Optimization of a rapid and sensitive nucleic acid lateral flow biosensor for hepatitis B virus detection

Abstract

Background and Objective Rapid on-site testing with low sample volume and point-of-care diagnostics are very useful for preventive measures against hepatitis B virus. Therefore, the aim of this study is to develop a rapid, accurate, and cost-effective lateral flow biosensor for convenient HBV nucleic acid detection at the point-of-care. Methods Clinical serum samples with HBV-positive real-time PCR assays were used for the experiments. Spin column nucleic acid purification and serum heat treatment were used for sample preparation. A 250 bp fragment of the HBV polymerase gene was amplified with 3 pairs of specific biotin- and FITC-labeled LAMP primers. Different incubation temperatures (64-68° C) and times (30 min, 45 min, and 1 h) were explored for optimal LAMP assay, and results were assessed by fluorometric analysis, white turbidity, and lateral flow assay. Ready-to-use Milenia HybriDetect1 strips were used to visualize the LAMP amplicons. Subsequently, 10-fold serial dilutions of a secondary standard containing 108 IU/ml viral load were used to evaluate lateral flow biosensor performance. Results The LAMP reaction was optimized at 67 ◦C, and appreciable turbidity was achieved after 30 minutes of incubation. Templates from 108 IU/ml to 101 IU/ml exhibited distinct test bands when spin column approach was used as the purification method. However, the minimum viral load detectable by lateral flow was 103 IU/ml when serum samples were treated with heat and the supernatant was directly used for LAMP. The result shows that the developed LAMP-LF assay was able to detect a viral load of 101 IU/ml only in 66.6% of cases. Conclusion The LAMP-LF assay is a potential solution for HBV testing in resource-limited settings. Overall, our study demonstrated that the integration of LAMP - LF assay can be a plausible approach for point-of-care application with high sensitivity and accuracy. However, direct amplification without DNA purification is excluded and may lead to poor performance of the approach.