Hepatitis C Virus in Saliva

To investigate the prevalence of hepatitis C virus in saliva, the saliva of a group of haemophiliacs and blood donors, who were previously shown to be anti HCV positive by second generation immunoassay and a recombinant immunoblot, was examined using reverse transcription and the polymerase chain reaction. Both studies indicated that HCV was present in the saliva of a proportion (47.6% and 34% respectively) of each study group. With a view to utilizing the polymerase chain reaction on saliva as a routine diagnostic tool for the detection of HCV, a revised protocol was sought, from the numerous procedures available, to reduce the sophisticated technique to a reproducible, reliable method. All aspects of the entire protocol from beginning to end were considered. HCV RNA extraction was assessed using two commercially available kits, in addition to the more traditional lysis with a chaotrophic agent followed by organic extraction and ethanol precipitation. Two procedures involving separate reverse transcription and the polymerase chain reaction were compared with a combined one step reverse transcription and polymerase chain reaction, to establish a protocol ensuring maximum amplification while reducing the possibility of false positive results. Finally, a sensitive and specific method was sought that would enable accurate detection of the desired product in a non-laborious manner. The appropriateness of the polymerase chain reaction performed on saliva samples as an alternative to blood was evaluated among a group of HCV infected blood donors enrolled in a trial of interferon. Observation and treatment patients were monitored using biochemical and virological markers. Blood and saliva were collected in parallel and tested for HCV RNA. Results indicated that saliva was not a suitable alternative to blood for determining response to treatment. In every study, both whole saliva and oral fluid collected in commercially available devices were obtained. HCV RNA could be detected in both specimen types but often not in parallel. These discrepancies may have resulted from deficiencies in the sample handling protocols. It is likely that specimen processing and storage conditions may influence the stability of HCV RNA. This was evaluated by studying saliva samples collected from known HCV seropositive intravenous drug users, which had been subjected to a number of handling and storage conditions. No single method was shown to be appropriate for both saliva and oral fluid. The evaluation of paired serum and saliva samples for HCV RNA indicated that some individuals had HCV RNA present in saliva but not in blood. DNA sequencing was employed to confirm the presence of HCV RNA in saliva and to genotype the isolates amplified. The presence of different subtypes and even genotypes in the mouth and serum was observed. The source of HCV within the mouth and the potential risk of transmission through saliva are discussed