Detection of Herpesviruses from Endodontic Patients Exhibiting Apical Periodontitis

Objectives: Apical periodontitis is an inflammatory disease caused by pathogenic bacteria and potential co-infection with latent herpesviruses. Apical periodontitis may be symptomatic or asymptomatic for pain. The objectives of this study are to identify herpesviruses, including Human Cytomegalovirus (HCMV), Epstein-Barr virus (EBV), Varicella Zoster virus (VZV), and Herpes Simplex virus (HSV-1), in periapical tissue obtained from patients presenting with apical periodontitis of endodontic origin, and to provide evidence for active transcription of herpesviruses in endodontic pathosis.

Methods: Periapical samples were aseptically removed from 10 patients exhibiting apical periodontitis, including six symptomatic and four asymptomatic individuals. To detect herpesvirus DNA and RNA, the latter indicative of active viral transcription, we conducted nested polymerase chain reaction (PCR) and reverse transcriptase-PCR, respectively. We also conducted immunocytochemical analysis of periapical tissue obtained from a patient exhibiting asymptomatic apical periodontitis.

Results: Four patients, including one symptomatic patient and three asymptomatic patients, had periapical tissue samples positive for EBV. Two of these three asymptomatic samples exhibited active EBV transcription. Three patients, including one with symptomatic and two with asymptomatic periodontitis, had tissue positive for HCMV, with only one asymptomatic sample undergoing active HCMV transcription. Two patients, including one with symptomatic and one with asymptomatic apical periodontitis, had tissue positive for HSV-1, with both samples undergoing active HSV-1 transcription. No tissue samples were positive for VZV. Immunocytochemical analysis of an asymptomatic tissue sample revealed intense, punctate labeling with anti-HCMV, with no detection of specific labeling with anti-EBV. Double labeling demonstrated overlap of anti-HCMV positive puncta with anti-neurofilament positive fibers.

Conclusions: We conclude that herpesviruses, including HCMV, EBV, and HSV-1, are present, and in some cases are undergoing active viral transcription in patients exhibiting apical periodontitis of endodontic origin, and that significant proportions of HCMV may be associated with nerve fibers in infected periapical tissue.