PCR-based detection and partial characterization of a retrovirus associated with contagious intranasal tumors of sheep and goats.

A type D-related retrovirus has been demonstrated in enzootic nasal tumors (ENTs) of sheep and goats. This retrovirus, ENT virus (ENTV), has antigenic cross-reactivity with the jaagsiekte sheep retrovirus (JSRV), which is associated with a contagious lung tumor of sheep (sheep pulmonary adenomatosis). Here, we present the first report of nucleic acid sequence from ENTV which confirms, at the nucleic acid level, that this retrovirus is related to JSRV yet apparently distinct from it. Reverse transcription-PCR followed by restriction enzyme digestion specifically identified ENTV. By this technique, ENTV was demonstrated exclusively in tumor tissues and exudates of animals with ENT. Thus, there is a unique and consistent association between ENT and the retrovirus, just as there is between JSRV and sheep pulmonary adenomatosis. This gives further weight to the hypothesis that these retroviruses are the etiologic agents of the tumors.