FIG. 3.

In vitro infection of ovine cell lines. Four different ovine cell lines were infected with JSRV₂₁ (I) or in parallel with heat-inactivated virus (H), and the cultures were serially passaged. PCR for exogenous JSRV with primers from the U3 region of the LTR was carried out on 500 ng of infected-cell DNA. The diagnostic 176-bp product is indicated by an arrow. PCR assays were carried out on CP cells at passage 7 after infection and on the other three cell lines at passage 5.