Pathogenesis of a Model Gammaherpesvirus in a Natural Host

Murine gammaherpesvirus 68 (MHV-68) infection of laboratory mice (Mus musculus) is an established model of gammaherpesvirus pathogenesis. The fact that M. musculus is not a host in the wild prompted us to reassess MHV-68 infection in wood mice (Apodemus sylvaticus), a natural host. Here, we report significant differences in MHV-68 infection in the two species: (i) following intranasal inoculation, MHV-68 replicated in the lungs of wood mice to levels approximately 3 log units lower than in BALB/c mice; (ii) in BALB/c mice, virus replication in alveolar epithelial cells was accompanied by a diffuse, T-cell-dominated interstitial pneumonitis, whereas in wood mice it was restricted to focal granulomatous infiltrations; (iii) within wood mice, latently infected lymphocytes were abundant in inducible bronchus-associated lymphoid tissue that was not apparent in BALB/c mice; (iv) splenic latency was established in both species, but well-delineated secondary follicles with germinal centers were present in wood mice, while only poorly delineated follicles were seen in BALB/c mice; and, perhaps as a consequence, (v) production of neutralizing antibody was significantly higher in wood mice. These differences highlight the value of this animal model in the study of MHV-68 pathogenesis.