A construction strategy for a baculovirus-silkworm multigene expression system and its application for coexpression of type I and type II interferons

Liu, Xingjian; Yang, Xin; Mehboob, Arslan; Hu, Xiaoyuan; Yi, Yongzhu; Li, Yinü; Zhang, Zhifang

Likewise, an approximately 19 kDa protein band that reacted with an anti-chIFN-γ antibody was observed in reBm-Cαγ and reBm-Cγ expression samples. No corresponding immunoreactive protein was detected in the negative control sample from larval hemolymph infected with control BmNPV. Antiviral activity of recombinant IFNs was assayed utilizing a CPE inhibition assay with CEF cells. Recombinant IFN products could inhibit VSV-GFP infection in CEFs (Figure 3 ). The antiviral activity assay results indicated that the antiviral potential of reBm-Cα, reBm-Cγ, and reBm-Cαγ products were 3.26 ± 0.61 × 10 6 IU/mL, 5.08 ± 0.43 × 10 6 IU/mL, and 3.27 ± 0.50 × 10 7 IU/mL in hemolymph, respectively. These recombinant baculovirus expression products were then acid (pH 2.0) and heat treated (56°C). IFN-α is acid and heat resistant, but IFN-γ is acid and heat labile (Ho et al., 1975) . Therefore, the antiviral activity of the reBm-Cα product remained almost the same before and after treatment. The antiviral activity of the reBm-Cγ product declined to an undetectable level. The antiviral activity of the reBm-Cαγ product was still 5.78 ± 0.88 × 10 6 IU/mL, which was due to IFN-α activity. This activity was 2 times greater than that of the reBm-Cα product. This enhanced expression level of IFN-α must be due to p10 gene deletion in coexpression recombinant baculovirus (Hitchman et al., 2010) .