Multiple target cells type for infection by RadLV(Rs), a radiation leukemia derived virus

In order to determine which cell type is susceptible to RadLV(Rs) infection, cell suspensions from different tissues were cultured in diffusion chambers (DC) in the presence of viral extracts and tested thereafter in vivo for a leukemogenic activity. Several experiments have clearly shown that neither passive entrapment of the virus nor spontaneous cell transformation occurred to a significant extent in the DC. This was demonstrated not only with RadLV(Rs) but also with Rauscher Leukemia virus (RLV), a much more potent oncogenic virus. Whereas spleen, bone marrow and thymus cell suspensions were susceptible to RadLV(Rs) infection in DC, only spleen and bone marrow could be infected by RLV. In the case of RadLV(Rs), cell suspensions devoid of T derived lymphocytes or deprived of surface immunoglobulins (Ig) remained able to propagate the disease. Moreover, the sera of the recipient mice injected with DC cultured cells contained increased concentrations of IgG₁, IgG_2a, IgG_2b, IgA and IgM. This denotes a polyclonal stimulation of B derived lymphocyes similar to that occurring after the in vivo administration of acellular extracts. The cells infected in DC with RadLV(Rs) were tumorigenic in the recipient mouse not by their own multiplication but by virus production. This was demonstrated by firstly, syncitia formation of XC cells by direct co-cultivation with DC cells; secondly, leukemia induction by cell free extracts prepared from the DC content; thirdly, absence of multiplication of DC infected cells from C57B1/Rb (6;15) 1 Ald mice (38 chromosomes) after injection in 40 chromosome recipients.