Electron microscopic studies of viral agents in Crohn's disease.

Viral agents isolated from ileal filtrates of patients with Crohn's disease have been successfully cultivated in continuous rabbit ileum tissue-culture and grown to titres sufficient to allow electron microscopic characterisation. Electron microscopic studies showed clusters of viral particles only in tissue-cultures inoculated with cultivated viruses originally obtained from tissues from patients with Crohn's disease. Control cultures showed no evidence of viral agents. The mean virus-particle diameter was 30 nm. An electron-dense central core was present and a spiculated coat was demonstrated. The physical chemical properties of this agent, as previously described, together with the electron microscopic appearance are consistent with the appearance of a picornavirus.