is a novel approach being pursued by multiple researchers. However, the field needs high-quality evidence derived from randomized, controlled trials upon which to base the implementation and maintenance of vector control programs. Here, we report the EVITA Dengue trial design (DMID 17-0111), which assesses the efficacy in decreasing arbovirus transmission of an innovative approach developed by the World Mosquito Program for vector modification of Aedes mosquitoes by Wolbachia pipientis.

Methods

DMID 17-0111 is a cluster-randomized trial in Belo Horizonte, Brazil, with clusters defined by primary school catchment areas. Clusters (n = 58) will be randomized 1:1 to intervention (release of Wolbachia-infected Aedes aegypti mosquitoes) vs. control (no release). Standard vector control activities (i.e., insecticides and education campaigns for reduction of mosquito breeding sites) will continue as per current practice in the municipality. Participants (n = 3480, 60 per cluster) are children aged 6–11 years enrolled in the cluster-defining school and living within the cluster boundaries who will undergo annual serologic surveillance for arboviral infection. The primary objective is to compare sero-incidence of arboviral infection between arms.

Discussion

DMID 17-0111 aims to determine the efficacy of Wolbachia-infected mosquito releases in reducing human infections by arboviruses transmitted by Aedes aegypti and will complement the mounting evidence for this method from large-scale field releases and ongoing trials. The trial also represents a critical step towards robustness and rigor for how vector control methods are assessed, including the simultaneous measurement and correlation of entomologic and epidemiologic outcomes. Data from this trial will inform further the development of novel vector control methods.

Trial registration

ClinicalTrials.govNCT04514107. Registered on 17 August 2020

Primary sponsor: National Institute of Health, National Institute of Allergy and Infectious Diseases

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-05997-4.

Antibody response to SARS-CoV-2 mRNA vaccine in lung cancer patients: Reactivity to vaccine antigen and variants of concern

PURPOSE

We investigated SARS-CoV-2 mRNA vaccine-induced binding and live-virus neutralizing antibody response in NSCLC patients to the SARS-CoV-2 wild type strain and the emerging Delta and Omicron variants.

METHODS

82 NSCLC patients and 53 healthy adult volunteers who received SARS-CoV-2 mRNA vaccines were included in the study. Blood was collected longitudinally, and SARS-CoV-2-specific binding and live-virus neutralization response to 614D (WT), B.1.617.2 (Delta), B.1.351 (Beta) and B.1.1.529 (Omicron) variants were evaluated by Meso Scale Discovery (MSD) assay and Focus Reduction Neutralization Assay (FRNT) respectively. We determined the longevity and persistence of vaccine-induced antibody response in NSCLC patients. The effect of vaccine-type, age, gender, race and cancer therapy on the antibody response was evaluated.

RESULTS

Binding antibody titer to the mRNA vaccines were lower in the NSCLC patients compared to the healthy volunteers (P=<0.0001). More importantly, NSCLC patients had reduced live-virus neutralizing activity compared to the healthy vaccinees (P=<0.0001). Spike and RBD-specific binding IgG titers peaked after a week following the second vaccine dose and declined after six months (P=<0.001). While patients >70 years had lower IgG titers (P=<0.01), patients receiving either PD-1 monotherapy, chemotherapy or a combination of both did not have a significant impact on the antibody response. Binding antibody titers to the Delta and Beta variants were lower compared to the WT strain (P=<0.0001). Importantly, we observed significantly lower FRNT50 titers to Delta (6-fold), and Omicron (79-fold) variants (P=<0.0001) in NSCLC patients.

CONCLUSIONS

Binding and live-virus neutralizing antibody titers to SARS-CoV-2 mRNA vaccines in NSCLC patients were lower than the healthy vaccinees, with significantly lower live-virus neutralization of B.1.617.2 (Delta), and more importantly, the B.1.1.529 (Omicron) variant compared to the wild-type strain. These data highlight the concern for cancer patients given the rapid spread of SARS-CoV-2 Omicron variant.

Application of SARS-CoV-2 Serology to Address Public Health Priorities

Background: Antibodies against SARS-CoV-2 can be detected by various testing platforms, but a detailed understanding of assay performance is critical. Methods: We developed and validated a simple enzyme-linked immunosorbent assay (ELISA) to detect IgG binding to the receptor-binding domain (RBD) of SARS-CoV-2, which was then applied for surveillance. ELISA results were compared to a set of complimentary serologic assays using a large panel of clinical research samples. Results: The RBD ELISA exhibited robust performance in ROC curve analysis (AUC> 0.99; Se = 89%, Sp = 99.3%). Antibodies were detected in 23/353 (6.5%) healthcare workers, 6/9 RT-PCR-confirmed mild COVID-19 cases, and 0/30 non-COVID-19 cases from an ambulatory site. RBD ELISA showed a positive correlation with neutralizing activity (p = <0.0001, R2 = 0.26). Conclusions: We applied a validated SARS-CoV-2-specific IgG ELISA in multiple contexts and performed orthogonal testing on samples. This study demonstrates the utility of a simple serologic assay for detecting prior SARS-CoV-2 infection, particularly as a tool for efficiently testing large numbers of samples as in population surveillance. Our work also highlights that precise understanding of SARS-CoV-2 infection and immunity at the individual level, particularly with wide availability of vaccination, may be improved by orthogonal testing and/or more complex assays such as multiplex bead assays.

