Fig 9. Immunization with the PRV pUL37 R2 mutant protects against lethal encephalitic infection.

Mice were vaccinated intranasally with 5 μl of the PRV R2 mutant (6.4 x 10⁸ PFU/ml). Subsequent wild-type challenge was performed by intranasal inoculation with 5 μl of wild-type PRV (8.8 x 10⁹ PFU/ml) at the indicated day post vaccination. Mice showing no signs of disease were euthanized at 672 hours (28 days) post challenge and are indicated in red. * Mouse was euthanized at 504 hours post challenge due to presentation of tremors and an unusual head lesion, although subsequent histology found no indication of viral encephalitis. ** Mouse was euthanized at 168 hours post challenge due to weight loss.