Recombinant multiepitope protein for diagnosis of leptospirosis

Leptospirosis is an emerging infectious disease and is considered to be the most widespread zoonotic disease in the world. It can be misdiagnosed because manifestations of this febrile disease vary from mild flu-like symptoms to severe illness involving vital organs such as the liver and lungs. Therefore, accurate diagnosis for differentiation of leptospirosis from other pyrogenic infections prevailing in the same locality is imperative for proper treatment. Here, we report a customized recombinant leptospirosis multiepitope protein (r-LMP) that can specifically detect the immunoglobulin class of anti-leptospirosis antibodies in patient sera. Immunodominant epitopes from leptospire outer membrane proteins OmpL1, LipL21, and LipL32 were predicted and confirmed using phage display and immunity reaction. On the basis of the sequences of the identified epitopes, five major immunodominant epitopes were selected to construct a synthetic gene, recombinant lmp. The recombinant lmp gene was doubled and expressed in Escherichia coli. The recombinant protein was purified and used as an antigen to develop an enzyme-linked immunosorbent assay for detection of special immunoglobulin M (IgM) or IgG in sera from patients with leptospirosis or other febrile illnesses and healthy subjects. The results showed that the r-LMP protein recognized IgG and IgM in all the sera that were microscope agglutination test positive, and there were no cross-reactions with other patient sera. This approach of creating customized antigens coupled to overexpression and simple purification offers a promising alternative option for leptospirosis diagnosis, with the potential to circumvent the drawbacks of whole-leptospirosis-antigen-based assays.