Studies on infectious mononucleosis: a progress report.

The authors recently reported the occurrence of an unstable cytopathic effect and a "first passage" interference phenomenon in tissue culture as well as the detection of antigens by immunofluorescence following inoculation of material from patients with infectious mononucleosis.These tissue cultures have since been discovered to be contaminated by a bacterial L-form. The part played by the contaminant in the results obtained has been determined: it can explain only one of the patterns shown by immunofluorescence.The same labile interference phenomenon has been observed by two independent investigators.