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Twenty-four cell lines were established from uterine-oviductal flush fluid (UOFF) cells from 20 bovine leukosis virus (BLV)-infected embryo-donor cows and 4 BLV-free control cows harvested by the Ficoll-gradient technique. Similar epithelial-like and fibroblast-like cells were observed in the primary cultures of UOFF from both groups. BLV-antigens were not detected with direct immunofluorescence test in any of the cell-lines from the 20 positive BLV-cows but a positive reaction was observed with the competitive radioimmunoassay in one cell line only. Bovine syncytial virus (BSV) was detected (multinucleated cells) in five of the 20 cows, bovine virus diarrhea (BVD) in six and infectious bovine rhino-tracheitis (IBR) in one (by D-IF). Some of the cell lines had antigens to one (3/20) two (2/20) or three (1/20) different viruses as demonstrated by D-IF. There were no antigens to BLV, BSV or IBRV demonstrated in the BLV-free cows by both immunofluorescence test and radioimmunoassay. Permissiveness to the growth of BLV in the cell lines of bovine utero-tubal (BUT) origin was demonstrated by inoculating three of the 20 cell lines from BLV-infected cows and three cell lines from the 4 BLV-free cow by BLV suspensions. All six cell lines permitted the growth of BLV as shown by syncytia, and positive reactions with the immunofluorescence test but only three out of six lines were BLV-positive by radioimmunoassay.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood leucocytes, sediments of uterine flush fluid (UFF), eggs and embryos from 25 BLV-positive donor cows were tested for bovine leukemia (BLV) and bovine syncytial (BSV) viruses by cocultivation with fetal lamb spleen cells and by applying syncytium induction and immunofluorescence tests. BLV was diagnosed in 11/15 (73.3%) leucocyte and 4/25 (16.0%) UFF-sediment specimens as compared to BSV in 14/15 (93.3%) and 21/25 (84.0%) of the similar specimens and neither BLV or BSV were found in 26 eggs and 60 embryos collected from 20 of the 25 cows. Detection of BLV antigens by immunofluorescence was hampered by the competitive replication of both BLV and BSV and competitive growth in indicator cells and uterine cells. As BLV has not been observed in cells of UFF sediments, it was probably isolated from leucocytes present in the lumen of uterus or from blood seeping out from inapparent vessel damage during flushing. Isolation of BLV in UFF sediments gives additional evidence to the concept of a transplacental transmission by a not yet elucidated mechanism. The high rate of BSV recovery from cells of UFF sediments indicated that this virus is more wide-spread than previously shown and that it may play a role in causing disorders of the reproductive tract.