Figure 1.

Comparison of the replication of HPIV1 wt and rHPIV1 mutant viruses containing the indicated mutations in the P/C, HN and L genes in a multiple cycle growth curve. Monolayer cultures of LLC-MK2 cells and Vero cells were infected at a multiplicity of infection of 0.01 TCID₅₀/cell and incubated at 32°C. The medium was removed on days 0 (residual inoculum), 2 and 4–11 post-infection, frozen for later determination of virus titers, and replaced by fresh medium containing trypsin. The virus titers shown are the means of 3 replicate cultures.