Effect of the arginine analog canavanine on the synthesis of Epstein-Barr virus-induced proteins in superinfected Raji cells

Down-regulation of spontaneous Epstein-Barr virus reactivation in the P3HR-1 cell line by L-arginine

We tested the hypothesis that inhibition of Epstein-Barr virus (EBV) reactivation is controlled in part by nitric oxide (NO) generated from L-arginine (Arg). The spontaneous reactivation of EBV in the Burkitt's lymphoma (BL) cell line P3HR-1 was inhibited when the cells were cultured in L-Arg-supplemented medium. The expression of EBV early antigen (EA), immediate-early BZLF1 mRNA and the protein ZEBRA, and production of infectious virus were reduced by L-Arg supplementation in a dose-dependent manner. We demonstrated that inducible NO synthase (iNOS) mRNA was constitutively expressed in P3HR-1 cells, as quantitated by the reverse transcription-polymerase chain reaction. L-Arg supplementation enhanced iNOS and NOx expression in the cells. A specific NOS inhibitor, NG-monomethyl-L-Arg enhanced the expression of ZEBRA and early BMRF1 protein EA-D in the cells. L-Arg supplementation also inhibited the spontaneous EBV reactivation in another BL cell line EB1 and a B lymphoblastoid cell line OB. These results indicated that L-Arg induces iNOS and generates NO, which inhibits EBV reactivation in EBV-positive cells.

The regulated expression of Epstein-Barr virus: evidence that the transition from primary to secondary protein synthesis in Raji cells superinfected with Epstein-Barr virus requires the synthesis of new RNA

In the presence of canavanine and the absence of arginine, superinfected Raji cells synthesize a limited spectrum of proteins (primary proteins). After the removal of canavanine at 8 h post infection, the cells proceed after a lag phase of 2-3 h to synthesize a second group of proteins. The appearance of these proteins can be prevented by addition of actinomycin-D to the chase media, suggesting that active primary proteins are required for the synthesis of new mRNA coding for the secondary proteins.

Mapping of Epstein-Barr virus proteins on the genome by translation of hybrid-selected RNA from induced P3HR1 cells and induced Raji cells

RNA was isolated from induced P3HR1 cells which synthesize Epstein-Barr virus (EBV) particles and therefore a full set of early and late antigens and from induced Raji cells which synthesize only early EBV proteins and hybridized to cloned EBV-DNA fragments spanning the entire genome. Bound mRNA was eluted and translated in vitro with rabbit reticulocyte lysate. The translation products were analyzed on SDS-polyacrylamide gels either directly or after immunoprecipitation with human sera. Most proteins could be mapped to short defined regions of the EBV genome using short restriction fragments and overlapping sheared fragments and there is evidence of splicing for some mRNA species. The synthesis of five early proteins can be seen only with hybrid-selected RNA from induced Raji cells. These mRNAs seem to be enriched in the cells restricted to early antigen synthesis.