Detection of Hepatitis B Virus DNA among Chronic and potential Occult HBV patients in resource-limited settings by Loop-Mediated Isothermal Amplification assay.

Transmission of Hepatitis B Virus (HBV) usually occurs due to the transfusion of blood or blood products from chronic HBV (CHB) or occult HBV-infected (OBI) patients. Besides serological tests, e.g. HBsAg and anti- HBc (total), detection of HBVDNA is necessary for the diagnosis of OBI patients. Different nucleic acid tests (NATs) including real- time-Polymerase Chain Reaction (qPCR) are used to detect HBV- DNA. The NATs are expensive and require technical expertise which are barriers to introduce them in resource-limited settings. This study was undertaken to evaluate the use of Loop-Mediated Isothermal Amplification (LAMP) assay as an alternative to qPCR for the detection of HBV-DNA in CHB and potential OBI patients in resource-limited settings. Following the published protocols with some modifications, a LAMP assay was developed for detection of HBV-DNA by either using a heat block followed by detection in an agarose gel or using a qPCR thermocycler. The LAMP assay was applied to supernatant prepared from heat-treated serum collected from CHB and potential OBI patients. HBV viral load in serum was measured by qPCR using a single-step HBV-DNA quantification kit. Among 200 samples tested, qPCR was capable to detect HBV-DNA in 25.5% of cases, whereas LAMP assay detected HBV-DNA in 43.5% cases. The qPCR was able to detect 11 (9.16%) potential OBI cases, whereas LAMP assay identified HBV-DNA in 43 (35.83%) cases. In addition to tests for HBsAg and/or anti-HBc (total), detection of HBV-DNA by LAMP assay may aid in preventing post-transfusion HBV infection in resource-limited settings.