HUMAN HERPESVIRUS-6 (HHV-6) DNA AND VIRUS-ENCODED ANTIGEN IN ORAL LESIONS

Archival oral tissues comprising 51 squamous cell carcinomas, 18 non-m alignant lesions and 7 normal mucosa samples were investigated for hum an herpesvirus-6 (HHV-6)-encoded antigens and HHV-6 DNA. The virus-spe cific antigens were detected by an immunohistochemical method using mo noclonal antibodies. Two further techniques used for HHV-6 DNA detecti on included the polymerase chain reaction (PCR) with virus-specific pr imers and in situ hybridization using digoxigenin-labelled oligonucleo tides specific for HHV-6A and HHV-6B genotypes. A high proportion (79- 80%) of the squamous cell carcinomas were positive for HHV-6 with the various detection methods. In cases of lichen planus and leukoplakia a high prevalence rate (67-100%) was noted with in situ hybridization a nd immunohistochemical techniques but a lower proportion (22-33%) was detected with the PCR method. All 7 normal tissues tested were negativ e for HHV-6. The HHV-6 variant B was found in 60% of the oral carcinom a,tissues analysed. The study demonstrates the frequent presence of HH V-6 in neoplastic and nonmalignant lesions of the oral cavity. While t he role of HHV-6 in oral mucosal tissues remains to be determined, the in vitro tumorigenic potential of the virus suggests a possible role in the etiopathogenesis of oral lesions.