Experimental Sendai virus-induced labyrinthitis in guinea pigs. An ultrastructural study of cochlear lesions.

Guinea pigs were inoculated with a Sendai virus into the scala tympani and subsequent pathological changes of the cochleas were investigated by electron microscopy. Replication of the virus was indicated by buddings at the endolymphatic surface and by the intracytoplasmic occurrence of filamentous substances, ie, nucleocapsids. Budding viruses or free virus particles observed in a series of our experiments were identified as Sendai viruses by means of the immunological labeling with ferritin. Viral lesions, which were defined as the pathological changes of the cells associated with virus multiplication, were found in eight cochleas out of 20. This study revealed that the early lesions of the cochleas infected by Sendai viruses were primarily confined to Reissner's membrane and the stria vascularis, but the sensory cells were not affected.