Real-time polymerase chain reaction quantification of human cytomegalovirus and Epstein-Barr virus in periodontal pockets and the adjacent gingiva of periodontitis lesions

Abstract

Background: Genomic sequences of human cytomegalovirus (HCMV) and Epstein-Barr virus (EBV), two herpesviruses, can frequently be detected in periodontal pockets of progressive periodontitis lesions, but the prevalence and load of the two viruses in gingival tissue are unknown. This study determined levels of HCMV and EBV DNA in the periodontal pocket and in the adjacent gingiva of periodontitis lesions using a real-time polymerase chain reaction (PCR) assay.

Material and methods: A total of 20 systemically healthy periodontitis patients participated in the study. Nine patients below 35 years of age were tentatively diagnosed as having aggressive (early onset) periodontitis, and 11 patients 36-56 years of age as having chronic (adult) periodontitis. Clinical parameters were evaluated using established methods. Using periodontal curettes, specimens were harvested from 6-10 mm periodontal pockets and from the adjacent inflamed periodontal pocket wall. A 5'-nuclease (TaqMan) real-time PCR assay was used to identify and quantify genomic copies of periodontal HCMV and EBV.

Results: HCMV DNA was detected in 78% of subgingival and 33% of gingival tissue samples from aggressive periodontitis lesions, but only in 46% of subgingival and 9% of gingival tissue samples from chronic periodontitis lesions. In aggressive periodontitis, HCMV subgingival and gingival tissue counts were positively correlated with periodontal pocket depth and probing attachment loss at sample sites (p<or=0.03; Spearman's rank correlation coefficient test). EBV DNA was identified in 89% of subgingival and 78% of gingival tissue samples from aggressive periodontitis lesions, but only in 46% of both subgingival and gingival tissue samples from chronic periodontitis lesions. In aggressive periodontitis, positive correlations were found for EBV subgingival counts and periodontal pocket depth at sample sites (p=0.04; Spearman's correlation) and for EBV gingival tissue counts and whole mouth mean gingival index (p=0.04; Spearman's correlation). In chronic periodontitis, statistical significance was only found between EBV subgingival counts and periodontal pocket depth at sample sites (p=0.04; Spearman's correlation). HCMV-EBV coinfection was revealed in 78% of aggressive periodontitis lesions but only 27% of chronic periodontitis lesions (p=0.03; chi-squared test). Also, seven of nine aggressive periodontitis patients but only three of 11 chronic periodontitis patients revealed more than 10,000 copies of HCMV or EBV in subgingival or gingival tissue samples (p=0.03; chi-squared test). Four of six patients having mean periodontal pocket depth at sample teeth (four study sites per tooth)>6 mm, but none of 14 patients having mean pocket depth at sample teeth<or=6 mm revealed more than 100,000 copies of HCMV or EBV in subgingival or gingival samples (p=0.001; chi-squared test). In periodontitis lesions demonstrating herpesviruses in paired subgingival and gingival tissue samples, the tissue samples showed the higher HCMV copy counts in three of four patients and the higher EBV copy counts in six of eight patients.

Conclusions: The elevated occurrence of HCMV and EBV DNA copies in periodontal pockets and in the gingival tissue of aggressive periodontitis lesions relative to chronic periodontitis lesions, and the increase in herpesvirus counts with increasing severity of periodontitis lend substantial support to a periodontopathic role of the two viruses. Real-time PCR determination of herpesvirus DNA in periodontal sites may become a promising marker to monitor the course of destructive periodontal disease. Herpesviruses and bacteria, now mostly studied in isolation, may cooperate synergistically in the development of periodontitis, and should probably be considered as a pathogenetic consortium in future investigations of periodontal infections.