Biology subjects

Marchant, A.

Publications and source records attributed to Marchant, A..

4 recordsLinked to original sources

bioRxiv2026

Systematic Evaluation of Nasal Immune Cell Sampling and Antigen-specific T cell Detection using Cryopreserved Nasal Swabs

The upper respiratory tract is a key entry point for pathogens, yet local tissue-resident memory T cells (Trm) remain underexplored compared to peripheral blood. We systematically compared nasal curettes and 8 different swab types for immune cell collection, assessing yield, operator variability, and T cell phenotypes across the three turbinates and nasopharynx. The use of flocked swabs yielded higher immune cell numbers while being similarly tolerated, especially with reduced sampling duration. Nasal Trm subsets were consistent across the turbinates, whereas nasopharyngeal Trm displayed a more recently recruited phenotype. Multiple cryopreservation media were evaluated and all demonstrated high viability after thawing. Antigen-specificity was assessed using the activation induced marker (AIM) assay, peptideHLA tetramers and bulk TCR-sequencing following expansion. Notably, influenza-specific T cell frequencies were reliably detected by AIM and correlated between fresh and cryopreserved nasal samples. Downregulation of the CD3/TCR complex was observed in nasal samples. These findings establish a robust approach for nasal Trm profiling, demonstrating that cryopreservation preserves functional antigen-specific T cells. This work enables centralized, minimally invasive nasal T cell analysis for multicenter studies, including mucosal vaccination trials and controlled human infection models.

immunology↗

bioRxiv2026

Maternal vaccination timing shapes the composition and maturation of antibody clonotypes transferred to the newborn

Newborns rely on maternally transferred antibodies for immune protection, acquired across the placenta and through breast milk. Despite this importance, how closely the inherited antibody repertoire resembles the mothers has not been examined at the clonotypic level. We combined BCR-Seq with proteomic Ig-Seq to track SARS-CoV-2-specific antibody clonotypes across maternal blood, cord blood, and breast milk from six mRNA-immunized pregnant individuals. Vaccination earlier in gestation generated more diverse peak IgG repertoires but greater contraction before delivery, yielding fewer transferred clonotypes. Vaccination later in gestation produced more restricted peak repertoires, but more clonotypes persisted to delivery and transferred to cord. Infant cord was enriched for persistent, highly somatically mutated, and intraclonally diverse IgG clonotypes, consistent with preferential transfer of affinity-matured antibodies. In contrast, breast milk IgA repertoires were largely distinct from systemic repertoires and underwent substantial remodeling despite stable antigen titers. These findings define molecular determinants of passive immunity shaped by vaccination timing relevant to optimizing maternal immunization.

immunology↗

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↗

bioRxiv2019

The role of structural pleiotropy and regulatory evolution in the retention of heteromers of paralogs

Many paralogs derive from the duplication of genes encoding homomeric proteins. Such duplication events lead to the formation of homomers and heteromers, thus creating new structures from a single event. We exhaustively characterize this phenomenon using the budding yeast protein-protein interaction network. We observe that paralogs that heteromerize are very frequent and less functionally diverged than those that lost this property, raising the possibility that heteromerization prevents functional divergence. Using in silico evolution, we show that for homomers and heteromers that share binding interfaces, mutations on one complex have pleiotropic effects on the other complex, resulting in highly correlated responses to selection. As a result, heteromerization could be preserved indirectly due to selection for the maintenance of homomers. By integrating data on gene expression and protein localization, we find that regulatory evolution could play a role in overcoming these structural pleiotropic effects and in allowing paralog functional divergence.

evolutionary biology↗