Abstract
Primary cell cultures and a line consisting of fibroblast-type cells were obtained from tadpoles of the common frog, Rana temporaria. One cell line was taken through 21 subcultures during 5 months, when it was abandoned due to contamination by an anonymous Mycobacterium which was completely resistant to antibiotics. Cells from the primary cultures supported the growth of three tick-borne arboviruses without any cytopathic effect; Quaranfil, louping ill (two strains), and Langat. One of the virus strains, louping ill 369T2, was serially passaged in the cell cultures 11 times in 11 weeks, during which time there was considerable multiplication of virus.