Molecular characterization of multiple putative novel hepatitis B virus spliced DNA from a chronic hepatitis B patient

Spliced hepatitis B virus (HBV) RNA has been reported to affect the viral life cycle and progression of liver disease. As much as 30% of HBV RNA are spliced in infected cells, and some can be reverse transcribed to spliced DNA. To date, only a small number of spliced DNA have been identified and the majority require further investigation. This study aimed to identify the types of spliced DNA from the sera of a chronic hepatitis B patient. HBV DNA was isolated from the serum, and both full-length and spliced DNA were amplified by PCR. The amplified PCR products were then subcloned and sequenced using a Sanger sequence analysis. As a result, 19 types of spliced DNA were identified, 11 of which were assumed to be putative novel spliced DNA. These spliced DNA were doubly spliced with varied splice donor sites and splice acceptor sites. In addition to the frequently detected HBV SP1, SP2, and SP4, we also identified 11 putative novel spliced DNA in the serum. These findings indicate the complexity of HBV RNA splicing during viral life cycle.