Abstract: ObjectiveTo screen and clone the target genes transactivated by hepatitis B virus （HBV） Pre-S2 protein in order to pave away for elucidating the pathogenesis of HBVinfection.MethodsHBVPre-S2 coding DNAfragment was amplified by polymerase chainreaction （PCR） using G3767 plasmid containing the full length of HBVgenome as a template. An expressive vector of pcDNA3.1 Pre-S2 was constructed with routine molecular biological methods. HepG2 cells were transfected with pcDNA3.1 （-） and pcDNA3.1 Pre-S2, respectively, using the FuGENE6 transfection reagent. Total RNA was isolated and reverse transcribed. cDNAs were subjected tomicroarray screening with 1 152 cDNA probes.ResultsFull length sequences of the obtained genes were searched from GeneBank.One of the obtained genes was a newgene with unknown functions. The newgene that has no homology with known genes in GeneBankwas confirmed with its full length DNA cloned by polymerase chain reaction （PCR）. Reverse transcription PCR （RT-PCR） was usedto amplify the new gene, PS2TP1, from mRNA of HepG2 cells （The access number of PS2TP1 gene Gen-Bank is AY561706）.ConclusionHBV Pre-S2 protein is a transcriptional transactivator. The results of our study may help to find the molecular mechanismunderlying the transactivating effects of HBV Pre-S2 protein and to develop new therapies for chronic hepatitis B.