Faculty Bibliography

SARS-CoV-2 infection is associated with platelet hyperreactivity and increased rates of arterial and venous thrombosis. SARS-CoV-2 mutations have resulted in several variants with differences in transmissibility, infectivity, and patient outcomes. This study investigates the effects of the ancestral strain of SARS-CoV-2 (WA1) and two variants of concern, Delta and Omicron, on the human megakaryocyte (MK) phenotype and transcriptome. Human CD34⁺-derived MKs were incubated with WA1, Delta or Omicron SARS-CoV-2 variants for 24 hours. MK activation markers were measured under resting and thrombin-stimulated conditions. RNA-seq and cytokine release in response to the viruses were assessed. Plasma cytokines were measured in hospitalized COVID-19 patients. Treatment of MKs with WA1, Delta or Omicron variants of SARS-CoV-2 resulted in similar increases in classical activation markers. However, SARS-CoV-2 variants mediated distinct transcriptomic changes. Across variants, 60 genes overlapped, including CXCL8. Consistent with transcriptomic changes, SARS-CoV-2-incubated MKs secreted significantly elevated levels of IL-8. Among hospitalized COVID-19 patients, plasma IL-8 levels were highest in COVID-19 patients who subsequently experienced thrombotic events or died. In conclusion, WA1, Delta, and Omicron similarly induce classical MK activation responses while mediating distinct transcriptomic changes. Increased IL-8 levels may serve as a biomarker to inform platelet hyperreactivity and thrombotic events associated with COVID-19.

Snow Mountain Virus (SMV), the prototype of genogroup II and genotype II Norovirus (NoV), was used in human challenge studies to examine the infectivity, pathogenicity, and immune response to NoV. Clinical and laboratory data from two previously completed SMV human challenge trials using two different inocula (primary and secondary) were analyzed to compare the infectivity, illness, viral shedding, and serum IgG conversion. The primary and secondary SMV inocula were sequenced for detecting single nucleotide mutations. Of 15 subjects challenged with the primary inoculum between 2000 and 2002, nine were infected, and seven presented with acute gastroenteritis. Of 33 subjects challenged with the secondary inoculum between 2016 and 2018, 25 were infected, and nine presented with acute gastroenteritis. There were no statistically significant differences in overall infection and illness rates between subjects challenged with the primary inoculum versus the secondary inoculum. However, subjects infected with the primary inoculum experienced more severe clinical symptoms of acute gastroenteritis, showing higher severity scores (6.00 vs. 2.94, p = 0.003) compared with those infected with the secondary inoculum. We also observed that infection with the secondary inoculum resulted in longer viral shedding compared with the primary inoculum. Partial sequencing of the SMV genome identified three mutations in both inocula. Understanding the differences between these two SMV inocula is critical for NoV vaccine evaluation and using a less pathogenic inoculum for a vaccine trial will require more participants to meet the target reduction in illness when evaluating the efficacy of candidate vaccines.

BACKGROUND AND OBJECTIVE/OBJECTIVE:We describe the kinetics of maternally derived antibodies in infants in the first 6 months of life following 2- or 3-dose maternal vaccination during pregnancy or postpartum. METHODS:This prospective, multicenter cohort study enrolled infants born to mothers vaccinated with 2- (n = 280) or 3-dose (boosted) monovalent messenger RNA vaccines in pregnancy (n = 202) or to mothers vaccinated postpartum (n = 36) from July 2021 to January 2022. Binding (immunoglobulin G to S and receptor-binding domain), pseudovirus, and live neutralizing antibody (nAb) geometric mean titers (GMTs) to vaccine and Omicron BA.1/BA.5 strains were measured at birth and 2 and 6 months of age. Antibody half-life and the effect of maternal or infant COVID-19 infection were assessed. RESULTS:Significantly higher GMTs of binding antibody and nAb to all antigens were present at birth and 2 months in infants of boosted mothers (P < .01) and higher titers to the vaccine strain, but not Omicron BA.1 and BA.5, persisted up to 6 months of age in infants of boosted mothers compared with the other groups (P < .01). Higher infant antibody titers at delivery and 6 months of age were associated with a booster dose during pregnancy and maternal prenatal and infant COVID-19 infection. Maternal infection status or vaccine regimen did not influence the half-life of infant antibodies. CONCLUSIONS:A maternal COVID-19 booster in pregnancy results in significantly higher functional antibody titers in infants compared with 2 doses in pregnancy or postpartum. High titers at birth and maternal hybrid immunity result in persistently elevated titers in infants for 6 months.

