Biology subjects

Hederman, A. P.

Publications and source records attributed to Hederman, A. P..

4 recordsLinked to original sources

bioRxiv2026

Late induction of IgG4 following SARS-CoV-2 mRNA vaccination in pregnant and non-pregnant individuals includes clonotypes raised early in the response

To better understand how pregnancy impacts humoral immunity, we conducted an in-depth longitudinal analysis of the kinetics and characteristics of vaccine responses in a prospective cohort of pregnant and non-pregnant women. Humoral immune responses observed among pregnant participants who received the mRNA-delivered SARS-CoV-2 vaccination, including their effector functions, were in some cases marginally lower than those among non-pregnant controls, while prior infection was associated with some potentiation in humoral responses. Importantly, vaccine-induced antibodies were efficiently transferred across the placenta, providing the fetus with passive immunity and underscoring the dual benefit of maternal vaccination for both mother and neonate against COVID-19. Delayed induction of spike-specific IgG4 following the primary two-dose vaccination series was observed in vaccine recipients, independent of pregnancy status. In a subset (n=6) of pregnant women whose spike-specific serum IgG repertoires were extensively profiled at the clonotypic level over time as part of another study, we proteomically identified secreted IgG clonotypes that had class-switched to IgG4. Matching of these clonotypes detected as IgG4 to those defined as SARS-CoV-2 spike-specific revealed that, while a minority of total clonotypes, they were elicited early in the immunization series and tended to be more highly mutated, more prevalent, and more persistent than clonotypes in the serological repertoire that were not detected as IgG4. Consistent with the increase in secreted vaccine-specific IgG4 over time, but its poorer placental transfer, these clonotypes were detected at greater levels in maternal but not cord blood at the time of delivery as compared to 28 days post the second vaccine dose. These findings indicate some impact in the kinetics, characteristics, and functions of the humoral response that may be associated with pregnancy-related immune modulation. Conservation of the late class-switch recombination to IgG4 that has previously been associated with mRNA-based SARS-CoV-2 vaccines raises questions about how different immunological states and vaccine components influence short- and long-term characteristics of the humoral immune response.

immunology↗

bioRxiv2026

Convergent strategies for nanobody-mediated inhibition of an epoxide hydrolase

Secreted by Pseudomonas aeruginosa, Cif is an epoxide hydrolase that acts as a virulence factor in the context of cystic fibrosis and thus represents a target for therapeutic inhibition. Here, we present the structures of several high-affinity inhibitory nanobodies, each bound to Cif. Comparison reveals two classes of nanobodies with distinct CDR sequences and convergent recognition strategies. Mimicry between CDR3 and CDR2 loops positions an aromatic residue for insertion through the active-site gate, accessing a cryptic epitope, which sterically blocks substrate access and provides an anchor point for high-affinity engagement. Projection of either inhibitory CDR toward the active-site entrance requires a relative 90{degrees} rotation of the core immunoglobulin domain, and yet both classes engage the same set of stereochemical handholds within a highly overlapping shared epitope. The structurally distinct paratopes thus represent fundamentally distinct solutions, reflecting the remarkable capacity of the immune system to solve highly constrained molecular recognition challenges.

biochemistry↗

bioRxiv2023

Characterization of SARS-CoV-2 Convalescent Patients' Serological Repertoire Reveals High Prevalence of Iso-RBD Antibodies

While our understanding of SARS-CoV-2 pathogenesis and antibody responses following infection and vaccination has improved tremendously since the outbreak in 2019, the sequence identities and relative abundances of the individual constituent antibody molecules in circulation remain understudied. Using Ig-Seq, we proteomically profiled the serological repertoire specific to the whole ectodomain of SARS-CoV-2 prefusion-stabilized spike (S) as well as to the receptor binding domain (RBD) over a 6-month period in four subjects following SARS-CoV-2 infection before SARS-CoV-2 vaccines were available. In each individual, we identified between 59 and 167 unique IgG clonotypes in serum. To our surprise, we discovered that [~]50% of serum IgG specific for RBD did not recognize prefusion-stabilized S (referred to as iso-RBD antibodies), suggesting that a significant fraction of serum IgG targets epitopes on RBD inaccessible on the prefusion-stabilized conformation of S. On the other hand, the abundance of iso-RBD antibodies in nine individuals who received mRNA-based COVID-19 vaccines encoding prefusion-stabilized S was significantly lower ([~]8%). We expressed a panel of 12 monoclonal antibodies (mAbs) that were abundantly present in serum from two SARS-CoV-2 infected individuals, and their binding specificities to prefusion-stabilized S and RBD were all in agreement with the binding specificities assigned based on the proteomics data, including 1 iso-RBD mAb which bound to RBD but not to prefusion-stabilized S. 2 of 12 mAbs demonstrated neutralizing activity, while other mAbs were non-neutralizing. 11 of 12 mAbs also bound to S (B.1.351), but only 1 maintained binding to S (B.1.1.529). This particular mAb binding to S (B.1.1.529) 1) represented an antibody lineage that comprised 43% of the individuals total S-reactive serum IgG binding titer 6 months post-infection, 2) bound to the S from a related human coronavirus, HKU1, and 3) had a high somatic hypermutation level (10.9%), suggesting that this antibody lineage likely had been elicited previously by pre-pandemic coronavirus and was re-activated following the SARS-CoV-2 infection. All 12 mAbs demonstrated their ability to engage in Fc-mediated effector function activities. Collectively, our study provides a quantitative overview of the serological repertoire following SARS-CoV-2 infection and the significant contribution of iso-RBD antibodies, demonstrating how vaccination strategies involving prefusion-stabilized S may have reduced the elicitation of iso-RBD serum antibodies which are unlikely to contribute to protection.

immunology↗

bioRxiv2021

Engineered ACE2-Fc counters murine lethal SARS-CoV-2 infection through direct neutralization and Fc-effector activities

Soluble Angiotensin-Converting Enzyme 2 (ACE2) constitutes an attractive antiviral capable of targeting a wide range of coronaviruses utilizing ACE2 as their receptor. Here, using structure-guided approaches, we developed divalent ACE2 molecules by grafting the extracellular ACE2-domain onto a human IgG1 or IgG3 (ACE2-Fc). These ACE2-Fcs harbor structurally validated mutations that enhance spike (S) binding and remove angiotensin enzymatic activity. The lead variant bound tightly to S, mediated in vitro neutralization of SARS-CoV-2 variants of concern (VOCs) with sub-nanomolar IC50 and was capable of robust Fc-effector functions, including antibody-dependent-cellular cytotoxicity, phagocytosis and complement deposition. When tested in a stringent K18-hACE2 mouse model, it delayed death or effectively resolved lethal SARS-CoV-2 infection in a prophylactic or therapeutic setting utilizing the combined effect of neutralization and Fc-effector functions. These data confirm the utility of ACE2-Fcs as valuable agents in preventing and eliminating SARS-CoV-2 infection and demonstrate that ACE2-Fc therapeutic activity require Fc-effector functions.

microbiology↗