FIG 10.
Testing of Δ25galK and Δ56-57 deletion recombinants as attenuated recombinant vaccine candidates. The virulence of the recombinant viruses indicated was first tested in carp (first line of graph: four replicates per condition; n = 20 fish; average weight, 2.42 ± 0.95 g; average age, 6 months old). On day 0, fish were mock infected or infected for 2 h by immersion in water containing 40 (dotted line) or 400 (continuous line) PFU of virus/ml. The survival rate was measured over a period of 42 days. The immune protection conferred by primary infection was then tested for Δ25galK and Δ56-57-infected fish at 42 dpi by distributing mock-infected fish and fish that survived the primary infection into duplicate tanks (n = 20) and challenging them by cohabitation with fish infected with the M3 strain (middle line of graphs) or the FL strain of CyHV-3 (lower line of graphs). The survival rate was measured according to time postchallenge.