[The roles of saliva testing for preventing hepatitis B virus spreading].

Objective: To discuss the significance of testing hepatitis B virus (HBV) from saliva in HBV patients.

Methods: HBV DNA content in serum and saliva of 200 HBV patients and 20 healthy subjects were detected by fluorescence quantitative polymerase chain reaction. According to the serum level of HBV content, four groups were divided: control group A, group B negative, low virus C (1 x 10(3) - 1 x 10(5) copies/ml) and high-group D ( > 1 x 10(5) copies/ml). The relationship of serum and virus content in saliva was analysed.

Results: Of 200 HBV cases, 180 were found HBV DNA in serum with positive rate of 90.0%; while 145 were found HBV DNA in saliva with positive rate of 72.5%, and there was no significant difference (chi2 = 1.35, P > 0.05). The significant difference was observed in testing serum and saliva in Group C (100.0% vs. 38.5%; Z = 14.11, P < 0.01). In group D, there was no significant difference found either (100.0% vs. 83.8%; chi2 = 1.05, P > 0.05). Group D virus serum had a high average level of (6.63 +/- 1.55) log copies/ml virus and in the saliva had an average level of (5.21 +/- 1.85) log copies/ml; saliva had serum viral load lower than an order of magnitude average. No HBV DNA was found in serum or saliva from 20 health subjects.

Conclusion: When the serum contains a high content of HBV DNA virus, the content of saliva HBV DNA virus should be likely high, which might pose a threat of source of infection. A precise quantitative detection of HBV DNA in saliva might be used as evaluation of the level of virus in the body copy for judgment of infection.