Recombinant OmpX protein expression and its potential for serologically diagnosing abortion in mares.

Background And Aim: abortion in mares is caused by subspecies serovar infection and is characterized by premature (abortion) or non-viable fetus birth. Although all horses are susceptible to infection, the condition is more often clinically manifested in pregnant mares, with most abortions recorded in young females. In addition, nonspecific clinical disease signs and poorly sensitive and effective bacteriological diagnostic methods hinder rapid and reliable infection diagnoses. Immunochemical methods such as enzyme-linked immunosorbent assay (ELISA) and immunochromatography assays can facilitate effective and rapid diagnoses. However, they require highly specific and active antigens and antibodies. This study aimed to generate a recombinant outer membrane protein X (OmpX) and evaluate its suitability for serological diagnosis of abortion in mares

Materials And Methods: Outer membrane protein X from the antigen was synthesized and expressed in using the pET28 vector. Transformed cells were cultured under different conditions to detect recombinant OmpX (rOmpX) expression, and rOmpX purification and refolding were both conducted using metal affinity chromatography. Refolded and purified rOmpX was characterized by western blotting, liquid chromatography with tandem mass spectrometry, and ELISA.

Results: After optimized rOmpX expression, a 23 kDa molecular weight protein was identified. Amino acid sequence analysis using Mascot program suggested that these peptides were the OmpX protein from . High specificity and diagnostic efficiency were recorded when rOmpX was used in ELISA against 89 serum samples from aborted and contact mares.

Conclusion: Recombinant outer membrane protein, in comparison to the O antigen, demonstrated better diagnostic characteristics against sera from mares who aborted and contact horses.