Effect of tar condensate from smoking tobacco and water-extract of snuff on the oral mucosa of mice with latent herpes simplex virus.

Upper lips were inoculated with virus to establish a latent infection in the trigeminal ganglia. During the latent period, tobacco smoke tar condensate or water-extract of snuff were topically applied to the primary inoculation site for two or three consecutive months. Tar condensate induced re-activation of latent HSV in the ganglia of 10 to 20 per cent of animals but snuff extract did not. Infectious virus was also detected in lips after the chronic application of tar condensate in 10 per cent of animals. Three months' exposure to tobacco produced epithelial dysplasia and other changes in a significant number of latent HSV-infected mice, whereas tobacco alone did not induce dysplasia in the labial epithelium of uninfected mice.