Figure 5.
Vaccinia virus (VACV) lacking N1 or expressing N1.I6E induce better protection to virus challenge. (a) Groups of five mice were infected intradermally with the indicated viruses. At 28 days post-infection mice were challenged intranasally with VACV (5 × 106 plaque-forming units of VACV WR) and weight change was monitored. Each mouse was compared to its original weight on day zero and data are expressed as the percentage ± SEM. (b) Groups of five mice were infected and challenged as (a), killed on day 1 or day 4 post-challenge (p.c.) and virus titres in the lungs were measured by plaque assay. Data are mean titre ± SEM, **P < 0·01. (c) Sera from mice infected as in (a) were collected 28 days post-infection and assayed for neutralization of VACV strain WR. The median value for each population is represented by a horizontal black bar. Significant differences between groups are shown, Mann–Whitney U-test. *P < 0·05, n = 15.