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Background Human papillomaviruses(HPVs)can infect squamous or mucosal epithelia and cause cervical cancer orgenital warts.Coinfection with multiple HPV types is a common finding of many epidemiological studies.Therefore,it isnecessary to develop a vaccine,which can eradicate established HPV infections and prevent other HPV infections.Inthis study,we generated chimeric virus like particles(cVLPs)composed of HPV-6b L1,HPV-6b L2 and one artificialHPV-16 mE7 proteins.Methods The artificial HPV-16 mE7 gene was designed by codon modification,point mutation and gene shuffling thenchemically synthesized and subcloned behind HPV-6b L2.HPV-6b L1 and L2-mE7 were expressed in insect cells byusing Bac-to-Bac system.The generated cVLPs were purified by CsCI gradient ultracentrifuge and analyzed byimmunoblot,electron microscope and haemagglutination assay.Results The HPV-6b L1 and L2-mE7 proteins were well expressed in insect cells and could selfassemble into cVLPs,whose diameter was about 55 nm and similar to that of HPV-6b L1/L2 VLPs.Intact cVLPs could be recognized byH6.M48 neutralizing monoclonal antibody and HPV-6b L2 polyclonal antibody,while the denatured cVLPs,but not theintact cVLPs,were reactive to HPV-16 E7 polyclonal antibody.HPV-6b L1/L2-mE7 cVLPs haemagglutinated mouseerythrocytes as efficiently as HPV-6b L1/L2 VLPs did.Conclusions The insertion of the 158 amino acid HPV-16 mE7 protein behind L2 did not disrupt the correct assemblingof cVLPs.The morphological characteristics and haemagglutinating activity of cVLPs were similar to those of HPV-6bL1/L2 VLPs.The cVLPs retained conformational B cell epitopes of HPV-6 VLPs and HPV-16 mE7 protein had an internallocation in the cVLPs.Therefore,large modified E7 protein with higher immunogenicity could be incorporated intocVLPs by fusing to the C-terminus of L2,which would help to improve the therapeutic effects of L1/L2-E7 cVLPs.
Background Human papillomaviruses (HPVs) can infect squamous or mucosal epithelia and cause cervical cancer or genital warts.Coinfection with multiple HPV types is a common finding of many epidemiological studies. Herefore it is necessary to to develop a vaccine, which can eradicate established HPV infections and prevent other HPV infections. Intuit study, we generated chimeric virus like particles (cVLPs) composed of HPV-6b L1, HPV-6b L2 and one artificial HPV-16 mE7 proteins. Methods The artificial HPV-16 mE7 gene was designed by codon modification, point mutation and gene shuffling thenchemically synthesized and subcloned behind HPV-6b L2. HPV-6b L1 and L2-mE7 were expressed in insect cells byusing Bac-to-Bac system.The purified cVLPs were purified by CsCI gradient ultracentrifuge and analyzed by immunoblot, electron microscope and haemagglutination assay. Results The HPV-6b L1 and L2-mE7 proteins were well expressed in insect cells and could selfassemble into cVLPs, whose diameter was about 55 nm and similar to that of HPV-6b L1 / L2 VLPs. Intact cVLPs could be recognized by H6.M48 neutralizing monoclonal antibody and HPV-6b L2 polyclonal antibody, while the denatured cVLPs, but not the inactivating cVLPs, were were to HPV-16 E7 polyclonal antibody . HPV-6b L1 / L2-mE7 cVLPs haemagglutinated mouseerythrocytes as efficiently as HPV-6b L1 / L2 VLPs did. Conlusions The insertion of the 158 amino acid HPV-16 mE7 protein behind L2 did not disrupt the correct assembling of cVLPs. The morphological characteristics and haemagglutinating activity of cVLPs were similar to those of HPV-6bL1 / L2 VLPs. The cVLPs retained conformational B cell epitopes of HPV-6 VLPs and HPV-16 mE7 protein had an internallocation in the cVLPs.Therefore, large modified E7 protein with higher immunogenicity could be incorporated intocVLPs by fusing to the C-terminus of L2, which would help to improve the therapeutic effects of L1 / L2-E7 cVLPs.