BACKGROUND:Mucosal immunity plays a critical role in preventing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and replication. Understanding the capacity of coronavirus disease 2019 (COVID-19) vaccines to elicit both mucosal and systemic antibodies could help optimize vaccination strategies. METHODS:We conducted an open-label, phase 1/2 adaptive-design clinical trial to evaluate the safety and immunogenicity of COVID-19 immunizations. Healthy adults received 2 priming doses of mRNA-1273, a booster dose of mRNA-1273, and a second booster of bivalent (WA-1 and BA.4/BA.5) mRNA-1273.222. Adverse event data were collected. Serum and mucosal immunity were evaluated. RESULTS:One hundred six persons were enrolled. Thirty received all 4 study-related vaccine doses. All vaccines were well tolerated, with injection site pain, malaise, myalgias, and headache being the most frequently reported symptoms. Among those who received a second booster, 24 of 30 (80%) had serological evidence of SARS-CoV-2 infection. Following the second booster, increases in geometric mean binding and pseudovirus neutralization antibody titers to the ancestral strain and BA.1 and BA.5 variants were observed. Increases in mucosal immunoglobulin G and immunoglobulin A (IgA) antibodies in nasal and salivary samples were observed in both previously infected and infection-naive participants, although prior infection markedly boosted virus-specific mucosal IgA responses. CONCLUSIONS:The mRNA-1273.222 booster vaccine was safe and immunogenic and induced mucosal antibody responses in previously infected and infection-naive persons. CLINICAL TRIALS REGISTRATION/BACKGROUND:NCT04889209.

UNLABELLED:The 2022 global outbreak of clade IIb mpox was the first major outbreak of mpox outside of African nations. To control the outbreak, public health officials began vaccination campaigns using the third-generation orthopoxvirus vaccine modified vaccinia Ankara from Bavarian Nordic (MVA-BN). Prior to this outbreak, the durability of monkeypox virus (MPXV)-specific immunity induced by MVA-BN was poorly understood. In 2022, we launched the New York City Observational Study of Mpox Immunity (NYC OSMI, NCT05654883), a longitudinal study of 171 participants comprising MVA-BN vaccines and mpox convalescent individuals. Peripheral blood sampling was performed at intervals including prior to vaccination, after one dose, and after the second dose. MVA-BN vaccinees with and without a history of smallpox vaccination demonstrated detectable MPXV-specific memory B cells at 1-year post-vaccination. Additionally, MVA-BN increased MPXV neutralizing titers in smallpox vaccine-naïve vaccinees, with a comparable maximum titer reached in naïve and smallpox vaccine-experienced vaccinees. However, neutralizing titers returned to baseline within 5-7 months for naïve individuals, while remaining elevated in those with prior smallpox vaccination. Both naïve and experienced individuals generated robust IgG responses against MPXV H3 and A35, but naïve vaccinees' IgG responses showed lower avidity than experienced vaccinees. These data highlight a low avidity antibody response elicited by MVA-BN that is short-lived in naïve vaccinees. This work supports the need for long-term studies on protection induced by MVA-BN, including the potential need for booster doses as well as the development of next-generation orthopoxvirus vaccines. IMPORTANCE/OBJECTIVE:The ongoing outbreaks of mpox demonstrate the continuing threat of orthopoxviruses to global health. While previous orthopoxvirus vaccines generated lifelong antibody and cellular immunity, we show here that the current mpox vaccine, MVA-BN or JYNNEOS, fails to induce durable antibody immunity in individuals with no prior smallpox vaccination. This raises the important question of whether MVA-BN vaccinees have long-term protection from mpox. Our work highlights the need for further studies into the durability of protection generated by MVA-BN as well as whether subsequent booster doses are necessary to maintain protection.

