Induction of Transformed Phenotypes in Sheep Fibroblasts by Culture Fluids from Cells Persistently Infected with Bovine Leukemia Virus

Abstract

FLK cells are fetal lamb kidney cells persistently infected with bovine leukemia virus (BLV). 3178 cells, originating from calf-form bovine lymphosarcoma, also showed persistent production of BLV and alteration of cell morphology after treatment with 5'-iodo-2'-deoxyuridine. In the present paper, the first in vitro transformation of sheep fibroblasts by inoculation with BLV materials from these two cell lines is described. In a few passages after inoculation with these viral materials, morphological alteration occurred. The morphologically altered cells were grown as stable cultures and showed such transformed phenotypes as growth in soft agar medium, increased uptake of 2-deoxy-o-glucose and tumorigenicity in athymic nude mice. This result, together with our previous observation of simultaneous induction of BLV expression and morphological alteration in 3178 cells, suggests the presence of some transforming capacity in these BLV materials similar to that in, for example, murine or avian acute leukemia viruses. The possible acquisition of such capacity during the prolonged passage is discussed.

Monoclonal antibodies against BLV-transformed sheep cells

“…Bovine leukemia virus (BLV) is a unique retrovirus which causes naturally occurring lymphosarcom~ in cattle. Although BLV is competent for replication, it is able to transform sheep fibrobtasts in vitro (5,6). Previous analysis by using polyclonM antibody, showed that the transformed sheep fibroblasts (SF-28 cells) expressed new antigen(s) which differed from BLV structural proteins (gp51 and p24) and might be associated to transformation (5).…”

Neoplastic transformation of fetal lamb kidney cells by bovine leukemia virus

“…However, little or no successful in vitro transformation of sheep and calf cells by BLV has been reported. Onuma et al (1981) reported the induction of transformed phenotypes in sheep fibroblasts from testes following inoculation with BLV, but cells infected with BLV became transformed only after several passages. We describe herein the rapid successful transformation of fetal lamb kidney (FLK) cells by BLV.…”

Structure of a Defective Provirus of Bovine Leukemia Virus

“…Thus, the mechanism of the cellular transformation by BLV still remains enigmatic. However, the presence of a BLV provirus in all the leukemic cells (1) and the ability of BLV to transform cells in vitro (9,10) suggest that the BLV genome possesses a possible transforming gene. Recent molecular biological (16) and biochemical (14) studies suggest that the BLV genome harbors the .unique XBL gene encoding a non-structural 38 kDa protein, corresponding to the X gene of HTLV (16,17).…”