Molecular and In Silico Characterization of the Endogenous Jaagsiekte Sheep Retrovirus gag Gene Region from a Sheep in Türkiye

The Jaagsiekte sheep retrovirus is a betaretrovirus implicated in ovine pulmonary adenocarcinoma, with both exogenous and endogenous forms integrated into the sheep genome. In this study, we report the first molecular and in silico characterization of a 758 bp fragment of the endogenous Jaagsiekte sheep retrovirus gag gene isolated from a sheep sample in Türkiye (GenBank: MW145538). Sequence analysis revealed a continuous open reading frame encoding a 253 aminoacid gag protein with no premature stop codons, suggesting intact coding potential. Physicochemical analysis showed that the predicted protein is thermally stable, hydrophilic, and strongly basic, displaying characteristics typical of functional retroviral gag proteins. Conserved domain mapping confirmed the presence of canonical Matrix and Capsid motifs, indicating preservation of essential structural elements. GC content analysis revealed moderate nucleotide composition (42.08%), with localized fluctuations consistent with endogenous retroviral sequences. Phylogenetic reconstruction using the neighbor-joining method demonstrated that the Turkish enJSRV clusters within the enJSRV-B lineage, distinct from exogenous JSRV-I/II and other enJSRV subgroups. These findings suggest that the MW145538 sequence represents a conserved, potentially functional endogenous retroviral element, contributing to the growing understanding of enJSRV diversity and evolution in regional sheep populations.