Evaluation of a SARS-CoV-2 Capture IgM Antibody Assay in Convalescent Sera

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for a global pandemic with over 152 million cases and 3.19 million deaths reported by early May 2021. Understanding the serological response to SARS-CoV-2 is critical to determining the burden of infection and disease (coronavirus disease 2019 [COVID-19]) and transmission dynamics. We developed a capture IgM assay because it should have better sensitivity and specificity than the commonly used indirect assay. Here, we report the development and performance of a capture IgM enzyme-linked immunosorbent assay (ELISA) and a companion indirect IgG ELISA for the spike (S) and nucleocapsid (N) proteins and the receptor-binding domain (RBD) of S. We found that among the IgM ELISAs, the S ELISA was positive in 76% of 55 serum samples from SARS-CoV-2 PCR-positive patients, the RBD ELISA was positive in 55% of samples, and the N ELISA was positive in 15% of samples. The companion indirect IgG ELISAs were positive for S in 89% of the 55 serum samples, RBD in 78%, and N in 85%. While the specificities for IgM RBD, S, and N ELISAs and IgG S and RBD ELISAs were 97% to 100%, the specificity of the N IgG ELISA was lower (89%). RBD-specific IgM antibodies became undetectable by 3 to 6 months, and S IgM reached low levels at 6 months. The corresponding IgG S, RBD, and N antibodies persisted with some decreases in levels over this time period. These capture IgM ELISAs and the companion indirect IgG ELISAs should enhance serologic studies of SARS-CoV-2 infections. IMPORTANCE Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has inflicted tremendous loss of lives, overwhelmed health care systems, and disrupted all aspects of life worldwide since its emergence in Wuhan, China, in December 2019. Detecting current and past infection by PCR or serology is important to understanding and controlling SARS-CoV-2. With increasing prevalence of past infection or vaccination, IgG antibodies are less helpful in diagnosing a current infection. IgM antibodies indicate a more recent infection and can supplement PCR diagnosis. We report an alternative method, capture IgM, to detect serum IgM antibodies, which should be more sensitive and specific than most currently used methods. We describe this capture IgM assay and a companion indirect IgG assay for the SARS-CoV-2 spike (S), nucleocapsid (N), and receptor-binding domain (RBD) proteins. These assays can add value to diagnostic and serologic studies of coronavirus disease 2019 (COVID-19).

Heterologous SARS-CoV-2 Booster Vaccinations - Preliminary Report

Background

While Coronavirus disease 2019 (Covid-19) vaccines are highly effective, breakthrough infections are occurring. Booster vaccinations have recently received emergency use authorization (EUA) for certain populations but are restricted to homologous mRNA vaccines. We evaluated homologous and heterologous booster vaccination in persons who had received an EUA Covid-19 vaccine regimen.

Methods

In this phase 1/2 open-label clinical trial conducted at ten U.S. sites, adults who received one of three EUA Covid-19 vaccines at least 12 weeks prior to enrollment and had no reported history of SARS-CoV-2 infection received a booster injection with one of three vaccines (Moderna mRNA-1273 100-μg, Janssen Ad26.COV2.S 5×1010 virus particles, or Pfizer-BioNTech BNT162b2 30-μg; nine combinations). The primary outcomes were safety, reactogenicity, and humoral immunogenicity on study days 15 and 29.

Results

458 individuals were enrolled: 154 received mRNA-1273, 150 received Ad26.CoV2.S, and 153 received BNT162b2 booster vaccines. Reactogenicity was similar to that reported for the primary series. Injection site pain, malaise, headache, and myalgia occurred in more than half the participants. Booster vaccines increased the neutralizing activity against a D614G pseudovirus (4.2-76-fold) and binding antibody titers (4.6-56-fold) for all combinations; homologous boost increased neutralizing antibody titers 4.2-20-fold whereas heterologous boost increased titers 6.2-76-fold. Day 15 neutralizing and binding antibody titers varied by 28.7-fold and 20.9-fold, respectively, across the nine prime-boost combinations.

Conclusion

Homologous and heterologous booster vaccinations were well-tolerated and immunogenic in adults who completed a primary Covid-19 vaccine regimen at least 12 weeks earlier.

Longitudinal analysis shows durable and broad immune memory after SARS-CoV-2 infection with persisting antibody responses and memory B and T cells

Ending the COVID-19 pandemic will require long-lived immunity to SARS-CoV-2. Here, we evaluate 254 COVID-19 patients longitudinally up to 8 months and find durable broad-based immune responses. SARS-CoV-2 spike binding and neutralizing antibodies exhibit a bi-phasic decay with an extended half-life of >200 days suggesting the generation of longer-lived plasma cells. SARS-CoV-2 infection also boosts antibody titers to SARS-CoV-1 and common betacoronaviruses. In addition, spike-specific IgG+ memory B cells persist, which bodes well for a rapid antibody response upon virus re-exposure or vaccination. Virus-specific CD4+ and CD8+ T cells are polyfunctional and maintained with an estimated half-life of 200 days. Interestingly, CD4+ T cell responses equally target several SARS-CoV-2 proteins, whereas the CD8+ T cell responses preferentially target the nucleoprotein, highlighting the potential importance of including the nucleoprotein in future vaccines. Taken together, these results suggest that broad and effective immunity may persist long-term in recovered COVID-19 patients.

Effect of Monoclonal Antibody Treatment on Clinical Outcomes in Ambulatory Patients With Coronavirus Disease 2019

We compared rates of emergency department visits or hospitalizations among ambulatory coronavirus disease 2019 (COVID-19) patients treated with monoclonal antibody (mAb) therapy (n = 305) vs untreated patients (n = 6354). Treatment was associated with decreased encounters within 30 days (adjusted odds ratio, 0.23 [95% confidence interval, .15-.36]). Our findings support treatment of acute COVID-19 with mAbs.

Longitudinal analysis shows durable and broad immune memory after SARS-CoV-2 infection with persisting antibody responses and memory B and T cells

Ending the COVID-19 pandemic will require long-lived immunity to SARS-CoV-2. Here, we evaluate 254 COVID-19 patients longitudinally up to eight months and find durable broad-based immune responses. SARS-CoV-2 spike binding and neutralizing antibodies exhibit a bi-phasic decay with an extended half-life of >200 days suggesting the generation of longer-lived plasma cells. SARS-CoV-2 infection also boosts antibody titers to SARS-CoV-1 and common betacoronaviruses. In addition, spike-specific IgG+ memory B cells persist, which bodes well for a rapid antibody response upon virus re-exposure or vaccination. Virus-specific CD4+ and CD8+ T cells are polyfunctional and maintained with an estimated half-life of 200 days. Interestingly, CD4+ T cell responses equally target several SARS-CoV-2 proteins, whereas the CD8+ T cell responses preferentially target the nucleoprotein, highlighting the potential importance of including the nucleoprotein in future vaccines. Taken together, these results suggest that broad and effective immunity may persist long-term in recovered COVID-19 patients.

Evaluation of Cellular and Serological Responses to Acute SARS-CoV-2 Infection Demonstrates the Functional Importance of the Receptor-Binding Domain

The factors that control the development of an effective immune response to the recently emerged SARS-CoV-2 virus are poorly understood. In this study, we provide a cross-sectional analysis of the dynamics of B cell responses to SARS-CoV-2 infection in hospitalized COVID-19 patients. We observe changes in B cell subsets consistent with a robust humoral immune response, including significant expansion of plasmablasts and activated receptor-binding domain (RBD)-specific memory B cell populations. We observe elevated titers of Abs to SARS-CoV-2 RBD, full-length Spike, and nucleoprotein over the course of infection, with higher levels of RBD-specific IgG correlating with increased serum neutralization. Depletion of RBD-specific Abs from serum removed a major portion of neutralizing activity in most individuals. Some donors did retain significant residual neutralization activity, suggesting a potential Ab subset targeting non-RBD epitopes. Taken together, these findings are instructive for future vaccine design and mAb strategies.

