Animals, Apoptosis, Chronic Disease, Cytomegalovirus Infections, Disease Models, Animal, Fas Ligand Protein, Female, Gene Transfer Techniques, Genetic Therapy, In Situ Nick-End Labeling, Membrane Glycoproteins, Mice, Mice, Inbred C57BL, Mice, Inbred MRL lpr, Mice, Mutant Strains, Muromegalovirus, RNA, Messenger, Salivary Glands, Sialadenitis, Sjogren's Syndrome