Gene expression changes in the turkey hen vagina in response to artificial insemination across the lying cycle

Background : The vagina is the main site for sperm selection in turkey hens. However, the specific genes and pathways altered in response to sperm and laying cycle have not been fully investigated. The objective of this study was to determine the changes in gene expression of the vagina in response to artificial insemination through the laying cycle of turkey breeder hens. Vaginal tissues were collected from hens artificially inseminated (semen group), inseminated with extender (sham group), or not inseminated (virgin group) (n=5/group). Additional tissues were collected from semen and sham groups at peak lay, and end of lay. Total RNA was extracted for sequencing. Differentially expressed genes were identified among groups, and functional annotation was performed. Results : Differences in gene expression were observed in comparisons based on lay cycle and insemination treatment. During early lay, extender alone led to increased expression of antimicrobial genes, cell proliferation, differentiation, and remodeling compared with virgin. By contrast, semen treatment predicted the activation of innate immune cell pathways. At peak lay, a higher expression of histone deacetylase 7-like mRNA was observed in response to semen compared with sham, along with a predicted inhibition of immune Calcineurin-NFAT Signaling Pathway . Semen treatment led to a higher expression of sperm binding proteins including deleted in malignant brain tumors 1 protein-like and Zona Pellucida 1 at peak lay when compared with early lay. Finally, semen treatment resulted in increased expression of Urotensin 2B and decreased expression of antimicrobial genes including β-defensin 2, catheldicins 2 and 3, sialoadhesin, attractin-like 1, lysosomal-associated membrane protein 3, leukocyte cell-derived chemotaxin-2, and hepatocyte growth factor at the end of lay compared with sham. Conclusions : Results from this study indicate that the turkey vagina actively responds to extender and sperm and that this response changes across the laying cycle. Gene expression changes indicate a shift in the innate and adaptive immune response of the vagina during the laying cycle that can be dependent or independent of sperm. The presence of sperm binding proteins in the vagina with highest expression at peak lay, coincides with peak fertility and could serve as potential markers of fertility.