A Phase 2b Study to Evaluate the Safety and Efficacy of VRC01 Broadly Neutralizing Monoclonal Antibody in Reducing Acquisition of HIV-1 Infection in Women in Sub-Saharan Africa: Baseline Findings

BACKGROUND

HIV Vaccine Trials Network 703/HIV Prevention Trials Network 081 is a phase 2b randomized, double-blind, placebo-controlled trial to assess the safety and efficacy of passively infused monoclonal antibody VRC01 in preventing HIV acquisition in heterosexual women between the ages of 18 and 50 years at risk of HIV. Participants were enrolled at 20 sites in Botswana, Kenya, Malawi, Mozambique, South Africa, Tanzania, and Zimbabwe. It is one of the 2 Antibody Mediated Prevention efficacy trials, with HIV Vaccine Trials Network 704/HIV Prevention Trials Network 085, evaluating VRC01 for HIV prevention.

METHODS

Intense community engagement was used to optimize participant recruitment and retention. Participants were randomly assigned to receive intravenous VRC01 10 mg/kg, VRC01 30 mg/kg, or placebo in a 1:1:1 ratio. Infusions were given every 8 weeks with a total of 10 infusions and 104 weeks of follow-up after the first infusion.

RESULTS

Between May 2016 and September 2018, 1924 women from sub-Saharan Africa were enrolled. The median age was 26 years (interquartile range: 22-30), and 98.9% were Black. Sexually transmitted infection prevalence at enrollment included chlamydia (16.9%), trichomonas (7.2%), gonorrhea (5.7%), and syphilis (2.2%). External condoms (83.2%) and injectable contraceptives (61.1%) were the methods of contraception most frequently used by participants. In total, through April 3, 2020, 38,490 clinic visits were completed with a retention rate of 96% and 16,807 infusions administered with an adherence rate of 98%.

CONCLUSIONS

This proof-of-concept, large-scale monoclonal antibody study demonstrates the feasibility of conducting complex trials involving intravenous infusions in high incidence populations in sub-Saharan Africa.

Feasibility and Successful Enrollment in a Proof-of-Concept HIV Prevention Trial of VRC01, a Broadly Neutralizing HIV-1 Monoclonal Antibody

BACKGROUND

The Antibody-Mediated Prevention trials (HVTN 704/HPTN 085 and HVTN 703/HPTN 081) are the first efficacy trials to evaluate whether VRC01, a broadly neutralizing monoclonal antibody targeting the CD4-binding site of the HIV envelope protein, prevents sexual transmission of HIV-1. HVTN 704/HPTN 085 enrolled 2701 cisgender men and transgender (TG) individuals who have sex with men at 26 sites in Brazil, Peru, Switzerland, and the United States.

METHODS

Participants were recruited and retained through early, extensive community engagement. Eligible participants were randomized 1:1:1 to 10 mg/kg or 30 mg/kg of VRC01 or saline placebo. Visits occurred monthly, with intravenous (IV) infusions every 8 weeks over 2 years, for a total of 10 infusions. Participants were followed for 104 weeks after first infusion.

RESULTS

The median HVTN 704/HPTN 085 participant age was 28 years; 99% were assigned male sex; 90% identified as cisgender men, 5% as TG women and the remaining as other genders. Thirty-two percent were White, 15% Black, and 57% Hispanic/Latinx. Twenty-eight percent had a sexually transmitted infection at enrollment. More than 23,000 infusions were administered with no serious IV administration complications. Overall, retention and adherence to the study schedule exceeded 90%, and the dropout rate was below 10% annually (7.3 per 100 person-years) through week 80, the last visit for the primary end point.

CONCLUSIONS

HVTN 704/HPTN 085 exceeded accrual and retention expectations. With exceptional safety of IV administration and operational feasibility, it paves the way for future large-scale monoclonal antibody trials for HIV prevention and/or treatment.

Infection- and vaccine-induced antibody binding and neutralization of the B.1.351 SARS-CoV-2 variant

The emergence of SARS-CoV-2 variants with mutations in the spike protein is raising concerns about the efficacy of infection- or vaccine-induced antibodies. We compared antibody binding and live virus neutralization of sera from naturally infected and Moderna-vaccinated individuals against two SARS-CoV-2 variants: B.1 containing the spike mutation D614G and the emerging B.1.351 variant containing additional spike mutations and deletions. Sera from acutely infected and convalescent COVID-19 patients exhibited a 3-fold reduction in binding antibody titers to the B.1.351 variant receptor-binding domain of the spike protein and a 3.5-fold reduction in neutralizing antibody titers against SARS-CoV-2 B.1.351 variant compared to the B.1 variant. Similar results were seen with sera from Moderna-vaccinated individuals. Despite reduced antibody titers against the B.1.351 variant, sera from infected and vaccinated individuals containing polyclonal antibodies to the spike protein could still neutralize SARS-CoV-2 B.1.351, suggesting that protective humoral immunity may be retained against this variant.

Two Randomized Trials of Neutralizing Antibodies to Prevent HIV-1 Acquisition

BACKGROUND

Whether a broadly neutralizing antibody (bnAb) can be used to prevent human immunodeficiency virus type 1 (HIV-1) acquisition is unclear.

METHODS

We enrolled at-risk cisgender men and transgender persons in the Americas and Europe in the HVTN 704/HPTN 085 trial and at-risk women in sub-Saharan Africa in the HVTN 703/HPTN 081 trial. Participants were randomly assigned to receive, every 8 weeks, infusions of a bnAb (VRC01) at a dose of either 10 or 30 mg per kilogram (low-dose group and high-dose group, respectively) or placebo, for 10 infusions in total. HIV-1 testing was performed every 4 weeks. The VRC01 80% inhibitory concentration (IC80) of acquired isolates was measured with the TZM-bl assay.

