Fig. 4
The UL7-MU viral strain exhibits lower virulence in infected mice compared with the WT strain. a BALB/c mice were infected via intranasal instillation of 2.3 × 105 PFU of WT HSV-1 (open boxes), UL7-MU (filled circles), MU-complemented P1 (filled triangles) or PBS (open rhombuses) as a control. The weights of the mice were measured every 2 days. Data are shown as means ± SD. ∗ P < 0.05; ∗∗∗ P < 0.005. b The survival rates of mice infected with WT HSV-1 (open boxes), UL7-MU (filled circles), MU-complemented P1 (filled triangles) or PBS (open rhombuses). c Pathological changes in the CNS tissues and spinal cords of mice infected with WT, UL7-MU, MU-complemented P1 or PBS. Tissue sections were stained with H&E and imaged using an optical microscope at 200× magnification. Tissue hyperemia is highlighted with red arrows; infiltration of inflammatory cells is highlighted with black arrows. d HSV-1 immunohistochemistry of CNS tissues and spinal cords in WT, UL7-MU, MU-complemented P1 or PBS-infected mice. Non-specific staining was observed in PBS-infected mice. Positive expression of the HSV 1 antigen was detected in WT, UL7-MU and MU-complemented P1 infected mouse CNS tissues and spinal cords (arrows). e Viral load detection in the CNS of mice challenged with WT (open boxes), UL7-MU (filled circles) or MU-complemented P1 (filled triangles) viruses, as determined by real-time RT-PCR. Viral copy numbers were quantified according to an HSV-1 DNA standard. Data are shown as the means ± SD (three independent mice). ∗ P < 0.05; ∗∗ P < 0.01