"Our observations raise the possibility that a very low number of copies of the tax gene may be harbored innocuously in cells within the oral cavity in some healthy individuals, but that this gene may play a role as a co-factor in the development of SS or other diseases of oral cavity"
http://www.ncbi.nlm.nih.gov/pubmed/10895371
More on this subject
Human T Cell Leukemia Virus Type I Expression in Salivary Glands of Infected Patients
http://jid.oxfordjournals.org/content/179/2/497.full