RESULTS

Adverse events were similar in number and severity among the treatment groups within each trial. Among the 2699 participants in HVTN 704/HPTN 085, HIV-1 infection occurred in 32 in the low-dose group, 28 in the high-dose group, and 38 in the placebo group. Among the 1924 participants in HVTN 703/HPTN 081, infection occurred in 28 in the low-dose group, 19 in the high-dose group, and 29 in the placebo group. The incidence of HIV-1 infection per 100 person-years in HVTN 704/HPTN 085 was 2.35 in the pooled VRC01 groups and 2.98 in the placebo group (estimated prevention efficacy, 26.6%; 95% confidence interval [CI], -11.7 to 51.8; P = 0.15), and the incidence per 100 person-years in HVTN 703/HPTN 081 was 2.49 in the pooled VRC01 groups and 3.10 in the placebo group (estimated prevention efficacy, 8.8%; 95% CI, -45.1 to 42.6; P = 0.70). In prespecified analyses pooling data across the trials, the incidence of infection with VRC01-sensitive isolates (IC80 <1 μg per milliliter) per 100 person-years was 0.20 among VRC01 recipients and 0.86 among placebo recipients (estimated prevention efficacy, 75.4%; 95% CI, 45.5 to 88.9). The prevention efficacy against sensitive isolates was similar for each VRC01 dose and trial; VRC01 did not prevent acquisition of other HIV-1 isolates.

CONCLUSIONS

VRC01 did not prevent overall HIV-1 acquisition more effectively than placebo, but analyses of VRC01-sensitive HIV-1 isolates provided proof-of-concept that bnAb prophylaxis can be effective. (Supported by the National Institute of Allergy and Infectious Diseases; HVTN 704/HPTN 085 and HVTN 703/HPTN 081 ClinicalTrials.gov numbers, NCT02716675 and NCT02568215.).

Reduced binding and neutralization of infection- and vaccine-induced antibodies to the B.1.351 (South African) SARS-CoV-2 variant

The emergence of SARS-CoV-2 variants with mutations in the spike protein is raising concerns about the efficacy of infection- or vaccine-induced antibodies to neutralize these variants. We compared antibody binding and live virus neutralization of sera from naturally infected and spike mRNA vaccinated individuals against a circulating SARS-CoV-2 B.1 variant and the emerging B.1.351 variant. In acutely-infected (5-19 days post-symptom onset), convalescent COVID-19 individuals (through 8 months post-symptom onset) and mRNA-1273 vaccinated individuals (day 14 post-second dose), we observed an average 4.3-fold reduction in antibody titers to the B.1.351-derived receptor binding domain of the spike protein and an average 3.5-fold reduction in neutralizing antibody titers to the SARS-CoV-2 B.1.351 variant as compared to the B.1 variant (spike D614G). However, most acute and convalescent sera from infected and all vaccinated individuals neutralize the SARS-CoV-2 B.1.351 variant, suggesting that protective immunity is retained against COVID-19.

A flexible, pan-species, multi-antigen platform for the detection and monitoring of SARS-CoV-2-specific antibody responses

The SARS-CoV-2 pandemic and the vaccination effort that is ongoing has created an unmet need for accessible, affordable, flexible and precise platforms for monitoring the induction, specificity and maintenance of virus-specific immune responses. Herein we validate a multiplex (Luminex-based) assay capable of detecting SARS-CoV-2-specific antibodies irrespective of host species, antibody isotype, and specimen type (e.g. plasma, serum, saliva or blood spots). The well-established precision of Luminex-based assays provides the ability to follow changes in antibody levels over time to many antigens, including multiple permutations of the most common SARS-CoV-2 antigens. This platform can easily measure antibodies known to correlate with neutralization activity as well as multiple non-SARS-CoV-2 antigens such as vaccines (e.g. Tetanus toxoid) or those from frequently encountered agents (influenza), which serve as stable reference points for quantifying the changing SARS-specific responses. All of the antigens utilized in our study can be made in-house, many in E. coli using readily available plasmids. Commercially sourced antigens may also be incorporated and newly available antigen variants can be rapidly produced and integrated, making the platform adaptable to the evolving viral strains in this pandemic.

COVID-19 Serology at Population Scale: SARS-CoV-2-Specific Antibody Responses in Saliva

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of an ongoing pandemic that has infected over 36 million and killed over 1 million people. Informed implementation of government public health policies depends on accurate data on SARS-CoV-2 immunity at a population scale. We hypothesized that detection of SARS-CoV-2 salivary antibodies could serve as a noninvasive alternative to serological testing for monitoring of SARS-CoV-2 infection and seropositivity at a population scale. We developed a multiplex SARS-CoV-2 antibody immunoassay based on Luminex technology that comprised 12 CoV antigens, mostly derived from SARS-CoV-2 nucleocapsid (N) and spike (S). Saliva and sera collected from confirmed coronavirus disease 2019 (COVID-19) cases and from the pre-COVID-19 era were tested for IgG, IgA, and IgM to the antigen panel. Matched saliva and serum IgG responses (n = 28) were significantly correlated. The salivary anti-N IgG response resulted in the highest sensitivity (100%), exhibiting a positive response in 24/24 reverse transcription-PCR (RT-PCR)-confirmed COVID-19 cases sampled at >14 days post-symptom onset (DPSO), whereas the salivary anti-receptor binding domain (RBD) IgG response yielded 100% specificity. Temporal kinetics of IgG in saliva were consistent with those observed in blood and indicated that most individuals seroconvert at around 10 DPSO. Algorithms employing a combination of the IgG responses to N and S antigens result in high diagnostic accuracy (100%) by as early as 10 DPSO. These results support the use of saliva-based antibody testing as a noninvasive and scalable alternative to blood-based antibody testing.

Quantitative SARS-CoV-2 Serology in Children With Multisystem Inflammatory Syndrome (MIS-C)

OBJECTIVES

We aimed to measure severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serological responses in children hospitalized with multisystem inflammatory syndrome in children (MIS-C) compared with those with coronavirus disease 2019 (COVID-19), those with Kawasaki disease (KD), and hospitalized pediatric controls.

METHODS

From March 17, 2020, to May 26, 2020, we prospectively identified hospitalized children with MIS-C (n = 10), symptomatic COVID-19 (n = 10), and KD (n = 5) and hospitalized controls (n = 4) at Children's Healthcare of Atlanta. With institutional review board approval, we obtained prospective and residual blood samples from these children and measured SARS-CoV-2 spike receptor-binding domain (RBD) immunoglobulin M and immunoglobulin G (IgG), full-length spike IgG, and nucleocapsid protein antibodies using quantitative enzyme-linked immunosorbent assays and SARS-CoV-2 neutralizing antibodies using live-virus focus-reduction neutralization assays. We statistically compared the log-transformed antibody titers among groups and performed linear regression analyses.

