Lack of association between polymorphic copies of endogenous Jaagsiekte sheep retrovirus (enJSRVs) and Ovine Pulmonary Adenocarcinoma

• The association between the presence of enJSRVs and OPA disease was studied.
• enJSRVs zygosity was assessed, being the youngest enJSRVs heterozygotes.
• The provirus enJSRV-16 has suffered a recent proliferation in Latxa sheep breed.
• Polymorphic enJSRVs do not appear to be associated with OPA development.

Ovine Pulmonary Adenocarcinoma (OPA) is a retrovirus-induced lung tumor of sheep, goat and mouflon, and its etiologic agent, Jaagsiekte sheep retrovirus (JSRV) is the only virus known to cause a naturally occurred lung adenocarcinoma. The oncogenic JSRV has several endogenous counterparts termed enJSRVs, some of which have been shown to interfere with JSRV replication at early and late stages of the retroviral cycle inhibiting JSRV exit from the cell, and thus, protecting sheep against the infection. In this work, Latxa sheep breed animals were classified depending on the presence/absence of OPA-characteristic clinical lesions in the lung. Using a PCR genotyping method and a logistic regression-based association study, five polymorphic enJSRV copies were analyzed in 49 OPA positive sheep and 124 control individuals. Our results showed that the frequency of the provirus enJSRV-16 is much higher in Latxa sheep breed than in other breeds, suggesting a recent proliferation of this provirus in the studied breed. However, no polymorphic enJSRV was found to be statistically associated with the susceptibility/resistance to OPA development.