Studies on the experimental infection with herpesvirus

Subcutaneous infection of gingiva and its characteristics

Abstract

Pathogenesis of a virulent Miyama GC⁺ strain of herpes simplex virus type-1 (HSV -GC⁺) was studied in various routes of inoculation in a mouse model system. When Balb/c mice were inoculated intraperitoneally with 1.5×10⁵ plaque-forming units (PFU) of HSV-GC⁺, 100% of the mice died within 6-9 days. HSV-GC⁺ was recovered from organs such as the cerebrum, brain stem, and spleen after 2-5 days of inoculation, but not from the trigeminal ganglia, thymus and sera. Intracranial inoculation of 10 PFU HSV-GC⁺ also killed all of the mice. If mice, however, were inoculated subcutaneously in maxillary gingiva with 1.0×10⁷ PFU of HSV-GC⁺, they all survived. HSV-GC⁺ was recovered from the trigeminal ganglia and brain stem at the stage of an acute infection, but not from other organs tested. Other strains of HSV-1 such as HSV-GC- and HSV-F were also shown to be nonlethal when inoculated subcutaneously in maxillary gingiva. In an immunofluorescence test, it was revealed that there was twice as many TcRyγδ cells as noninfected mice detected in sections of maxillary gingiva when mice were infected subcutaneously in maxillary gingiva with HSV-GC⁺.
These data show that the virulence of HSV in mice was clearly dependent on the routes of inoculation, suggesting that there is a possibility of the existence of an oral defence mechanism, which may be different from that in peritoneal cavity.