Kumpanenko, Y. | Search bioRxiv

bioRxiv2025

Sex determination of Syrian hamster pups using placental tissues

Molecular sex determination in Syrian hamsters (Mesocricetus auratus) has been limited by incomplete annotation of Y-linked loci in currently available genome assemblies. Here, we evaluate the Y-linked gene PRSSLY, which encodes a testis-specific serine protease-like protein, as a molecular marker for genetic sexing of Syrian hamster embryonic and placental tissues. Primers flanking a conserved PRSSLY coding region produced a male-specific amplicon showing 100% concordance with results from the established KDM5C/KDM5D PCR assay in E15.5 tail biopsies. SYBR Green-based qPCR enables the accurate detection of PRSSLY, characterized by a unique melt-curve profile, exclusively in male samples, allowing for efficient and sensitive mid-throughput analysis. Among 417 placental samples from 39 dams tested, which naturally contain a mixture of maternal and embryonic genomes, the sex of individual pups was classified with 85% specificity, with the remaining ambiguous samples confirmed as male by PCR and agarose gel electrophoresis. This assay provides a robust and reproducible approach for accurate sex genotyping in developmental and reproductive studies using Syrian hamsters.

genetics↗

bioRxiv2024

Antigenic imprinting dominates humoral responses to new variants of SARS-CoV-2 in a hamster model of COVID-19

The emergence of SARS-CoV-2 variants escaping immunity challenges the efficacy of current vaccines. Here, we investigated humoral recall responses and vaccine-mediated protection in Syrian hamsters immunized with the third-generation Comirnaty(R) Omicron XBB.1.5-adapted COVID-19 mRNA vaccine, followed by infection with either antigenically closely (EG.5.1) or distantly related (JN.1) Omicron subvariants. Vaccination with YF17D vector encoding a modified Gamma spike (YF-S0*) served as a control for pre-Omicron SARS-CoV-2 immunity. Our results show that both Comirnaty(R) XBB.1.5 and YF-S0* induce robust, however, poorly cross-reactive, neutralizing antibody (nAb) responses. In either case, total antibody and nAb levels increased following infection. Intriguingly, the specificity of these boosted nAbs did not match the respective challenge virus but was skewed towards the primary antigen used for immunization, suggesting a marked impact of antigenic imprinting; confirmed by antigenic cartography. Furthermore, limited cross-reactivity and rapid decline of nAbs induced by Comirnaty(R) XBB.1.5 with EG.5.1 and, more concerning, JN.1. raises doubts about sustained vaccine efficacy against recent circulating Omicron subvariants. Future vaccine design may have to address two major issues: (i) to overcome original antigenic sin that limits the breadth of a protective response towards emerging variants, and (ii) to achieve sustained immunity that lasts for at least one season.

immunology↗