A Sensitive and Specific IgM-ELISA for the Serological Diagnosis of Human Leptospirosis Using a rLipL32/1-LipL21-OmpL1/2 Fusion Protein

摘要

Objective To construct a lipL32/1‐lipL21‐OmpL1/2 fusion gene and its prokaryotic expression system,and to establish an enzyme‐linked immunosorbent assay (ELISA) using the rLipL32/1‐LipL21‐OmpL1/2 fusion antigen of Leptospira interrogans for sensitive and specific detection of IgM in the serum of patients with leptospirosis.Methods lipL32/1‐lipL21‐OmpL1/2 fusion genes were constructed using a primer‐linking PCR.The target recombinant protein antigens,rLipL32/1,rLipL21,rOmpL1/2 and rLipL32/1‐LipL21‐OmpL1/2,were expressed and the purified antigens were then immobilized to the surface of microplate wells for ELISA‐based detection ofIgM in the sera of leptospirosis patients.Results Of 493 acute leptospirosis patients,95.7% and 97.8% were positive by rLipL32/1‐LipL21‐ OmpL1/2‐IgM‐ELISA using different serum dilutions,which was higher than the rLipL32/1‐IgM‐ELISA (93.1% and 90.3%),rLipL21‐IgM‐ELISA (90.3% and 87.0%),and rOmpL1‐IgM‐ELISA (85.6% and 81.1%) (P<0.01).All IgM‐ELISAs tested negative against 56 non‐leptospirosis patients with typhoid fever,hemorrhagic fever or dengue fever.Conclusion Trigeminal fusion antigen increases ELISA sensitivity and the rLipL32/1‐LipL21‐OmpL1/2‐ IgM‐ELISA is a sensitive and specific serological diagnostic method for clinical leptospirosis.