Evaluation of the effect of smokeless tobacco purified products and extracts on latent Epstein-Barr virus.

Numerous chemical tumor promoters induce latent Epstein Barr virus (EBV) to active replication. The effect of smokeless tobacco purified products N-nitrosonornicotine (NNN), 4-(N-methyl-N-nitrosamine)-1-3-pyridinyl)-1-butanone (NNK), benzo(a)pyrene (BaP), and smokeless tobacco extracts (dry snuff, moist snuff, and loose leaf tobacco) was tested for induction of latent EBV in Raji cells using fluorescence-activated cell sorter flow cytometry detection of the restricted component of EBV early antigen (EA-R). Concentrations of smokeless tobacco purified products or preparations were used that have carcinogenic effects in animal cell lines. There was no discernible effect for the 6-7-day duration of treatment on viability of Raji cells, or on induction of latent EBV in Raji cells. Results were comparable using paraformaldehyde- or acetone-fixed cells. There does not appear to be an in vitro effect of smokeless tobacco constituents on EBV-infected lymphocytes that may contribute to development of oral cancers.