Abstract 713: Monoclonal antibodies for the detection of the uropathogenic specific protein (USP): A bacterial genotoxin linked to colorectal cancer

Abstract

The Uropathogenic Specific Protein (USP) is an E. coli genotoxin nuclease primarily associated with urinary tract infections. Previous efforts in our laboratory found the USP gene in stool samples; more frequently found in stool samples from adenoma and CRC patients than in samples from healthy individuals. New efforts in our laboratory aim to find the USP protein in the same population of patient samples and this may require anti-USP antibodies, which at present are not commercially available. In this work, we report the first anti-USP monoclonal antibodies (mAbs) for the detection of USP in human samples. A total of 38 hybridoma supernatants containing mAbs were assayed by immunoblotting and biolayer light interferometry (BLI) for their ability to recognize purified USP(∆HNH). Results from BLI showed that the pair AB-A10 and AB-D5 presented the highest affinity with slow dissociation, moving forward for the development of a sandwich ELISA. Using AB-A10 as the capture antibody, and AB-D5 as the top antibody, results from the ELISA showed signals that were concentration-dependent above 6 ug/mL of USP. We also used the AB-D5 and AB-D10 in immunoblots for the detection of USP in proteins extracted from stool samples of patients with adenoma and CRC. The immunoblots reveal the detection of a 25 kDa protein that remains unidentified but is present only in some of the samples. This could be the first detection of USP protein directly in a biological sample. Efforts are underway to identify this protein band and confirm its identity as USP. Additional efforts are aimed at increasing the number of stool samples analyzed to establish whether USP protein is a risk factor for CRC or adenoma. Citation Format: Rachell Martínez-Ramírez, Valeria Toro-Díaz Toro-Díaz, Pearl Akamine, Kimberly Ruiz-Rosado, Ignacio Pino, Abel Baerga-Ortiz. Monoclonal antibodies for the detection of the uropathogenic specific protein (USP): A bacterial genotoxin linked to colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 713.