The effect of saliva specimen collection, handling and storage protocols on hepatitis C virus (HCV) RNA detection by PCR.

OBJECTIVES: Commercial assays can now be adapted to detect salivary anti-hepatitis C virus (HCV) antibodies, increasing the potential of saliva as a non-invasive diagnostic specimen suited to surveillance and epidemiological studies. However, current diagnostic algorithms involve confirmation of HCV infection by RT-PCR. Manipulation and storage conditions of serum can influence the stability of viral RNA. This study examined whether varying specimen collection, handling and storage protocols also affected subsequent HCV RNA detection by RT-PCR applied to saliva specimens. METHODS: Whole unstimulated saliva, together with saliva samples collected in two commercially available devices (Salivette and Omnisal) were obtained from 50 HCV seropositive intravenous drug users. The specimens were subjected to a number of handling and storage conditions, including heat treatment and prolonged storage, then examined for HCV RNA by RT-PCR using primers derived from the 5' non-coding region (5'NCR). RESULTS: HCV RNA was detected in saliva samples from 25 (50%) of the patients. No single collection device or handling procedure identified all the subjects with HCV RNA positive saliva though whole saliva yielded the greatest number of positive results. CONCLUSIONS: Collection and processing of saliva specimens for RT-PCR analysis is complex. At present, detection of salivary HCV RNA by PCR is not sufficiently sensitive for use as a diagnostic tool in epidemiological studies.

Predominance of HCV type 2a in saliva from intravenous drug users.

Paired serum and saliva samples were collected simultaneously from 50 intravenous drug users with serologically proven hepatitis C virus infection. The oral health of the volunteers was also assessed. Hepatitis C virus RNA was detected by nested PCR, employing primers from the 5' noncoding region. Positive PCR products were sequenced using the Sequenase PCR Product Sequencing Kit (Amersham Life Sciences). HCV RNA was detected in 33 (66%) of the 50 serum samples. HCV RNA was detected in 19 (57.6%) of the corresponding 33 saliva samples. There was no correlation between oral health status or HIV seropositivity and the detection of HCV in saliva. However, subjects with HCV in their saliva were significantly more likely to complain of xerostomia (P < 0.05). Isolate genotypes were identified in paired serum and saliva of 15 intravenous drug users. HCV genotypes 1, 2, 3 and 6 were detected in both specimens. In seven cases, a differing HCV genotype was found in serum compared to the paired saliva specimen. The distributions of genotypes in serum and saliva were very different, with genotype 2a more common in saliva than serum (P < 0.005). These data suggest that in some cases the source of salivary HCV may not be serum transudation along the periodontal membrane or across damaged mucosa, and that an alternative local source, possibly the salivary glands themselves, should be considered.

Detection of antibodies against hepatitis C virus in saliva: a marker of viral replication.

Hepatitis C surveillance has been restricted owing to the lack of a sensitive antibody assay for saliva. The aim of our study was to develop and evaluate a screening assay for hepatitis C antibody in saliva specimens. Serum/saliva pairs were collected from 115 hepatitis C-positive patients. A modified hepatitis C antibody assay for saliva was developed and linked to testing carried out in the diagnostic laboratory. Correlation between the presence of antibody in serum and in saliva was poor (100% vs 85%). However, of 98 patients who were saliva antibody positive, 96 (98%) were also serum hepatitis C RNA positive and two (2%) were serum hepatitis C RNA negative. Hence, the correlation between a positive salivary antibody test and the serum hepatitis C RNA status of intravenous drug users suggests that this test could be used as a surrogate marker for hepatitis C viraemia in epidemiological studies.