Anti-HBV effect of interferon-thymosin α1 recombinant proteins in transgenic Dunaliella salina in vitro and in vivo

The aim of the present study was to investigate the anti-hepatitis B virus (HBV) effect of interferon (IFN)-thymosin α1 (TA1) in a transgenic Dunaliella salina (TDS) system in vitro and in vivo. The toxicity of TDS in the HepG2.2.15 cell line was assessed using an MTT assay. The effect of TDS on the secretion of HBV early antigen (HBeAg) and HBV surface antigen (HBsAg) in culture supernatants was measured using ELISA. In addition, HBV-DNA was analyzed using quantitative polymerase chain reaction. Drug treatment experiments were performed in vivo on ducks congenitally infected with duck HBV (DHBV). The drug was administered once daily for 21 continuous days. Blood was drawn from all ducks prior to treatment, following treatment for 7, 14 and 21 days, and following drug withdrawal for 5 days. Serum DHBV-DNA was determined using quantitative PCR. In addition, the histology of duck liver tissues was assessed using hematoxylin and eosin, and orcein staining. The results demonstrated that TDS suppressed cell viability and HBsAg and HBeAg secretion in HepG2.2.15 cells. Furthermore, the treatment index values for HBsAg and HBeAg following TDS treatment were 2.96 and 3.07 respectively, which were greater than those of the IFN-α treated group. In addition, the DHBV-infected duck model experiments indicated that serum DHBV-DNA levels were significantly decreased in the group of TDS (20 g/kg) following treatment for 7, 14 and 21 days compared with the control group. Following withdrawal of the drug for 5 days, the levels of DHBV-DNA did not relapse in the medium and high dose groups of TDS (10 and 20 g/kg, respectively). Histological analysis of duck liver also demonstrated that TDS and IFN-α treatment alleviated inflammation and HBsAg signals in duck livers. In conclusion, TDS markedly suppresses HBV replication in vitro and in vivo and its anti-HBV effect is greater than that of IFN-α.