Worldwide there are 350 million people persistently infected with hepatitis B virus (HBV). Therefore, the virus is one of the most common human pathogens and responsible for significant health problems of the world population. On account of sequence differences in the hepatitis B virus genomes they are classified into geno- and subgenotypes. The present work examined the molecular differences of genotypes A-I but could not find any differences for the selected markers. Furthermore, studies on subgenotype C2 showed that the T1653-variant had an influence on enhancer II. Various sizes of HBx transcripts were discovered. C2-variants have shown different effects on cellular gene expression profiles. Finally two genes were identified, e.g. Rap1A, which is increasingly expressed because of HBx.