Cloning and sequencing of the gene encoding LipL21 in the vaccinal leptospira serovars

Leptospirosis is a zoonotic disease in humans and animals, caused by the bacterium Leptospira interrogans. Gene expressing LipL21 is one of the genes identified in the bacterium, existing only in the pathogenic strains. The aim of this study was to cloning and analyzing the sequence of the gene encoding surface lipoprotein, LipL21, in five vaccinal leptospira serovars in Iran. Pathogenic Leptospira interrogans serovars were cultured in EMJH medium with 10% rabbit serum. After genomic DNA extraction, PCR with specific primers was employed and the resulting product inserted in a vector then transferred into E. Coli DH5&alpha. The recombinant plasmids were finally sent for sequencing. The analysis of gene lipL21 in domestic vaccinal serovars and comparison of them with other serovars in the GenBank database revealed that three vaccinal serovars serjo hardjo, canicola and pomona had 100% similarity with each other and grippotyphosa serovar had the highest difference with the vaccinal serovars. In general, the results showed that this gene is a highly conserved gene in the domestic vaccinal serovars and serovars in the GenBank database with more than 95.7 percent similarity. These results showed that the gene, lipL21, is highly conserved in the vaccinal serovars (similarities > 96.4 %). Therefore, the gene encoding surface protein LipL21 can serve as a useful serologic test with high specificity and sensitivity for diagnosis of leptospirosis in clinical samples and in future as an effective subunit vaccine candidate to be used.