FIG. 2.

Scheme for construction of fMHV by targeted recombination between the MHV N gene deletion mutant, Alb4 (27), and donor RNA transcribed from the plasmid pFM1. The deletion in the Alb4 N gene is shown as a discontinuity. A single crossover event anywhere within the HE gene fragment of the donor RNA should generate a recombinant, fMHV, containing both the ectodomain-encoding region of the FIPV S gene (shaded) and the wild-type MHV N gene. The recombinant should simultaneously lose the ability to infect murine cells and gain the ability to infect feline cells.