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Objective:To prepare a virus-like particle (VLP),containing Hepatitis B virus core antigen (HBcAg) and N-terminal peptides of the L2 protein of human papilloma virus (HPV),and investigate the immunogenicity of the VLP in mice and the protection against different strains of HPV .Methods:A fusion gene was synthesized to insert a DNA fragment ,coding for the N-terminal epitopes of the L2 protein of HPV16,into the HBcAg coding sequence;HBc-L2 fusion protein was highly expressed in E.coli using the pET9a and BL21(DE3) expression system;the purified fusion protein was used to immunize BALB/c mice and antibody titers against the L2 epitopes in mouse sera were determined by indirect ELISA;the levels of neutralizing antibodies against both HPV 16 and 18 were also analyzed.Results:HBc-L2 fusion protein was expressed in E.coli and purified,with the purity >80%,by ammonium sulfate pre-cipitation and CL-4B gel filtration;analysis of the purified fusion protein ,using size exclusion chromatography with multi-angle laser light scattering detection ( SEC-MALS) and electron microscope ,revealed that HBc-L2 was assembled into a stable VLP structure auto-matically following its expression;immunization of BALB/c mice with the purified VLPs resulted in high antibody titers in mouse sera against the L2 epitopes;furthermore,it was demonstrated that the sera from the immunized mice had neutralization activities against both HPV16 and HPV18.Conclusion:The immunogenicity of the L2 epitopes was highly enhanced by the construction of HBc-L2 fusion protein and the formation of the VLP structure;the fusion protein was also capable of inducing protections against different serotypes of HPV,therefore,it could be a potential HPV vaccine with a broad coverage and low production cost .
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Objective To detect the protection induced by HPV-58 L2 11-200 AA in animal, and analyze the relationship between antibody or neutralizing antibody titers and the protection generated by the immunizmg agent. Methods The peptide of HPV-58 L2 11-200 AA was expressed in E. coli and the mice were immunized with the peptide after purification and adsorption with aluminum adjuvant. The protection provided by different immunizing doses was detected in the mouse model against the challenge of the pseud-ovirions of human papiilomavirus types 58. The total antibodies and neutralizing antibody titers of serum were tested with ELISA and neutralization assay against HPV-58 pseudovirus, respectively. The total antibodies or neutralizing antibody titers that can protect the mouse from infection were analyzed. Results The mice can be protected from the challenge with HPV pseudovirus when the immunizing dose was 8 μg. The neutralizing antibody can not be detected in the immune serum by neutralization assay against pseudovirus. The total anti-body level has a corresponding relationship with the protection showed in mouse model. The results of total antibodies detected by ELISA showed that when the titer of total antibodies was ≥25 000, luminescent signal can not be detected and the mice can be protected from pseudovirus infection. Conclusion HPV-58 L2 11-200 AA peptide can protect mice from pseudovirus infection. L2 peptide has a promising perspective to be a candidate vaccine and the level of total antibodies in the immune serum can be used as a surrogate for the evaluation of protection against HPV infection.