Acute optic neuritis: a virological study in relation to multiple sclerosis.

Previous ultrastructural examination of peripheral blood lymphocytes revealed the presence of intranuclear filamentous structures in multiple sclerosis (MS) and in some optic neuritis (ON) patients. The present investigation was undertaken in the attempt to correlate the presence of such structures with the etiology of ON and MS and possibly to demonstrate the viral origin of the filaments. Suitable virological and serological techniques were used to detect and isolate infectious agents from peripheral blood samples and body excretions of 12 monosymptomatic ON patients at their first acute attack. Nevertheless, any efforts to demonstrate the presence of a virus in these patients have been unsuccessful: no evidence of active viral infection was obtained by serological studies of serum and cerebrospinal fluid samples, nor could viral antigens or inclusions be observed by immunofluorescence and cytochemical analysis. Negative results were also obtained from studies performed in parallel on MS patients and various controls. The significance of the failure to isolate infectious agents from either ON and MS patients is discussed.