Increase of Antigen Production in BLV‐infected Cell Lines via Additional Expression of Tax

Abstract

Summary The selection of animals infected with the bovine leukaemia virus (BLV) is performed by the immunological detection of antibodies against the virus, commonly using the antigen gp51. Furthermore, research is being carried out to develop protective vaccines against BLV that have gp51 as their main component. Taking both of these factors into account, it is clear that there will be an increasing requirement for the virus antigen gp51 for some time to come. The permanently BLV‐infected foetal lamb kidney cell line FLK/BLV (and its sublines) has been proved to be the most useful culture for the mass production of the virus antigen. Stable cell lines producing higher quantities of BLV antigen have not been established, either by subcloning of the FLK/BLV or by infection of other permanent cells with BLV. Here, a report is made on efforts to increase the expression of gp51 in BLV‐infected cells via the additional expression of homologous transactivating virus protein tax. Selectable tax expression vectors that integrate into the host cell genome were constructed using BL provirus DNA fragments. Highly productive FLK/BLV cells were transfected with these vectors. Following selection with G 418, gp51‐producing cell lines were established and tested for their productivity for several months. Some tax‐vector‐containing cell lines have produced 1.5‐2 times more gp51 than the highly productive parental control cell line FLK/BLV 44‐1.

Characterization and application of recombinant Bovine Leukemia Virus Env protein

“…BLV serological diagnostic tests are principally based on gp51 antigen traditionally produced in an ovine BLV persistently infected cell line, FLK 80 , 81 . Production of high amounts of FLK-gp51 antigen requires partial purification and concentration and is time-consuming, expensive and laborious 82 .…”

Establishment of a new bovine leukosis virus producing cell line

“…Although many attempts have been made either to improve the antigen-producing properties of existing permanent bovine leukosis virus (BLV) expressing cell lines or to generate corresponding new lines (Graves and Ferrer, 1976;Mamoun et al, 1981;Altaner et al, 1985;Altanerova et al, 1989;Wagner et al, 1995), the cell line FLK/BLV still is the one that is used mainly for BLV antigen production for commercial diagnostic test kits. This line was established by cocultivation of fetal lamb kidney (FLK) cells with lymphocytes of an infected cattle in the USA (van der Maaten and Miller, 1976).…”