PRODUCTION OF FRIEND LEUKEMIA VIRUS IN A MOUSE LUNG CELL LINE

Abstract

Three cell lines persistently infected with Friend leukemia virus were obtained by treating MLg cells with a homogenate of Friend leukemia virusinfected mouse spleens. Two of them were highly leukemogenic and the other was low leukemogenic. The virus titer of the culture fluid of the highly leukemogenic cell lines was about 10³ ID₅₀/0.2 ml or more and the undiluted culture fluid induced leukemia in young adult mice within one or two weeks. Virus particles in the low leukemogenic cell line revealed by electronmicroscopy were morphologically indistinguishable from and not fewer than those found in one of the former two cell lines. The persistently infected cell lines could be stored at -70 C without impairing the virus production from the cells.