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Open Access Research article

Characterization of Conserved Combined T and B Cell Epitopes in Leptospira interrogans Major Outer Membrane Proteins OmpL1 and LipL41

Xu'ai Lin1, Aihua Sun13, Ping Ruan14, Zhe Zhang1 and Jie Yan12*

Author Affiliations

1 Department of Medical Microbiology and Parasitology, School of Medicine, Zhejiang University, 388 Yuhangtang Road, Hangzhou 310058, PR China

2 Basic Medical Microbiology Division, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, School of Medicine, Zhejiang University, Hangzhou 310058, PR China

3 Faculty of Basic Medicine, Zhejiang Medical College, Hangzhou 310053, PR China

4 Department of Medical Microbiology and Parasitology, Medical School of Shaoxing University, Shaoxing 312000, PR China

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BMC Microbiology 2011, 11:21  doi:10.1186/1471-2180-11-21

Published: 26 January 2011

Abstract

Background

Leptospira interrogans are bacterial pathogens of animal that cause zoonotic infections in human. Outer membrane proteins of leptospire are among the most effective antigens which can stimulate remarkable immune responses during the infection processes, and thus are currently considered leading candidate vaccine antigens. The objective of the present study is to predict and confirm major combined B and T cell epitopes of leptospiral outer membrane proteins OmpL1 and LipL41, as well as to evaluate their capacity in the induction of immune responses in BALB/c mice.

Results

In this study, four epitopes from OmpL1 and four from LipL41 conserved regions were evaluated for their potential utilization in leptospire vaccines. Firstly, combined B and T cell epitopes were predicted by softwares and expressed using a phage display system. OmpL1 residues 87-98 and 173-191 (OmpL187-98 and OmpL1173-191) and LipL4130-48, LipL41233-256 of LipL41 were identified as immunodominant B cell epitopes by Western blot. Epitopes OmpL1173-191, OmpL1297-320 of OmpL1 and LipL41233-256, LipL41263-282 of LipL41 were identified as immunodominant CD4+ T cell epitopes through proliferation analysis of splenocytes from recombinant OmpL1 (rOmpL1) or recombinant LipL41 (rLipL41)-immunized BALB/c (H-2d) mice. These epitopes induced responses of CD4+ T cells and Th1 (T helper cells) type cytokine responses during the infection.

Conclusion

This work identified combined T and B cell immunodominant epitopes in outer membrane proteins OmpL1 and LipL41 of Leptospira interrogans. OmpL1173-191 of OmpL1 and LipL41233-256 of LipL41 could be useful in a vaccine against Leptospira. The findings could also contribute to the development of effective cross-protective vaccine strategies for leptospirosis.