Detection of Herpesviruses in Apical Abscesses of Endodontic Origin

Objectives: Acute apical abscesses are severe endodontic diseases. These may be caused by co-infection with pathogenic bacteria and latent herpes viruses. Periapical pathosis results in the destruction of the bone surrounding the apex of the root. This study screened for herpes viruses, including Human Cytomegalovirus (HCMV), Epstein-Barr virus (EBV), Varicella Zoster virus (VZV), and Herpes simplex virus (HSV-1), in aspirates obtained from patients presenting with acute apical abscesses of endodontic origin. Methods: 31 patients with an acute apical abscess were clinically examined and clinical data were recorded. Samples of abscesses were aseptically aspirated from these patients and used in viral DNA extractions. Primary and nested polymerase chain reactions (PCR) were performed using virus-specific primers and DNA isolated from cell-free virus preparations. Abscess fluids were filtered to remove residual immune cells and treated with DNase I to degrade cellular DNA prior to extraction of nucleic acids from virus particles and use in PCR. PCR products were visualized using gel electrophoresis. Results: From patients exhibiting concurrent spontaneous pain and periradicular rarefraction (n=29), 9 abscesses contained HCMV (31%) and 2 abscesses contained EBV (6.9%). One individual, who exhibited periradicular rarefraction but no spontaneous pain, contained HSV-1. No patients exhibited VZV. Cross amplification of viral targets using virus-specific primers and control viral DNAs was not detected. Primary PCR could only detect minimum viral DNA copy number of 10,000 copies. Due to the small copy numbers of virus particles present in the abscess samples, nested PCR was required for all viral detections. Conclusions: We conclude that herpes viruses, primarily HCMV and EBV, are replicated in patients exhibiting acute endodontic disease and are transmitted and released as virus particles in abscess fluid.