Characterization of clones derived from an attenuated strain of Rauscher murine leukaemia virus.

With a view to defining its subpopulations, an attenuated strain of Rauscher leukaemia virus, which comprises a majority of fragile virions, was closed by end-point dilution. The presence in the obtained clones of markers (analyzed by radioimmunoassay and isoelectric focusing) associated with Rauscher virus, together with persistent infectivity and leukaemogenicity, excluded the hypothesis that endogenous virus might have replaced the original Rauscher population. Due to the closing method employed, non fragile virions were obtained. Moreover, despite its selectivity for the lymphatic leukaemia virus component, sporadic cases of atypical erythroblastogenic leukaemia were observed.