EMC virus and cultured human fetal pancreatic cells. Ultrastructural observations.

Tissue cultures of pancreatic acinar cells of seven human fetuses were infected with either the M or the E variant of the encephalomyocarditis (EMC) virus. Between the third and fifth days after infection, severe ultrastructural damage was noted. Margination, condensation, and fragmentation of the nuclear chromatin and the appearance of numerous cytoplasmic vesicles filled with finely granular material were the major changes observed. Viral particles were not identified. One hundred plaque-forming units (PFU) were sufficient to induce these alterations with the M variant while 10,000 PFU were needed to obtain the same results with the EMC-E virus. The described lesions are qualitatively similar to those induced in vivo in experimental CD-1 mice infected with the virus.