Production of Friend Leukemia Virus in a Mouse Lung Cell Line

Abstract

SUMMARY : 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.

Ultraviolet inactivation of murine leukemia virus and its assay in permissive and non‐permissive cells

“…Friend leukemia virus (FLV) preparation was the culture fluid of MLg42FV131 cell line (Yoshikura et al, 1967) or 10% homogenate of FLV-infected DDD mouse spleens; the latter was obtained from Dr. T. Odaka of this department. Murine sarcoma-leukemia virus complex (MSV-MLV) was a Moloney isolate which was propagated in NIH3T3 or YH-7 cells.…”

Hematopoietic CFU in mice infected by the polycythemia‐inducing friend virus. I. number of CFU, and differentiation pattern in the spleen colonies

“…The polycythemia-inducing Friend virus (FVP) was obtained from Dr. Yoshikura (1967). A 10% cell-free extract prepared from infected C3H-He mouse spleens and stored in liquid nitrogen was employed for all the experiments.…”

“…Spleens to be examined for histological identification of the colonies were fixed in buffered formalin with added saccharose (Zajdela, 1962). Each spleen was embedded in paraffin and sectioned longitudi- The colonies per spleen section were counted and typed under the microscope according to cytological criteria described previously (Curry and Trentin, 1967) care being taken not to count the same colony twice in different sections.…”

“…The recipients' spleens were removed 9 days later, fixed in Bouin's solution, and the macroscopic colonies were counted. Spleens to be examined for histological identification of the colonies were fixed in buffered formalin with added saccharose (Zajdela, 1962). Each spleen was embedded in paraffin and sectioned longitudi-…”

In vitro infection of lymphoid cells by thymotropic radiation leukemia virus grown in vitro.

“…Long-term passage of MuLV through mouse embryo fibroblasts usually results in the production of "attenuated" virus that has lost most or all of its pathogenic properties; this has been shown to be true for the Friend (8)(9)(10) and Rauscher (10)(11)(12) cently also for the natural lymphatic leukemia-inducing Gross-AKR (10,13,14) and the radiation leukemia (RadLV) (15) variants of MuLV. In contrast to the loss of oncogenicity of MEF-grown virus, long-term in vitro culture of MuLV has consistently produced potent in vivo leukemogenic viruses whenever the virus was cultered in or produced by cells of lymphatic origin (7,16,17).…”