Endogenous JSRV-like proviruses in domestic cattle: Analysis of sequences and transcripts

Jaagsiekte retrovirus is an exogenous (exJSRV) beta-retrovirus with a simple genome. It causes lower airway epithelial cell tumors in small ruminants. Endogenous (enJSRV) counterparts of exJSRV are present in different copy numbers in numerous Bovidae family members.This work has focused on enJSRV in Simmental (Germany) and Limousine (France) beef breeds of domestic cattle and domestic goat. Of the enJSRV sequences in cattle, the orf-x sequences were about 99% identical, the LTR sequences were about 97% identical and the env sequences were nearly 95% identical to the corresponding endogenous sequences in sheep. A significant polymorphism of the proviral sequences between the cattle breeds was noted. Clonal analyses of the amplicons suggest two enJSRV proviruses in cattle genome. The endogenous sequences revealed in goat were closer to enzootic nasal tumor virus (ENTV) from goat rather than to enJSRV from sheep.The expression of enJSRV in cattle was partial (env only) and detected exclusively in bone marrow.