Study On Trans-regulation Effects Of HBV Surface Proteins

Hepatitis B virus (HBV) infection causes acute and chronic hepatitis. Acute infections may produce serious illness, and approximately 0.5% terminate with fatal, fulminant hepatitis. Chronic infections may also have serious consequences, HBV is considered to be a major etiological factor in the development of human hepatocellular carcinoma (HCC), one of the most frequent fatal malignancies worldwide, and worldwide deaths from HCC caused by HBV infection probably exceed one million per year. Epidemiological studies have demonstrated an approximately 100-fold increase in the relative risk of HCC among HBV carried compared to noncarriers. So, understanding of the precise mechanism of HBV carcinogenesis is a vital prerequisite for the development of antiviral concepts and treatment for HCC.HBV is a small, enveloped DNA virus of the hepadnavirus family, its genome is a relaxed-circular, partially duplex DNA of 3.2 kb, characterized by four overlapping ORFs (S,C,P, X). The S-ORF consists of a single open reading frame divided into three coding regions: pre-S1, pre-S2 and S, each starting with an in-frame ATG codon. Through alternate translational initiation at each of the three AUG codons, a large (LHBs; pre-S1+pre-S2+S), a middle (MHBs; pre-S2+S) and a small (SHBs;S) envelope glycoprotein can be synthesized.To study the trans-regulation effects of surface proteins, the recombined expression plasmid, pcDNA3.1(-)-SHBs, pcDNA3.1(-)-PreS1 and pcDNA3.1(-)-PreS2 were constructed, respectively. HepG2 cells were transfected, and pcDNA 3.1(-) empty vector was used as control. The mRNA was isolated from HepG2 cells, respectively, and suppression subtractive hybridization (SSH) method was employed to analyze the differentially expressed DNA sequence between the two groups. The obtained product was subcloned into T/A plasmid vectors to set up the subtractive library. Amplification of the library was carried out with E. coli strain DH5a. The cDNA was sequenced and analyzed in GenBank with Blast search after PCR. At the same time, Microarray was employed for detecting and analyzing of mRNA from the HepG2 cells transfected. The obtained sequences may be target genes transactivated by HBV surface proteins, among which some...