Functional analysis of the UL24 protein of suid herpesvirus 1.

The UL24 homologous genes are conserved in alphaherpesviruses. However, the proximity of the UL24 gene and the UL23 gene encoding for thymidine kinase (TK) in the genome of suid herpesvirus 1 (SuHV-1) makes it difficult to mutate UL24 without affecting the expression of the TK gene, and thus functional studies of the UL24 gene have lagged behind. In this study, CRISPR/Cas9 and homologous recombination were adopted to generate UL24 and TK mutant viruses. Deletion of either the UL24 or the TK gene resulted in significantly reduced SuHV-1 replication and spread capacity in Vero cells. However, UL24-deleted virus still maintained a certain degree of lethality in mice, while TK-deleted viruses completely lost their lethality in mice. Similarly, neurovirulence of UL24-deleted virus in mice was not significantly affected compared to parental virus. In comparison, infection with the TK-deleted viruses resulted in significantly reduced neurovirulence and complete loss of lethality. In addition, and for the first time, viral UL24 protein was found to be expressed late during SuHV-1 infection; enhanced green fluorescence protein (eGFP) labeled UL24 protein was shown to be localized in the nucleus via heterologous expression. In conclusion, the UL24 gene of SuHV-1 encodes a nuclear-localized viral protein and acts as a minor virulence-associated factor compared to the TK gene.

[A case with trigeminal herpes zoster manifesting a long lesion of the spinal trigeminal nucleus and tract on MR T2-weighted image].

We reported a 53-year-old man with the right trigeminal herpes zoster with preceding neuralgia (preherpetic neuralgia) in the right upper cervical nerve area. He developed dysesthesia and scapular pain in the right second cervical nerve area. 5 days later, herpes zoster emerged in the area of the right maxillary division of trigeminal nerve. Furthermore, he developed paralysis on the right facial muscle on the 12th day after the onset of scapular pain. Neurological examination revealed decrease in superficial sensation accompanied by pain and dysesthesia in the areas innervated by the right maxillary division of trigeminal nerve and the right second cervical nerve, and the right peripheral facial nerve palsy. Any rash was not observed in the right second cervical nerve area throughout the course. The cerebrospinal fluid showed a mild mononuclear pleocytosis. The antibody titer for varicella zoster virus (VZV) was elevated in both cerebrospinal fluid and blood serum. T2-weighted magnetic resonance (MR) image revealed a continuously long high-signal lesion corresponding to the right spinal trigeminal nucleus and tract, extending from the lower pons to the second cervical segment of the spinal cord. This lesion could have resulted from a centripetal migration of VZV from the Gasser ganglion to the spinal trigeminal nucleus and tract, which was probably related to the preherpetic neuralgia in the upper cervical nerve area without rash.

Study of transneuronal passage of pseudorabies virus in rat central nervous system by use of immunohistochemistry and in situ hybridization.

We studied the uptake and sequential transneuronal passage of pseudorabies virus (PRV) in rat CNS by use of a combination of immunohistochemistry and in situ hybridization. Protocols for rapid detection of PRV by immunohistochemistry and in situ hybridization in rats with PRV infection of the CNS after intranasal instillation of a wild-type strain of PRV were optimized in vitro, using porcine kidney-15 cells. Pseudorabies virus-specific hybridization signals appeared in the cytoplasm and nucleus of PRV-infected porcine kidney-15 cells by postinoculation (PI) hour 6. In tissue sections of PRV-infected rats, PRV nucleic acids were detected in areas of the rat brain in close proximity to the areas in which PRV antigens were evident. The PRV was initially found in the nucleus of trigeminal ganglion neurons at PI hour 24. At PI hour 72, PRV antigens were observed in the mid-brain, and 24 hours later, in the telencephalon. We also found evidence of specific progressive transsynaptic transmission of the virus, and, on the basis of that, we have constructed a map of the synaptic contacts and pathways in the brain. Therefore, combined use of immunohistochemistry and in situ hybridization was useful for characterizing the pathogenesis of PRV in the CNS of rats after intranasal inoculation, following a pattern that mimics PRV infection of the natural host.