Fig. 1.

Protection against MuHV-4 replication by immune sera. (a) C57BL/6 mice were given 3×10⁴ p.f.u. MuHV-4 intranasally (i.n.) and at the same time treated or not with 200 μl immune serum intraperitoneally (i.p.). Infectious virus in lungs was measured by plaque assay 3 days later. Each point shows the titre for one mouse; × shows mean values. Immune serum reduced lung titres significantly (P<0.0005 by two-tailed Student's t-test). (b) C57BL/6 mice were infected and treated or not with immune serum as in (a). The effects of immune serum on day 3 and day 6 titres were then compared. The reduction in titre was significant at day 6 (P<0.0001), but not at day 3 (P=0.06). (c) BALB/c mice were infected and given immune serum as in (a), or naive serum as an additional control. Virus titres in lungs were determined after 5 days. Immune serum reduced titres significantly compared with either virus only or naive serum (P<0.01). Naive serum had no effect compared with virus only (P=0.5).