Cloning,Expression and Immunogenicity of S-layer Membrane Protein Gene(Lslp) of Pathogenic Leptospira interrogans
致病钩体表层膜蛋白新基因（Lslp）的克隆表达及免疫原性研究

S layer proteins was assumed to play crucial role in the virulence of pathogens.In order to elucidate of role of Leptospira interrogans S layer protein, the encoding gene was cloned and expressed in E.coli . The immunogenecity of the recombinant protein was assayed. The primer for PCR amplification was based on previous data (GenBank AF325807), genomic DNA from 6 strains of Leptospira interrogans were used as template for amplification separately. The resulting PCR fragments of Lslp genes from 6 different pathogenic strains were sequenced and aligned. Lslp gene of Leptospira interrogans serovar Lai was subjected to further studies. The recombinant plasmid pGST Lslp was constructed and used to transfer the host E.coli JM109 The recombinant fusion protein was purified and used to immunize the rabbit. The antibody titers was determined by ELISA with Lslp immunized rabbit serum. The results showed the new S layer protein gene was highly conserved in 6 strains of pathogenic Leptospira interrogans . The sequence homology was 99 6%. The gene was not detected in nonpathogenic Leptospira. The apparent molecular weight of the expressed GST fusion protein was 66 kD. Western blot demonstrated a clear band reacted with rabbit anti pan Leptospira serum. The maximum antibody titers of Lslp immunized reaction reached 1:5120 These data indicate that the surface layer protein (Lslp) of Leptospira interrogans can be recognized by host and its role in the host pathogen interaction needs further investigation. The study provide clue for further explaining the molecular mechanism of pathogenic Leptospira and screening the target for the vaccine design.