RESULTS

All children with MIS-C had high titers of SARS-CoV-2 RBD IgG antibodies, which correlated with full-length spike IgG antibodies (R ² = 0.956; P < .001), nucleocapsid protein antibodies (R ² = 0.846; P < .001), and neutralizing antibodies (R ² = 0.667; P < .001). Children with MIS-C had significantly higher SARS-CoV-2 RBD IgG antibody titers (geometric mean titer 6800; 95% confidence interval 3495-13 231) than children with COVID-19 (geometric mean titer 626; 95% confidence interval 251-1563; P < .001), children with KD (geometric mean titer 124; 95% confidence interval 91-170; P < .001), and hospitalized controls (geometric mean titer 85; P < .001). All children with MIS-C also had detectable RBD immunoglobulin M antibodies, indicating recent SARS-CoV-2 infection. RBD IgG titers correlated with the erythrocyte sedimentation rate (R ² = 0.512; P < .046) and with hospital (R ² = 0.548; P = .014) and ICU lengths of stay (R ² = 0.590; P = .010).

CONCLUSIONS

Quantitative SARS-CoV-2 serology may have a role in establishing the diagnosis of MIS-C, distinguishing it from similar clinical entities, and stratifying risk for adverse outcomes.

Safety and immunogenicity of two heterologous HIV vaccine regimens in healthy, HIV-uninfected adults (TRAVERSE): a randomised, parallel-group, placebo-controlled, double-blind, phase 1/2a study

Background

Bioinformatically designed mosaic antigens increase the breadth of HIV vaccine-elicited immunity. This study compared the safety, tolerability, and immunogenicity of a newly developed, tetravalent Ad26 vaccine with the previously tested trivalent formulation.

Methods

This randomised, parallel-group, placebo-controlled, double-blind, phase 1/2a study (TRAVERSE) was done at 11 centres in the USA and one centre in Rwanda. Eligible participants were adults aged 18 to 50 years, who were HIV-uninfected, healthy at screening based on their medical history and a physical examination including laboratory assessment and vital sign measurements, and at low risk of HIV infection in the opinion of study staff, who applied a uniform definition of low-risk guidelines that was aligned across sites. Enrolled participants were randomly assigned at a 2:1 ratio to tetravalent and trivalent groups. Participants in tetravalent and trivalent groups were then further randomly assigned at a 5:1 ratio to adenovirus 26 (Ad26)-vectored vaccine and placebo subgroups. Randomisation was stratified by region (USA and Rwanda) and based on a computer-generated schedule using randomly permuted blocks prepared under the sponsor's supervision. We masked participants and investigators to treatment allocation throughout the study. On day 0, participants received a first injection of tetravalent vaccine (Ad26.Mos4.HIV or placebo) or trivalent vaccine (Ad26.Mos.HIV or placebo), and those injections were repeated 12 weeks later. At week 24, vaccine groups received a third dose of tetravalent or trivalent together with clade C gp140, and this was repeated at week 48, with placebos again administered to the placebo group. All study vaccines and placebo were administered by intramuscular injection in the deltoid muscle. We assessed adverse events in all participants who received at least one study injection (full analysis set) and Env-specific binding antibodies in all participants who received at least the first three vaccinations according to the protocol-specified vaccination schedule, had at least one measured post-dose blood sample collected, and were not diagnosed with HIV during the study (per-protocol set). This study is registered with Clinicaltrials.gov, NCT02788045.

Findings

Of 201 participants who were enrolled and randomly assigned, 198 received the first vaccination: 110 were in the tetravalent group, 55 in the trivalent group, and 33 in the placebo group. Overall, 185 (93%) completed two scheduled vaccinations per protocol, 180 (91%) completed three, and 164 (83%) completed four. Solicited, self-limiting local, systemic reactogenicity and unsolicited adverse events were similar in vaccine groups and higher than in placebo groups. All participants in the per-protocol set developed clade C Env binding antibodies after the second vaccination, with higher total IgG titres after the tetravalent vaccine than after the trivalent vaccine (10 413 EU/mL, 95% CI 7284–14 886 in the tetravalent group compared with 5494 EU/mL, 3759–8029 in the trivalent group). Titres further increased after the third and fourth vaccinations, persisting at least through week 72. Other immune responses were also higher with the tetravalent vaccine, including the magnitude and breadth of binding antibodies against a cross-clade panel of Env antigens, and the magnitude of IFNγ ELISPOT responses (median 521 SFU/10⁶ peripheral blood mononuclear cells [PBMCs] in the tetravalent group and median 282 SFU/10⁶ PBMCs in the trivalent group after the fourth vaccination) and Env-specific CD4+ T-cell response rates after the third and fourth vaccinations. No interference by pre-existing Ad26 immunity was identified.

Interpretation

The tetravalent vaccine regimen was generally safe, well-tolerated, and found to elicit higher immune responses than the trivalent regimen. Regimens that use this tetravalent vaccine component are being advanced into field trials to assess efficacy against HIV-1 infection.

Funding

National Institutes of Health, Henry M Jackson Foundation for Advancement of Military Medicine and the US Department of Defense, Ragon Institute of MGH, MIT, & Harvard, Bill & Melinda Gates Foundation, and Janssen Vaccines & Prevention.

Systems biological assessment of immunity to mild versus severe COVID-19 infection in humans

Coronavirus disease 2019 (COVID-19) represents a global crisis, yet major knowledge gaps remain about human immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We analyzed immune responses in 76 COVID-19 patients and 69 healthy individuals from Hong Kong and Atlanta, Georgia, United States. In the peripheral blood mononuclear cells (PBMCs) of COVID-19 patients, we observed reduced expression of human leukocyte antigen class DR (HLA-DR) and proinflammatory cytokines by myeloid cells as well as impaired mammalian target of rapamycin (mTOR) signaling and interferon-α (IFN-α) production by plasmacytoid dendritic cells. By contrast, we detected enhanced plasma levels of inflammatory mediators-including EN-RAGE, TNFSF14, and oncostatin M-which correlated with disease severity and increased bacterial products in plasma. Single-cell transcriptomics revealed a lack of type I IFNs, reduced HLA-DR in the myeloid cells of patients with severe COVID-19, and transient expression of IFN-stimulated genes. This was consistent with bulk PBMC transcriptomics and transient, low IFN-α levels in plasma during infection. These results reveal mechanisms and potential therapeutic targets for COVID-19.

