Progress of HBV infection in tree shrews of group A. The number on the top of each panel refers the name of animal. HBV DNA in serum and liver samples was detected by FQ-PCR. The result of HBV DNA detection was expressed as IU/ml in serum and as IU/μg liver DNA in liver. Serum HBsAg was detected by TRFIA and the result was expressed as ng/ml. Serum HBsAb, HBeAg, HBeAb and HBcAb were detected by ELISA and the results were expressed as “+” (positive), “-” (negative) or “±” (between positive and negative).