JSRV env transcripts. (A) Northern
blotting of total RNA collected from 293T cells transfected with
pCMV2JS21, pCMV3JS21ΔGP, and mock-transfected 293T cells. Filters
were hybridized with the env-2 probe as described in Materials
and Methods. 293T cells transfected with pCMV3JS21ΔGP lack
the 7.5-kb band (corresponding to the full-length JSRV genome) because
the gag and pol sequences have been
deleted. (B) Northern blotting of total RNA from NIH 3T3
cells transformed by pCMV2JS21, parental NIH 3T3 cells, lung from a
healthy sheep, and lung from tumor lesions of two sheep affected by
OPC. Both the 7.5- and 2.4-kb transcripts are readily visible whereas
the 1.2-kb transcript is present at a low level.