Robust antibody and cellular responses induced by DNA-only vaccination for HIV

BACKGROUNDHVTN 098, a randomized, double-blind, placebo-controlled trial, evaluated the safety, tolerability, and immunogenicity of PENNVAX-GP HIV DNA vaccine, administered with or without plasmid IL-12 (pIL-12), via intradermal (ID) or intramuscular (IM) electroporation (EP) in healthy, HIV-uninfected adults. The study tested whether PENNVAX-GP delivered via ID/EP at one-fifth the dose could elicit equivalent immune responses to delivery via IM/EP and whether inclusion of pIL-12 provided additional benefit.METHODSParticipants received DNA encoding HIV-1 env/gag/pol in 3 groups: 1.6 mg ID (ID no IL-12 group, n = 20), 1.6 mg ID + 0.4 mg pIL-12 (ID + IL-12 group, n = 30), 8 mg IM + 1 mg pIL-12 (IM + IL-12 group, n = 30), or placebo (n = 9) via EP at 0, 1, 3, and 6 months. Results of cellular and humoral immunogenicity assessments are reported.RESULTSFollowing vaccination, the frequency of responders (response rate) to any HIV protein based on CD4+ T cells expressing IFN-γ or IL-2 was 96% for both the ID + IL-12 and IM + IL-12 groups; CD8+ T cell response rates were 64% and 44%, respectively. For ID delivery, the inclusion of pIL-12 increased CD4+ T cell response rate from 56% to 96%. The frequency of responders was similar (≥90%) for IgG binding antibody to gp140 consensus Env across all groups, but the magnitude was higher in the ID + IL-12 group compared with the IM + IL-12 group.CONCLUSIONPENNVAX-GP DNA induced robust cellular and humoral immune responses, demonstrating that immunogenicity of DNA vaccines can be enhanced by EP route and inclusion of pIL-12. ID/EP was dose sparing, inducing equivalent, or in some aspects superior, immune responses compared with IM/EP.TRIAL REGISTRATIONClinicalTrials.gov NCT02431767.FUNDINGThis work was supported by National Institute of Allergy and Infectious Diseases (NIAID), U.S. Public Health Service grants, an HIV Vaccine Design and Development Team contract, Integrated Preclinical/Clinical AIDS Vaccine Development Program, and an NIH award.

Duration of Cellular and Humoral Responses after Quadrivalent Human Papillomavirus Vaccination in Healthy Female Adults with or without Prior Type 16 and/or 18 Exposure

Human papillomavirus virus (HPV) vaccines aim to provide durable protection and are ideal to study the association of cellular with humoral responses. We assessed the duration and characteristics of immune responses provided by the quadrivalent HPV (4vHPV) vaccine in healthy female adults with or without prior exposure with type 16 and 18 HPV. In a prospective cohort, vaccine naïve females received three doses of 4vHPV vaccine and were followed for two years to assess cellular (intracellular cytokine staining, proliferation and B cell ELISpot assays) and humoral (multiplex L1/L2 viral-like particles (VLP) and M4 ELISAs) responses. Frequencies of vaccine-specific CD4+ T cells correlated with antibody responses. Higher HPV antibody titers were found at all time points in participants previously exposed to HPV, except for anti-HPV-18 at Day 187 (one week post the third vaccination). Retrospective cohorts enrolled females who had previously received two or three 4vHPV doses and tested antibody titers by M4 ELISA and pseudovirion neutralization assay along with memory B cells (MBCs). Almost all women enrolled in a retrospective cohort with two prior doses and all women enrolled in a retrospective cohort with three prior doses had sustained antibody and memory responses. Our findings indicate that HPV vaccination induces a long-lasting, robust cellular and humoral immune responses.

The receptor binding domain of the viral spike protein is an immunodominant and highly specific target of antibodies in SARS-CoV-2 patients

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that first emerged in late 2019 is responsible for a pandemic of severe respiratory illness. People infected with this highly contagious virus can present with clinically inapparent, mild, or severe disease. Currently, the virus infection in individuals and at the population level is being monitored by PCR testing of symptomatic patients for the presence of viral RNA. There is an urgent need for SARS-CoV-2 serologic tests to identify all infected individuals, irrespective of clinical symptoms, to conduct surveillance and implement strategies to contain spread. As the receptor binding domain (RBD) of the spike protein is poorly conserved between SARS-CoVs and other pathogenic human coronaviruses, the RBD represents a promising antigen for detecting CoV-specific antibodies in people. Here we use a large panel of human sera (63 SARS-CoV-2 patients and 71 control subjects) and hyperimmune sera from animals exposed to zoonotic CoVs to evaluate RBD's performance as an antigen for reliable detection of SARS-CoV-2-specific antibodies. By day 9 after the onset of symptoms, the recombinant SARS-CoV-2 RBD antigen was highly sensitive (98%) and specific (100%) for antibodies induced by SARS-CoVs. We observed a strong correlation between levels of RBD binding antibodies and SARS-CoV-2 neutralizing antibodies in patients. Our results, which reveal the early kinetics of SARS-CoV-2 antibody responses, support using the RBD antigen in serological diagnostic assays and RBD-specific antibody levels as a correlate of SARS-CoV-2 neutralizing antibodies in people.

Rapid Generation of Neutralizing Antibody Responses in COVID-19 Patients

SARS-CoV-2, the virus responsible for COVID-19, is causing a devastating worldwide pandemic, and there is a pressing need to understand the development, specificity, and neutralizing potency of humoral immune responses during acute infection. We report a cross-sectional study of antibody responses to the receptor-binding domain (RBD) of the spike protein and virus neutralization activity in a cohort of 44 hospitalized COVID-19 patients. RBD-specific IgG responses are detectable in all patients 6 days after PCR confirmation. Isotype switching to IgG occurs rapidly, primarily to IgG1 and IgG3. Using a clinical SARS-CoV-2 isolate, neutralizing antibody titers are detectable in all patients by 6 days after PCR confirmation and correlate with RBD-specific binding IgG titers. The RBD-specific binding data were further validated in a clinical setting with 231 PCR-confirmed COVID-19 patient samples. These findings have implications for understanding protective immunity against SARS-CoV-2, therapeutic use of immune plasma, and development of much-needed vaccines.

