Table 2.

Contribution of cp45 mutations to the ts  phenotype

ViruscVirus titera (log10 PFU/ml) at indicated temperature (°C)ts pheno-typeb
cp458. 5.1 2.3<0.7+
r cp458. 5.1 2.1<0.7+
r cp45 3′NCMFHN7.05.8 3.2 3.01.6<0.7<0.7+
r cp45 3′NL7.35.9 3.2 2.0<0.7<0.7<0.7+
r cp45 L7.26.95.4 2.9 <0.7+
r cp45 3′N7. 4.3 <0.7+
r cp45 M7. 5.3 <0.7
r cp45 C6. 3.9
r cp45 F7.
r cp45 HN6.
rPIV3 wt7.
  • a Plaques were enumerated by immunoperoxidase staining after incubation for 6 days at the indicated temperature. Values are the means of two to four experiments. Underlined values represent the lowest nonpermissive temperature at which a 100-fold reduction of plaquing efficiency occurs compared to plaquing efficiency at 32°C, and this is defined as the shutoff temperature of plaque formation.

  • b A virus is defined as bearing (+) the ts phenotype if its reduction of plaque formation at 40°C is ≥100-fold the reduction of rPIV3 wt at 40°C.

  • c cp45 is biologically derived, and the other viruses are recombinants.