Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 45 12 2016 12 27 1610 1617 Davoud AFSHAR Dept. of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Mohammad Reza POURMAND Dept. of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran AND Urology Research Center, Tehran University of Medical Sciences, Tehran, Iran Mahmood JEDDI-TEHRANI Monoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran Ali Akbar SABOOR YARAGHI Dept. of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Mohammad AZARSA Dept. of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Fazel SHOKRI Dept. of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran 2016 12 27 2016 12 27 Background: Choline-binding proteins (CBPs) are a group of surface-exposed proteins, which play crucial and physiological roles in Streptococcus pneumoniae. The novel member of CBPs, choline-binding protein M (CbpM) may have binding activity to plasma proteins. This study aimed to clone and express CbpM and demonstrate its interaction with plasma proteins and patients’ sera. Methods: The total length of cbpM gene was cloned in pET21a vector and expressed in BL21 expression host. Verification of recombinant protein was evaluated by Western blot using anti-His tag monoclonal antibody. Binding ability of the recombinant protein to plasma proteins and the interaction with patients’ sera were assessed by Western blot and ELISA methods. Results: The cbpM gene was successfully cloned into pET21a and expressed in BL21 host. Binding activity to fibronectin and fibrinogen and antibody reaction of CbpM to patients’ sera was demonstrated by Western blot and ELISA methods, respectively. Conclusion: CbpM is one of the pneumococcal surface-exposed proteins, which mediates pneumococcal binding to fibronectin and fibrinogen proteins.   https://ijph.tums.ac.ir/index.php/ijph/article/view/8636 https://ijph.tums.ac.ir/index.php/ijph/article/download/8636/5479