The Evaluation of the Stability of Lipl41 Outer Membrane Protein Expression in Fusion with Lep, a Small Chaperone Protein, inLeptospira

Leptospirosis is a zoonotic disease caused by pathogenic spirochete called Leptospira that has worldwide distribution. Unfortunately, due to the variety of clinical symptoms, its diagnosis has many limitations. LipL41 is among the most abundant outer membrane proteins in Leptospira and is exclusively found in pathogenic species. A small gene called lep is located very close to lipl41 gene on the bacterial chromosome, which facilitates its expression. In this study, the expression and purification of LipL41-Lep fusion protein among prevalent pathogenic isolates in Iran was performed in a prokaryotic system for the first time.

All collected Lipl41 and Lep protein sequences were analyzed from the NCBI database. Complete codon sequences of the pattern of the Iranian serovars were designed and synthesized then sub-cloned into a pET32a+ and transformed into Escherichia coli BL21(DE3) to expression by using IPTG inducer. Thefusion recombinant protein was purified by denaturation and confirmed by western blot.

The results of PCR analysis showed a clear band of ~ 2000 bp in Agarose gel. Optimal expression of fusion recombinant protein (60kDa) was achieved post-induction at 4 h at 37 °C in the presence of 0.1 mM IPTG. Then it was purified in the insoluble form.

The results demonstrated that adequate amounts of this fusion recombinant protein were expressed andpurified to be used as a fusion antigen in serological testing, such as ELISA, or for the development of subunit vaccines against Leptospirosis in the future.