FIG. 7.

Allostimulation results in copackaging of ecotropic and xenotropic MuLV RNAs. Multiparous BALB/cJ females that had been mated to B6 males were injected with either B6 lymphocytes (mice of groups A to C, where each group consists of five mice) or with PBS (mice of group D, five mice per group). Six months later, mice were sacrificed and their spleens were divided into three parts; one part was used to isolate RNA, which was subjected to Northern blot analysis, and cells isolated from the two residual parts were cocultured with SC-1 and mink lung cells. RNA was isolated from these SC-1 and mink lung cells and was subjected to Northern blot analysis. Harvests (100 μl) from infected mink lung cells (virus C) after a sixth passage were used to infect BALB 3T3 and NIH 3T3 cells. RNA isolated from these infected cells after a third passage was also subjected to Northern blot analysis with the indicated probes.