We performed a systems vaccinology analysis to investigate immune responses in humans to an H5N1 influenza vaccine, with and without the AS03 adjuvant, to identify factors influencing antibody response magnitude and durability. Our findings revealed a platelet and adhesion-related blood transcriptional signature on day 7 that predicted the longevity of the antibody response, suggesting a potential role for platelets in modulating antibody response durability. As platelets originate from megakaryocytes, we explored the effect of thrombopoietin (TPO)-mediated megakaryocyte activation on antibody response longevity. We found that TPO administration enhanced the durability of vaccine-induced antibody responses. TPO-activated megakaryocytes also promoted survival of human bone-marrow plasma cells through integrin β1/β2-mediated cell-cell interactions, along with survival factors APRIL and the MIF-CD74 axis. Using machine learning, we developed a classifier based on this platelet-associated signature, which predicted antibody response longevity across six vaccines from seven independent trials, highlighting a conserved mechanism for vaccine durability.

BACKGROUND:Following maternal COVID-19 vaccination, the persistence of antibodies in sera and breast milk for mothers and infants is not well characterized. We sought to describe the persistence of antibodies through 2 months after delivery in maternal and infant serum and breast milk following maternal COVID-19 mRNA vaccination and to examine differences by receipt of booster dose during pregnancy or postpartum. METHODS:This is a prospective cohort study with enrollment from July 2021 to January 2022 at 9 US academic sites. Pregnant or postpartum participants and their infants were enrolled after COVID-19 mRNA monovalent vaccination during pregnancy (primary 2-dose series) with booster (third dose) vaccination during pregnancy or within 2 months post-partum. SARS-CoV-2-binding and functional antibody responses at delivery and 2 months after delivery in mothers and infants were measured by spike and receptor-binding domain immunoglobulin (Ig) G, pseudovirus and live neutralizing antibody (nAb) titers to ancestral and Omicron BA.1 and BA.5 strains. Breast milk spike and receptor-binding domain IgG and IgA titers were also measured. RESULTS:A total of 237 maternal/infant dyads were included (110 primary series during pregnancy, 99 pregnancy booster and 28 postpartum booster). A pregnancy booster resulted in 2.2-4.7-fold higher IgG and nAb at delivery and 2 months for both mothers and infants compared to the primary series alone (P < 0.001 for all comparisons). While infant IgG and nAb titers decreased by 2 months of age, the proportion of infants with detectable nAb at 2 months was greater in infants of mothers boosted during pregnancy compared with primary series for all variants (D614G: 99% vs. 56%; BA.1: 56% vs. 4% and BA.5: 57% vs. 9%; P < 0.001 for all comparisons). Breast milk spike IgA and IgG were present in 64%-100% and 100% of participants, respectively, and those boosted during pregnancy or postpartum had 3.1-4.6-fold higher levels of breast milk antibodies at 2 months compared to primary series during pregnancy (P < 0.001). CONCLUSIONS:mRNA COVID-19 monovalent booster vaccination during pregnancy results in significantly higher maternal and infant serum-binding IgG and nAb titers compared to a primary 2-dose series, including against Omicron variants, through 2 months of age. Breast milk antibodies following maternal vaccination during pregnancy or postpartum may provide additional protection during early infancy.

BACKGROUND:Rabies is a zoonotic viral encephalitis that is endemic in many countries and confers a high mortality. Licensed vaccines require several doses to ensure efficacy. To investigate a logistically favorable approach, we assessed the safety and immunogenicity of ChAd155-RG, a novel investigational rabies vaccine using a replication-defective chimpanzee adenovirus vector. METHODS:We conducted a first-in-human, phase 1, randomized, double-blind, dose-escalation trial comparing ChAd155-RG with a licensed inactivated vaccine (RabAvert) in healthy adults. Participants received either RabAvert at standard dosing or ChAd155-RG at a low dose for one immunization or a high dose for one or two immunizations. To assess safety, we evaluated reactogenicity, unsolicited adverse events, and thrombotic events. To measure immunogenicity, we measured rabies viral neutralizing antibody (VNA) titers and anti-ChAd155 neutralizing antibodies. RESULTS:Mild to moderate systemic reactogenicity and transient lymphopenia and neutropenia were more common among recipients of ChAd155-RG compared with those who received RabAvert. No thrombotic events or serious adverse events were reported. Only the groups receiving RabAvert or two doses of high-dose ChAd155-RG achieved 100 % seroconversion, and seroprotection was most durable in the RabAvert group. Most participants had preexisting anti-vector antibodies, which were boosted by ChAd155-RG. Baseline and post-vaccination anti-vector antibody titers were negatively associated with post-vaccination rabies VNA titers. CONCLUSIONS:In this phase 1 clinical trial, a novel rabies vaccine using a simian adenovirus vector was safe and tolerable, but generated lower, less durable rabies VNA titers than a standard inactivated rabies virus vaccine, which may be due to preexisting, anti-vector immunity.

