Study On Species Established And Quality Of Recombinant Trivalent Human Papillomavirus Vaccine

Human Papillomavirus(HPV),a non-enveloped,double-stranded DNA virus,is the necessary cause of cervical cancers and other cancer.Infections by HPV genotypes 16,18,and 58 are implicated in approximately 70%of cervical cancer,thus the production of a vaccine against HPV16/18/58 has important practical significance in the prevention of cervical cancer in China and Southeast Asia.In this study,we screened bacterial strains expressing the protein of interest,and assessed the quality of these bacterial strains in various aspects.The results are as follows:(1)the recombinant plasmids expressing soluble HPV L1 proteins were transformed into four E.coli host cells,namely BL21(DE3),BL21,Origami2(DE3),and XA90.By means of preliminary and thorough screenings for single clones,tests and analysis,we identified XA90 as the strain that showed higher expression levels of the L1 proteins of HPV 16,18,and 58 compared with those of the other three strains examined;(2)optimized the culture condition for XA90:induction temperature is 30 ?,induction time is 6 h,and the concentration of the inducer(lactose)is 2g·L-1;(3)the original seed lots were prepared from shaking-flask cultures,and the master seeds and working seeds were prepared subsequently by sub-cultivation.Test items and quality standards for seed lots were formulated based on Chinese Pharmacopoeia,according to which thorough quality tests were performed on HPV16,18,and 58 seed lots.The results suggested that the quality control indicators were in line with the requirements;(4)plasmid stability and expression level of protein of interest were tested on cells produced by continuous sub-cultivation.The results suggested that after 25 passages from the original seed lots,the cells still had good genetic stability and effectiveness of the vaccine.This study has laid a solid foundation for the large-scale production of HPV trivalent vaccines.