Detection of hepatitis B virus DNA in oral fluid by using an optimised nested PCR

Abstract

Background: Conventionally the detection of hepatitis B virus (HBV) DNA is carried out on serum using commercial or in house PCR assays. Oral fluid obtained by use of commercial collection devices offers several advantages compared to venepuncture: it is non invasive, painless, safe and less expensive. Methods: Seventy-three HBV DNA positive and 74 HBV DNA negative paired serum/oral fluid samples, drawn from patients visiting university hospitals, were analysed. The detection of HBV DNA in oral fluid was carried out through an optimised nested PCR with a 95% detection limit of 457 copies/ml Results: A clinical sensitivity and specificity of 69.9% (95%CI: 58.6%-79.2%) and 100% (95%CI: 95.1%-100.0%) respectively was achieved. A statistically significant association was found between the serum HBV DNA viral load and the detection of HBV DNA in oral fluid (p < 0.001). In samples with a minimum concentration of 10 5 copies/ml (high viraemia), it was possible to detect the virus in oral fluid in 91.8% (95%CI:80.8%-96.8%) of the cases. A concentration of 10 5 copies/ml being considered as the minimum level needed for the transmission of HBV via needlestick or mucosal scratch, the optimised nested PCR could be used in epidemiological surveys for mapping of active replicating carriers. Conclusion: An optimised nested PCR for HBV detection, with a 95% detection limit of 457 copies/ml and a sensitivity of 91.8% in patients with a minimum serum concentration of 10 5 copies/ml, was developed. The use of serum remains the golden standard for individual diagnosis, monitoring of antiviral treatment or detection of occult infections. However, oral fluid sampling by oracol collection device offers through all its advantages versus venepuncture a good alternative in epidemiological and surveillance surveys.