Cross-sectional study of 44 hospitalized COVID-19 patients

RBD-specific IgG responses detectable in all patients 6 days after PCR confirmation

Neutralizing titers are detectable in all patients 6 days after PCR confirmation

RBD-specific IgG titers correlate with the neutralizing potency

COVID-19 serology at population scale: SARS-CoV-2-specific antibody responses in saliva

Non-invasive SARS-CoV-2 antibody testing is urgently needed to estimate the incidence and prevalence of SARS-CoV-2 infection at the general population level. Precise knowledge of population immunity could allow government bodies to make informed decisions about how and when to relax stay-at-home directives and to reopen the economy. We hypothesized that salivary antibodies to SARS-CoV-2 could serve as a non-invasive alternative to serological testing for widespread monitoring of SARS-CoV-2 infection throughout the population. We developed a multiplex SARS-CoV-2 antibody immunoassay based on Luminex technology and tested 167 saliva and 324 serum samples, including 134 and 118 negative saliva and serum samples, respectively, collected before the COVID-19 pandemic, and 33 saliva and 206 serum samples from participants with RT-PCR-confirmed SARS-CoV-2 infection. We evaluated the correlation of results obtained in saliva vs. serum and determined the sensitivity and specificity for each diagnostic media, stratified by antibody isotype, for detection of SARS-CoV-2 infection based on COVID-19 case designation for all specimens. Matched serum and saliva SARS-CoV-2 antigen-specific IgG responses were significantly correlated. Within the 10-plex SARS-CoV-2 panel, the salivary anti-nucleocapsid (N) protein IgG response resulted in the highest sensitivity for detecting prior SARS-CoV-2 infection (100% sensitivity at ≥10 days post-SARS-CoV-2 symptom onset). The salivary anti-receptor binding domain (RBD) IgG response resulted in 100% specificity. Among individuals with SARS-CoV-2 infection confirmed with RT-PCR, the temporal kinetics of IgG, IgA, and IgM in saliva were consistent with those observed in serum. SARS-CoV-2 appears to trigger a humoral immune response resulting in the almost simultaneous rise of IgG, IgM and IgA levels both in serum and in saliva, mirroring responses consistent with the stimulation of existing, cross-reactive B cells. SARS-CoV-2 antibody testing in saliva can play a critically important role in large-scale "sero"-surveillance to address key public health priorities and guide policy and decision-making for COVID-19.

1272. Feasibility and Successful Enrollment in Proof-of-Concept Trials to Assess Safety and Efficacy of a Broadly Neutralizing Monoclonal Antibody, VRC01, to Prevent HIV-1 Acquisitionin in Uninfected Individuals

Background

The Antibody-mediated Prevention (AMP) trials (HVTN 704/HPTN 085 and HVTN 703/HPTN 081) are the first efficacy trials to evaluate whether VRC01, a broadly neutralizing antibody (bnAb) that targets CD4 binding site of HIV envelope, prevents HIV acquisition in uninfected individuals. In these ongoing trials, 10 intravenous (IV) infusions of VRC01 are given every 8 weeks over a period of 2 years. We report on interim operational feasibility, enrollment and safety.

Methods

Participant recruitment was enhanced by extensive community engagement and education. Eligible participants were randomly assigned 1:1:1 to 10mg/kg, 30mg/kg of VRC01 or saline placebo. HVTN 704/HPTN 085 enrolled high-risk men (MSM) and transgender (TG) individuals who have sex with men at 26 sites in United States, Peru, Brazil, and Switzerland. HVTN 703/HPTN 081 enrolled high-risk heterosexual women at 20 sites in Botswana, Kenya, Malawi, Mozambique, South Africa, Tanzania, and Zimbabwe. HIV testing occurs monthly.

Results

In October 2018, the AMP trials completed enrollment of 4,625 participants. Enrollment met or exceeded targets throughout the trial period, peaked at 298 participants/month, and was slowed mid-trial to allow for sufficient drug supply at trial sites. In HVTN 704/HPTN 085, 2701 (target N = 2700) MSM/TG participants 18–50yrs were enrolled with median age of 28; 99% born male; 90% identified as male gender and 5% TG female. Race/ethnicity was 32% White, 15% Black and 57% Hispanic/Latino/a. 28% had a sexually transmitted infection (STI) including gonorrhea (GC), chlamydia (CT) or syphilis at enrollment. In HVTN 703/HPTN 081,1924 (target N = 1900) women 18–40yrs were enrolled with median age of 26;100% were born female (53% female gender, 47% gender not assessed); 99% were Black. 26% had a STI at enrollment including GC, CT, trichomonas or syphilis. Overall 36,945 infusions have been given so far with no serious procedural complications due to IV administration. Retention and adherence to the rigorous study schedule (monthly visits for 2 years) remain within an acceptable range.

Conclusion

The AMP trials have exceeded enrollment of target populations and are maintaining high rates of retention. With exceptional safety and operational feasibility, they are paving the way for future large-scale bnAb trials for HIV prevention and/or treatment.

Disclosures

All authors: No reported disclosures.

Clinical, Virologic, and Immunologic Characteristics of Zika Virus Infection in a Cohort of US Patients: Prolonged RNA Detection in Whole Blood

Background

Clinical, virologic, and immunologic characteristics of Zika virus (ZIKV) infections in US patients are poorly defined.

Methods

US subjects with suspected ZIKV infection were enrolled. Clinical data and specimens were prospectively collected for ZIKV RNA detection and serologic and cellular assays. Confirmed ZIKV infection (cases) and ZIKV-negative (controls) subjects were compared. Dengue-experienced and dengue-naïve cases were also compared.

Results

We enrolled 45 cases and 14 controls. Commonly reported symptoms among cases and controls were maculopapular rash (97.8% and 81.8%), fatigue (86.7% and 81.8%), and arthralgia (82.2% and 54.5%), respectively. The sensitivity (94%) and duration of infection detection (80% positivity at 65–79 days after disease onset) by polymerase chain reaction were highest in whole-blood specimens. ZIKV-neutralizing antibodies had a half-life of 105 days and were significantly higher in dengue virus–experienced cases than naïve ones (P = .046). In intracellular cytokine staining assays, the ZIKV proteins targeted most often by peripheral blood mononuclear cells from cases were structural proteins C and E for CD4+ T cells and nonstructural proteins NS3, NS5, and NS4B for CD8+ T cells.

Conclusions

ZIKV RNA detection was more frequent and prolonged in whole-blood specimens. Immunoglobulin G (IgG) and neutralizing antibodies, but not IgM, were influenced by prior dengue infection. Robust cellular responses to E and nonstructural proteins have potential vaccine development implications.

