386 HEPATITIS B RNA SPLICING SUPPORTS VIRAL REPLICATION THROUGH FUNCTIONING AS DEDICATED CORE mRNA

Abstract

mutants isolated from serial sera were amplified and converted into the replication-competent HBV 1.2mer constructs. Each construct was analyzed for in vitro drug susceptibility assay by southern. We made a series of mutant clones and determined the replication ability and resistance to antiviral agents. Results: Conserved mutations in rt204, rt181, rt236, and rt233 were identified during the viral breakthrough. In vitro study showed the effect of rtA181T mutation on viral replication and drug resistance is dependent on the mutation in overlapping surface gene. The rtA181T mutant harboring surface stop (rtA181T/sW172*) showed a decrease in viral replication and increase in drug resistance compared to the rtA181T mutant harboring surface mutation (rtA181T/sW172S). Moreover, the rtA181T/sW172* mutant exhibited a secretion defect of viral particles. The rtI233V mutation which emerged during adefovir therapy reduced the viral replication and conferred resistance to adefovir. However, the rtI233V mutation did not affect the viral replication and drug resistance of rtA181T/sW172* mutant. Conclusions: The consequence of rtA181T mutation in viral replication of HBV and drug resistance is dependent on the mutations in overlapping surface gene. The rtI233V mutation affects the replication ability and resistance to adefovir.