Table 3.

Contribution of cp45 mutations to the ca  phenotype

VirusdVirus titer (log10PFU/ml)a at 20°CIncrease (log10) in titerbca phenotypec
r cp456.54.1+
r cp45 3′NL4.82.4+
r cp45 3′N4.11.7+
r cp45 3′NCMFHN3.51.1+
r cp45 L2.60.2
r cp45 C2.50.1
r cp45 F2.50.1
r cp45 HN1.9−0.5
r cp45 M1.6−0.8
PIV3 wt2.4
  • a L-132-cp2-7 cells were infected with each of the indicated viruses, and after incubation at 20 and 32°C virus was harvested and titers were determined. The virus titer at 32°C was at least 7.6 log10 PFU/ml for each of the viruses.

  • b Compared to the titer of PIV3 wt at 20°C.

  • c The presence (+) of the ca phenotype is defined as a 10-fold increase in replication at 20°C compared to that of PIV3 wt at 20°C.

  • d PIV3 wt and cp45 are biologically derived viruses, and the others are recombinant viruses.