FIG 4.

Sequence changes at position 4922 can compensate for a defect in Sla5045. (A) Schematic illustration of the region of the MNV genome mutated in m53 and m53SupA. The sequence of the region shown is represented in the positive polarity to highlight the NS7 reading frame, with the negative-polarity sequence shown below. The amino acids encoded by the region are highlighted, as well as the position of the SupA mutation (in italics) and the mutations introduced in m53. (B) Virus yield following reverse genetics rescue of cDNA constructs containing wild-type (WT) or m53 MNV cDNA with various changes at position 4922. Note that the nucleotide sequences shown represent the sequence of the antisense RNA genome, with G representing the previously isolated SupA suppressor mutation and A representing the nucleotide present in the wild-type cDNA construct. Reverse genetics recovery was performed as described in Materials and Methods and then the virus yield at 24 h posttransfection determined by TCID50. The dotted line represents the detection limit of the assay, with error bars representing the SEM.