The role of lipoproteins in EBV early antigen induction in Raji cells

Abstract

Synthesis of the Epstein-Barr virus (EBV) associated early antigen (EA) can be induced by a variety of agents in Raji cells, a latently EBV-infected Burkitt lymphoma line. We investigated the role of lipoproteins in this EA induction system. Cell growth was not affected by lipoprotein-deficiency, but EA induction by most combinations of the inducers TPA (tetradecanoyl-phorbol-acetate), IdU (iododeoxyuridine), n-BA (n-butyric acid), anti-IgM and EA inducing factor (EIF), was greatly reduced. Only the inducer combination TPA/n-BA was completely independent of the presence of lipoproteins, indicating a different induction pathway. Removing the lipid moieties of the culturing serum did not result in reduced EA induction. Thus, the lowered EA inducibility in lipoprotein-deficiency is due to the absence of the protein moiety (apolipoprotein). Addition of HDL or VLDL partially reconstituted the original EA inducibility, whereas LDL had no effect. Lipoproteins were particularly important during the first 4 hours of induction, the phase where inducers may act on cell membrane structures (e.g., receptors). But lipoproteins were also required throughout the incubation period, even in a late and inducer independent phase.

Studies on the epidemiology of child infections in the Bari area (South Italy) VII. Epidemiology of Epstein-Barr virus infections

“…IgG to EA were studied similarly by use of acetone-fLxed Raji cells activated by IUdR and TPA (12-0-tetradecanoyl-phorbol-13-acetate, SIGMA Chemical, USA) (5,13). Detection of antibodies against EBNA was performed by anticomplement acetone-metanol fixed Raji cells (12).…”

Epstein-Barr-Virus-Associated Lymphoproliferative Syndrome in Severe Combined Immunodeficiency: Establishment of a Lymphoblastoid Cell Line as an in vitro Model for Biological and Therapeutic Studies

“…Induction, assessed as the percentage of EA-or VCA-positive cells, was then dependent on the concentration o f the latter inducer with a sigmoid dose-response plot. This assay system has been described before [29]. Briefly, aliquots of 3.5 x 105 cells/ml in standard culture medium were supplemented with 50 pg/rnl iodo-deoxyuridine (IdU, Sigma) as basic inducer and 1:2 serially diluted 12-O-tetradecanoylphorbol-13-acetate (TPA, Sigma), with concentrations ranging from 0.08 to 20 ng/ml.…”