Characterization and immunogenicity of rLipL32/1-LipL21-OmpL1/2 fusion protein as a novel immunogen for a vaccine against leptospirosis
2015
Zhao, Xin (Zhejiang University School of Medicine, Zhejiang (China). Division of Basic Medical Microbiology, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, the First Affiliated Hospital) | Wang, Jiang (Zhejiang University School of Medicine, Zhejiang (China). Department of Medical Microbiology and Parasitology) | Ge, Yu-Mei (Zhejiang University School of Medicine, Zhejiang (China). Division of Basic Medical Microbiology, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, the First Affiliated Hospital) | Lin, Xu-Ai (Zhejiang University School of Medicine, Zhejiang (China). Division of Basic Medical Microbiology, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, the First Affiliated Hospital) | Yan, Jie (Zhejiang University School of Medicine, Zhejiang (China). Division of Basic Medical Microbiology, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, the First Affiliated Hospital) | Sun, Ai-Hua (Zhejiang Medical College, Zhejiang (China). Faculty of Basic Medicine)
Vaccination is an effective strategy to prevent leptospirosis, a global zoonotic disease caused by infection with pathogenic Leptospira species. However, the currently used multiple-valence vaccine, which is prepared with whole cells of several Leptospira serovars, has major side effects, while its cross-immunogenicity among different Leptospira serovars is weak. LipL32, LipL21 and OmpL1 have been confirmed as surface-exposed antigens in all pathogenic Leptospira strains, but their immunoprotective efficiency needs to be improved. In the present study, we generated a fusion gene lipL32/1- lipL21-ompL1/2 using primer-linking PCR and an engineered E. coli strain to express the recombinant fusion protein rLipL32/1-LipL21-OmpL1/2 (rLLO). Subsequently, the expression conditions were optimized using a central composite design that increased the fusion protein yield 2.7-fold. Western blot assays confirmed that rLLO was recognized by antirLipL32/ 1, anti-rLipL21, and anti-rOmpL1/2 sera as well as 98.5% of the sera from leptospirosis patients. The microscopic agglutination test (MAT) demonstrated that rLLO antiserum had a stronger ability to agglutinate the strains of different Leptospira serovars than the rLipL32/1, rLipL21, and rOmpL1/2 antisera. More importantly, tests in hamsters showed that rLLO provided higher immunoprotective rates (91.7%) than rLipL32/1, rLipL21 and rOmpL1/2 (50.0-75.0%). All the data indicate that rLLO, a recombinant fusion protein incorporating three antigens, has increased antigenicity and immunoprotective effects, and so can be used as a novel immunogen to develop a universal genetically engineered vaccine against leptospirosis.
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