Herpesviruses and Bacteria in Periapical Infectious Lesions

Objectives: Similarly to periodontitis, herpesviruses and bacteria may cooperate in the etio-pathogenesis of periapical pathosis. This study determined the rate of transcription of human cytomegalovirus (HMCV), Epstein-Barr virus (EBV) and herpes simplex virus (HSV), and the presence of bacterial species in 22 symptomatic and 5 asymptomatic periapical lesions. Methods: Periapical samples were collected in conjunction with periapical surgery. RNA was isolated from periapical tissue by using a guanidinium isothiocyanate-acid phenol procedure (TRIZOL LS Reagent, GIBCO BRL, Rockville, MD). cDNAs were generated from highly conserved regions of the test viruses using the RT-PCR-100 amplification kit (Sigma-Aldrich, St Louis, MO). Standardization of PCR primer sensitivity and validation was carried out according to established methods. Amplification products were identified by agarose gel electrophoresis. Bacterial samples were obtained using sterile paper points and transported in VMGA III medium. Bacterial identification was carried out by means of conventional anaerobic culture techniques. Results: HCMV transcript was detected in 21 (95.5%) symptomatic lesions and in 1 (20%) asymptomatic lesion. EBV transcript was demonstrated in 17 (77.5%) symptomatic lesions but not in any asymptomatic lesion. HCMV and EBV dual transcription, which occurred preferentially in large sized radiographic lesions, was detected in 16 (72.7%) symptomatic lesions but not in any asymptomatic lesion. HSV transcription was not found in any lesion studied. All but one asymptomatic lesion revealed bacterial growth. The most frequently isolated bacteria were Fusobacterium species, Peptostreptococcus micros and Actinomyces species. Conclusion: The present data suggest that HCMV and EBV participate in the pathogenesis of periapical symptomatic lesions. Herpesviruses may produce periapical pathosis as a direct result of viral infection and replication, or as a consequence of virally induced impairment of the host defense and subsequently increased virulence of resident bacterial pathogens.