Early development of encephalomyocarditis (EMC) virus-induced orchitis in Syrian hamsters.

Lesions associated with encephalomyocarditis (EMC) virus in the testes of Syrian hamsters were investigated. Histopathologic changes were first detectable by light microscopy at 3 days postinoculation (DPI). Immunohistochemically, virus antigens were detected in the cytoplasm of germ cells and Sertoli cells in some seminiferous tubules beginning at 2 DPI. The following ultrastructural changes were observed: 1) swelling of mitochondria and dilatation of endoplasmic reticulum in germ cells, 2) large number of residual bodies in seminiferous tubules, 3) aggregates of virus-like particles in the cytoplasm of degenerated cells and tubular lumen, 4) condensation of cytoplasm and dilatation of endoplasmic reticulum in Sertoli cells, and 5) degenerative changes in capillary endothelial cells.

Encephalomyocarditis (EMC) virus-induced testicular lesion in BALB/c mice.

Characteristics of encephalomyocarditis (EMC) virus-induced testicular lesions were investigated in 4- and 8-week-old BALB/c male mice after intraperitoneal (i.p.) and intratesticular (left) (i.t.) inoculation of the D variant of EMC virus (EMC-D). Apart from variation in severity and incidence, the histopathological nature of the resultant testicular lesion was similar in all infected mice, and was characterized by degeneration and necrosis of germinal cells and spermatogonia with inflammatory infiltration. Almost all the inoculated left testes of the i.t. group developed marked lesions. In general, the virus titre in the testis and incidence of testicular lesions were higher in 4-week-old mice than in 8-week-old mice. In addition, testicular lesions developed earlier and with a higher incidence in the PBS-inoculated right testis of the i.t. group than in either testis of the i.p. group of the same age.