BACKGROUND:rVSVΔG-ZEBOV-GP is the first approved vaccine with clinical efficacy against Ebola virus disease. Although a seroprotective threshold has not been defined for those at occupational risk of exposure, the current vaccine strategy is to attain a sustained high level of antibody titres. The aim of this trial was to explore the effects of delayed boosting upon both the height and duration of antibody titres following primary immunisation. METHODS:plaque-forming unit per mL of VSVΔG-ZEBOV-GP. 18 months later, individuals who consented and were still eligible were randomly assigned 1:1 to receive either a homologous booster dose or no booster. Study visits for safety and serial blood collections for antibody titres were done on enrolled participants at months 0, 1, 3, 6, 12, 18, 19, 24, 30, and 36. Through July, 2021, a web-based application was used for randomisation, including assignments with schedules for each of the five sites using mixed permuted blocks. The trial was not masked to participants or site staff. The primary endpoint was a comparison of geometric mean titres (GMTs) of anti-Ebola virus glycoprotein IgG antibody at month 36 (ie, 18 months after randomisation) for all randomly assigned participants who completed the 36 months of follow-up (primary analysis cohort). Investigators were aware of antibody titres from baseline (enrolment) through month 18 but were masked to summary data by randomisation group after month 18. This study is registered with ClinicalTrials.gov (NCT02788227). FINDINGS/RESULTS:Of the 248 participants who enrolled and received their primary immunisation, 114 proceeded to the randomisation step at month 18. The two randomisation groups were balanced: 57 participants (24 [42%] of whom were female; median age was 42 years [IQR 35-50]) were randomly assigned to the booster group and 57 (24 [42%] of whom were female; median age was 42 years [IQR 36-51]) to the no-booster group. Of those randomly assigned, 92 participants (45 in the booster group and 47 in the no-booster group) completed 36 months of follow-up. At 18 months after primary immunisation, GMTs in the no-booster group increased from a baseline of 10 ELISA units (EU)/mL (95% CI 7-14) to 1451 EU/mL (1118-1882); GMTs in the booster group increased from 9 EU/mL (6-16) to 1769 EU/mL (1348-2321). At month 19, GMTs were 31 408 EU/mL (23 181-42 554) for the booster group and 1406 EU/mL (1078-1833) for the no-booster group; at month 36, GMTs were 10 146 EU/mL (7960-12 933) for the booster group and 1240 EU/mL (984-1563) for the no-booster group. Accordingly, the geometric mean ratio (GMR) of antibody titres had increased almost 21-fold more in the booster versus no-booster group at 1 month after booster administration (GMR 20·6; 95% CI 18·2-23·0; p<0·0001) and was still over 7-fold higher at month 36 (GMR 7·8; 95% CI 5·5-10·2; p<0·0001). Consistent with previous reports of this vaccine's side-effects, transient mono-articular or oligo-articular arthritis was diagnosed in 18 (9%) of 207 primary vaccination recipients; after randomisation, arthritis was diagnosed in one (2%) of 57 participants in the no-booster group. No new cases of arthritis developed after booster administration. Four serious adverse events occurred following randomisation: one (epistaxis) in the booster group and three (gastrointestinal haemorrhage, prostate cancer, and tachyarrhythmia) in the no-booster group. None of the serious adverse events was judged attributable to the booster vaccination assignment. INTERPRETATION/CONCLUSIONS:In addition to no new safety concerns and in marked contrast to earlier trials evaluating short-term boosting, delaying a rVSVΔG-ZEBOV-GP booster until month 18 resulted in an increase in GMT that remained several-fold above the no-booster group GMT for at least 18 months. These findings could have implications for defining the optimal timing of booster doses as pre-exposure prophylaxis in populations at ongoing risk for Ebola virus exposure. FUNDING/BACKGROUND:The Division of Intramural Research and the Division of Clinical Research of the National Institute of Allergy and Infectious Diseases at the US National Institutes of Health, Canadian Immunization Research Network through the Public Health Agency of Canada, Canadian Institutes of Health Research, and the US Defense Threat Reduction Agency.