Faculty Bibliography

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.

The T300A substitution in ATG16L1 associated with Crohn's disease impairs autophagy, yet up to 50% of humans are heterozygous for this allele. Here, we demonstrate that heterozygosity for the analogous substitution in mice (Atg16L1^T316A), but not homozygosity, protects against lethal Salmonella enterica Typhimurium infection. One copy of Atg16L1^T316A was sufficient to enhance cytokine production through inflammasome activation, which was necessary for protection. In contrast, two copies of Atg16L1^T316A inhibited the autophagy-related process of LC3-associated phagocytosis (LAP) and increased susceptibility. Macrophages from human donors heterozygous for ATG16L1^T300A displayed elevated inflammasome activation while homozygosity impaired LAP, similar to mice. These results clarify how the T300A substitution impacts ATG16L1 function and suggest it can be beneficial to heterozygous carriers, providing an explanation for its prevalence within the human population.

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.

Gastrointestinal (GI) colonization by methicillin-resistant Staphylococcus aureus (MRSA) is associated with a high risk of transmission and invasive disease in vulnerable populations. The immune and microbial factors that permit GI colonization remain unknown. Male sex is correlated with enhanced Staphylococcus aureus nasal carriage, skin and soft tissue infections, and bacterial sepsis. Here, we established a mouse model of sexual dimorphism during GI colonization by MRSA. Our results show that in contrast to male mice that were susceptible to persistent colonization, female mice rapidly cleared MRSA from the GI tract following oral inoculation in a manner dependent on the gut microbiota. This colonization resistance displayed by female mice was mediated by an increase in IL-17A+ CD4+ T cells (Th17) and dependent on neutrophils. Ovariectomy of female mice increased MRSA burden, but gonadal female mice that have the Y chromosome retained enhanced Th17 responses and colonization resistance. Our study reveals a novel intersection between sex and gut microbiota underlying colonization resistance against a major widespread pathogen.

BACKGROUND/UNASSIGNED:Global study data show injection drug use is driving upwards of 79% of all new hepatitis C virus (HCV) cases in high-income countries. Low-threshold models can engage vulnerable populations in treatment to achieve HCV elimination targets. We examined the implementation of low-threshold models for HCV care in New York State, which has a robust HCV elimination program. METHODS/UNASSIGNED:We conducted semi-structured interviews with 16 healthcare providers in 2022. Included providers either self-described as "low-threshold," had a clinical focus on marginalized populations, or practiced in non-traditional settings. Interviews focused on the implementation of low-threshold HCV care. Transcripts were analyzed using thematic analysis and were categorized into themes guided by the Exploration, Preparation, Implementation, Sustainment (EPIS) framework. RESULTS/UNASSIGNED:Providers implemented low-threshold HCV care by facilitating access (e.g., having walk-in or telemedicine HCV services). Point-of-care testing and peer support were other important features. The inner context was driven by provider and organization values and involved providing low-threshold HCV care within health systems that were not themselves "low-threshold." Adequate staffing was crucial for the extensive care coordination and outreach activities needed to engage persons who inject drugs (PWID). The outer context was characterized by a limited funding environment, restrictive insurance policies, and the high impact of patients' unmet social needs. Providers relied on care coordination and integrated care models to overcome these barriers. CONCLUSIONS/UNASSIGNED:Low-threshold HCV care incorporates operational flexibility and patient navigation but is challenged by patients' unmet social needs. Jurisdictions can support implementation by providing adequate funding for substantial outreach activities needed to engage vulnerable populations.

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.

Pathogenic Enterobacter species are of increasing clinical concern due to the multidrug-resistant nature of these bacteria, including resistance to carbapenem antibiotics. Our understanding of Enterobacter virulence is limited, hindering the development of new prophylactics and therapeutics targeting infections caused by Enterobacter species. In this study, we assessed the virulence of contemporary clinical Enterobacter hormaechei isolates in a mouse model of intraperitoneal infection and used comparative genomics to identify genes promoting virulence. Through mutagenesis and complementation studies, we found two porin-encoding genes, ompC and ompD, to be required for E. hormaechei virulence. These porins imported clinically relevant carbapenems into the bacteria, and thus loss of OmpC and OmpD desensitized E. hormaechei to the antibiotics. Our genomic analyses suggest porin-related genes are frequently mutated in E. hormaechei, perhaps due to the selective pressure of antibiotic therapy during infection. Despite the importance of OmpC and OmpD during infection of immunocompetent hosts, we found the two porins to be dispensable for virulence in a neutropenic mouse model. Moreover, porin loss provided a fitness advantage during carbapenem treatment in an ex vivo human whole blood model of bacteremia. Our data provide experimental evidence of pathogenic Enterobacter species gaining antibiotic resistance via loss of porins and argue antibiotic therapy during infection of immunocompromised patients is a conducive environment for the selection of porin mutations enhancing the multidrug-resistant profile of these pathogens.

BACKGROUND:Bloodstream infections (BSI) are associated with high mortality rates, particularly when caused by resistant pathogens. Reducing the delay in diagnosis and initiation of appropriate treatment is crucial for improving clinical outcomes. The implementation of polymerase chain reaction (PCR) tests in the diagnostic process offers a promising approach to achieving quicker identification of pathogens, thereby potentially reducing mortality associated with BSI. METHODS:BSI, for which diagnostic protocol has been unchanged. RESULTS:(VRE) BSI and 384 with MSSA BSI. The mean 30-day mortality risk difference in the period post-intervention estimated in our difference-in-differences model was -6.03 per 100 (95% CI: -10.35 to -1.7), with event study plots suggesting minimal deviation from parallel trends in the pre-treatment period. CONCLUSIONS:Findings suggest that introduction of BCID2 PCR testing for enterococcal bloodstream infections (BSI) may be associated with a reduction in mortality, however, interpretation of the effects must be approached with caution given the relative imprecision of estimates. Further research with larger samples is essential to establish a definitive conclusion on the impact of rapid PCR testing on mortality in BSI. This is an innovative approach using causal methods to evaluate interventions aimed at the improvement of infection control and antimicrobial treatment strategies.

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.