HPV detection rate in saliva may depend on the immune system efficiency

BACKGROUND: Human papilloma virus (HPV) has been established as a major etiological factor of anogenital cancer. In addition, HPV has also been implicated in oral carcinogenesis but its detection rates appear to be highly variable, depending on the patient population tested, the molecular methodology used, as well as the type of oral specimen investigated. For example, saliva is an oral fluid that may play a role in HPV transmission, although the detection rates of the virus are lower than tissue. Recent evidence has indicated that HPV-related pathology is increased in the oral cavity of human immunodeficiency virus (HIV)-positive individuals. In order to investigate whether the presence of different HPV types in saliva depends on immune system efficiency, oral fluid samples of patients with oral cancer and without any known immune deficiency were compared with those of HIV-positive individuals. PATIENTS AND METHODS: Saliva samples were collected from 68 patients with oral squamous cell carcinoma and 34 HIV seropositive individuals. HPV DNA sequences were detected by L1 concensus polymerase chain reaction (PCR), followed by restriction fragment length polymorphism (RFLP) analysis and DNA sequencing for HPV typing. RESULTS: HPV DNA was detected in 7/68 (10.3%) of the oral cancer patients and in 12/34 (35.3%) of the HIV-positive individuals, a highly significant difference (p = 0.006; odds ratio 4.753; 95% confidence interval 1.698-13.271). Among HPV-positive samples, the prevalence of HPV types associated with high oncogenic risk was similar in oral cancer and HIV-positive cases (71.4% and 66.7%, respectively). In both groups, the most common HPV type was high-risk 16 (50% and 42.8%, respectively). CONCLUSION: Although a similar pattern of HPV high-risk types was detected in oral cancer and HIV-positive cases, the quantitative detection of HPV in saliva significantly depended on immune system efficiency. Furthermore, the significantly increased detection rates of HPV in saliva of HIV-positive individuals may be associated with high risk for development of HPV-related oral lesions, including malignancy.