Persistent infection and transformation of mouse glial cultures by K virus, a murine papovavirus

Summary Foetal mouse glial cultures were inoculated with murine K papovavirus and subjected to serial subcultivation. Two cell lines were developed. The first of these, KVBCG2A, remained positive for viral infectivity and K virus capsid (V) antigen for over 30 subcultivations. Productive infection was not abolished by serial subcultivation in the presence of antiviral antibody. The second cell line, KVBCG1B, became negative for infectious virus and K virus V antigen, could be cloned from single cells and produced tumours in mice. Sera from tumour-bearing animals produced nuclear fluorescence of KVBCG1B cells and K virus-infected mouse embryo cells but did not react with uninfected mouse embryo cells or with cells infected by polyoma virus. DNA hybridization studies confirmed the presence of K virus DNA in KVBCG1B cells and suggested integration of the viral genome into host chromosomal DNA. K virus produces both persistent infection and cell transformation in glial cultures derived from its natural host.