Antibody-based detection of the bacterial nuclease toxin uropathogenic specific protein (USP)

Abstract The uropathogenic specific protein (USP) is a bacterial nuclease associated with urinary tract infections and genotoxicity. Although the usp gene has been detected in human samples, the detection of the encoded protein has proved elusive. Here, we report an antibody-based test to detect the USP protein in biological samples. Using biolayer interferometry, we evaluated 38 mouse hybridomas containing USP-specific antibodies. The resulting purified antibodies (mAb-A10 and mAb-D5) are the first monoclonals that specifically recognize USP. They were used to develop a single-antibody enzyme-linked immunosorbent assay (ELISA) using a 0.1 to 0.12.5 µg/ml range with a lower limit of quantification (LOQ) of 0.13 µg/ml, and a lower limit of detection (LOD) of 0.04 µg/ml. The method was implemented for the detection of USP in human urine samples. Two urine samples registered a statistically significant response by ELISA, although the protein levels were found to be below the LOQ. This method, and the antibodies reported herein, will greatly facilitate the study and detection of USP in clinical samples. Key points Bacterial usp gene had been implicated in several human diseases.We report the first test for the detection of bacterial USP protein.This is the first report of monoclonal antibodies against USP protein.