FIG. 1.

Strategy for mapping the responsible mutation in ts138. Infectious cDNA clones that contained parts of each mutant nsP coding region in place of the corresponding regions of parental pToto1101 cDNA were made as described in Materials and Methods. Unique restriction endonucleases and their cleavage sites are marked under the schematic of the viral nsP1 to nsP4 regions. The solid regions represent sequences from the mutant; the open regions are those from pToto1101.