A preliminary study on purification, identification and immunogenicity of HPV16 L1 VLPs

Objective To study a preliminary purification technique of human papillomavims 16 (HPVl6)L1 protein virus-like particles(VLPs) expressed in insect cell-baculovirus system and the immunogenicity of the purified VLPs in mice.Methods HPV16 L1 VLPs were purified by CsC1 and sucrose density gradient ultracentrifugation,and the purified VLPs were identified by Western blot,sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE)and electron microscopy.Six-week-old BALB/c mice were randomly divided into 6 groups,including 3 dose groups,2 adjuvant groups and a control group,and vaccinated with the purified VLPs 3 times at intervals of 2 weeks.Sera were taken and determined for anti-L1 antibodies by indirect ELISA.Results The purity of HPV16 L1 VLPs was up to 90% by SDS-PAGE identification.Intact VLPs were observed under the electron microscope.Anti-L1 antibodies were detected by ELISA in all dose groups and adjuvant groups.The titers of antibodies increased with vaccination times and dosage.Conclusion The HPV16 L1 VLPs expressed in insect cell-baculovirus system and purified by CsC1 and sucrose density gradient ultracentrifugation have immunogenicity and can induce strong humoral immune responses in mice. Key words: Human papillomavirus 16; L1 protein; Virus-like particles; Purification; Immunogenicity