Evidence for the presence of virus in clonal insulin-producing RINm5F cells.

The ultrastructural morphology of the clonal insulin-producing cell line, RINm5F, was investigated. Virus-like particles, probably C type viruses, were identified both intra- and extracellularly. Because these particles could not be found in the original transplantable tumor, it is probable that viruses were induced at some later stage in the development of the RINm5F cell line. All investigators using the RINm5F cells should be aware of the fact that these cells may contain one or several types of viruses, and of the possibility that these particles may interfere with a variety of cellular functions.