2492. Clinical, Virologic, and Immunologic Characteristics of Zika Virus Infection in a Cohort of US Patients

Background

The clinical, virologic and immunologic characteristics of Zika virus (ZIKV) infections in US patients are poorly defined.

Methods

US patients with suspected Zika virus (ZIKV) infection were enrolled and clinical data and specimens were prospectively collected. Body fluids were tested for ZIKV RNA by PCR and blood was tested using serologic and cellular immune assays. Findings from those with confirmed ZIKV infections (cases) and ZIKV-negative controls were compared.

Results

We enrolled 45 cases and 14 controls. The most commonly reported symptoms among cases and controls were maculopapular rash (97.8% and 81.8%), fatigue (86.7% and 81.8%) and arthralgia (82.2% and 54.5%), respectively. The sensitivity and duration of detection by PCR were highest in whole blood samples (94% of 35 cases who had samples collected up to day 79 post illness onset were positive); strikingly, 84% of those were still positive at 65–79 days post illness onset (Figure 1). ZIKV neutralizing antibodies were detected in all cases and none of the controls, and titers were significantly higher in dengue virus (DENV)-experienced subjects than in DENV-naïve ones (Figure 2). Among cases, anti-ZIKV IgG antibodies were also significantly higher in DENV-experienced patients, while anti-ZIKV IgM antibodies were no higher in DENV-experienced compared with naïve ones. Using intracellular cytokine staining, the highest frequencies of T cells producing IFN-γ, IL-2 and/or TNF-α were against the NS1, NS3, and NS5 proteins for CD4+ T cells, and against the E, NS3, and NS5 proteins for CD8+ T cells (Figure 3).

Conclusion

Detection of ZIKV RNA was more frequent and much more prolonged in whole blood samples compared with other body fluids. Diagnostic molecular assays on this easily obtained fluid should be prioritized for point-of-care development. Robust cellular responses to E, NS3 and NS5 proteins could have implications for vaccine development.

Disclosures

R. L. Atmar, Takeda Vaccines, Inc.: Investigator, Research grant.

Safety, tolerability, and immunogenicity of two Zika virus DNA vaccine candidates in healthy adults: randomised, open-label, phase 1 clinical trials

BACKGROUND

The Zika virus epidemic and associated congenital infections have prompted rapid vaccine development. We assessed two new DNA vaccines expressing premembrane and envelope Zika virus structural proteins.

METHODS

We did two phase 1, randomised, open-label trials involving healthy adult volunteers. The VRC 319 trial, done in three centres, assessed plasmid VRC5288 (Zika virus and Japanese encephalitis virus chimera), and the VRC 320, done in one centre, assessed plasmid VRC5283 (wild-type Zika virus). Eligible participants were aged 18-35 years in VRC19 and 18-50 years in VRC 320. Participants were randomly assigned 1:1 by a computer-generated randomisation schedule prepared by the study statistician. All participants received intramuscular injection of 4 mg vaccine. In VRC 319 participants were assigned to receive vaccinations via needle and syringe at 0 and 8 weeks, 0 and 12 weeks, 0, 4, and 8 weeks, or 0, 4, and 20 weeks. In VRC 320 participants were assigned to receive vaccinations at 0, 4, and 8 weeks via single-dose needle and syringe injection in one deltoid or split-dose needle and syringe or needle-free injection with the Stratis device (Pharmajet, Golden, CO, USA) in each deltoid. Both trials followed up volunteers for 24 months for the primary endpoint of safety, assessed as local and systemic reactogenicity in the 7 days after each vaccination and all adverse events in the 28 days after each vaccination. The secondary endpoint in both trials was immunogenicity 4 weeks after last vaccination. These trials are registered with ClinicalTrials.gov, numbers NCT02840487 and NCT02996461.

FINDINGS

VRC 319 enrolled 80 participants (20 in each group), and VRC 320 enrolled 45 participants (15 in each group). One participant in VRC 319 and two in VRC 320 withdrew after one dose of vaccine, but were included in the safety analyses. Both vaccines were safe and well tolerated. All local and systemic symptoms were mild to moderate. In both studies, pain and tenderness at the injection site was the most frequent local symptoms (37 [46%] of 80 participants in VRC 319 and 36 [80%] of 45 in VRC 320) and malaise and headache were the most frequent systemic symptoms (22 [27%] and 18 [22%], respectively, in VRC 319 and 17 [38%] and 15 [33%], respectively, in VRC 320). For VRC5283, 14 of 14 (100%) participants who received split-dose vaccinations by needle-free injection had detectable positive antibody responses, and the geometric mean titre of 304 was the highest across all groups in both trials.

INTERPRETATION

VRC5283 was well tolerated and has advanced to phase 2 efficacy testing.

FUNDING

Intramural Research Program of the Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health.

Innate, T-, and B-Cell Responses in Acute Human Zika Patients

Background

There is an urgent need for studies of viral persistence and immunity during human Zika infections to inform planning and conduct of vaccine clinical trials.

Methods

In 5 returned US travelers with acute symptomatic Zika infection, clinical features, viral RNA levels, and immune responses were characterized.

Results

Two pregnant, flavivirus-experienced patients had viral RNA persist in plasma for >44 and >26 days. Three days after symptom onset, transient increases in proinflammatory monocytes began followed at 5 days by transient decreases in myeloid dendritic cells. Anti-Zika virus immunoglobulin M was detected at day 7 after symptom onset, persisted beyond 103 days, and remained equivocal through day 172. Zika virus-specific plasmablasts and neutralizing antibodies developed quickly; dengue virus-specific plasmablasts and neutralizing antibodies at high titers developed only in flavivirus-experienced patients. Zika virus- and dengue virus-specific memory B cells developed in both flavivirus-naive and -experienced patients. CD4+ T cells were moderately activated and produced antiviral cytokines after stimulation with Zika virus C, prM, E, and NS5 peptides in 4/4 patients. In contrast, CD8+ T cells were massively activated, but virus-specific cells that produced cytokines were present in only 2/4 patients assessed.

Conclusions

Acute infections with Zika virus modulated antigen-presenting cell populations early. Flavivirus-experienced patients quickly recalled cross-reactive MBCs to secrete antibodies. Dengue virus-naive patients made little dengue-specific antibody but developed MBCs that cross-reacted against dengue virus. Zika virus-specific functional CD4+ T cells were readily detected, but few CD8+ T cells specific for the tested peptides were found.