Coexpression of HPV-16 and -11 L1 genes using the bivalent recombinant baculovirus and VLPs assembled by L1 proteins

Objective To make HPV-16-11 bivalent engineering vaccine coexpression of HPV-16 and -11 L1 using the bivalent recombinant baculovirus and Virus-like particles(VLPs) assembled by the L1 proteins. Methods The locally prevalent HPV-16 L1 gene was sub-cloned and pBluescript-HPV-16L1 was constructed and sequenced. The HPV-16 L1 gene was inserted into the downstream of the strong promoter pho1. The locally prevalent HPV-11 L1 gene from pSP73-HPV-11L1 plasmid was inserted into the downstream of the weak promoter p10 of baculovirus shuttle vector pFastBacDual. The HPV-16 and HPV-11 L1 proteins were coexpressed in Bac-to-Bac baculovirus insect cell Sf9 expression system and were identified by Western blot. VLP in insect cells were identified by transmission electron microscope (TEM). Results Baculovirus shuttle vector pFastBacDual-HPV-16L1-HPV-11L1 was correctly constructed. Then, the recombinant baculovirus Bac/HPV-16L1-11L1 was generated by action of transpon in E. coli strain, DH10Bac. The bacmid/HPV-16-HPV-11L1 was generated. HPV-16 L1 and -11 L1 proteins from the insect cells Sf9 infected with the recombinant baculovirus were identified and a molecules relative mass(Mr) 56×10~3 band composing both HPV-16 and -11 proteins was shown in SDS-PAGE and Western blot. TEM observation showed abundant VLPs in the Sf9 cells. Conclusion We have successfully constructed the recombinant baculovirus Bac/HPV-16L1-11L1 using locally prevalent HPV-16 and -11. TEM results indicated that the proteins assembled into VLPs. After immunization using VLPs, the anti-L1 proteins antibodies were detected in serum of immunized BALB/c mice. The coexpression of the proteins of different HPV types may provide new tools for prevention of HPVs infection.