Fig. 7.

Low dose in vivo infection with gL⁻ and gp70⁻ viruses. (a) The gL⁻gp70⁻.2 mutant was compared with wt MuHV-4 by intranasal inoculation of mice with 1–1000 p.f.u. Twelve mice per group for each dose were scored as infected or not at 16 days p.i. by infectious centre assay of spleens and by ELISA for virus-specific serum IgG, with concordant results. The gL⁻gp70⁻ infection rate was significantly lower than wt at 1–10 p.f.u. (P<0.005 by Fisher's exact test), but not at 100 p.f.u. (P=0.1). (b) Virus knockouts were compared with wt for infectivity (12 mice per group) after intranasal inoculation. The gL⁻REV and gL⁻gp70⁻gp150⁻ mutants were derived from the gL⁻gp70⁻ mutant. Their infectivities were equivalent to wt. The gL⁻ and gL⁻gp70⁻ infection rates were both significantly less than wt at 1 p.f.u. (P<0.05 by Fisher's exact test). Only the gL⁻gp70⁻ infection rate was significantly lower at 10 p.f.u. (P<0.02). At 1 p.f.u. the gL⁻gp70⁻ infection rate was significantly lower than that of the gL⁻ (P<0.01).