A Novel Truncated CHAP Modular Endolysin, CHAP-161, That Lyses , , and , and Exhibits Therapeutic Effects in a Mouse Model of Infection.

Development of novel antibacterial agents is imperative due to the increasing threat of antibiotic-resistant pathogens. This study aimed to develop the enhanced antibacterial activity and in-vivo efficacy of a novel truncated endolysin, CHAP-161, derived from the endolysin LysSAP26, against multidrug-resistant bacteria. CHAP-161 exhibited higher protein purification efficiency in E. coli and antibacterial activity than LysSAP26. Moreover, CHAP-161 showed the higher lytic activity against with minimal bactericidal concentrations (MBCs) of 5-10 μg/ml, followed by with MBCs of 10-25 μg/ml. Interestingly, CHAP-161 could lyse anaerobic bacteria, such as , with MBCs of 25-50 μg/ml. At pH 4-8 and temperatures of 4°C-45°C, CHAP-161 maintained antibacterial activity without remarkable difference. The lytic activity of CHAP-161 was increased with Zn. In vivo tests demonstrated the therapeutic effects of CHAP-161 in murine systemic infection model. In conclusion, CHAP-161, a truncated endolysin that retains only the CHAP domain from LysSAP26, demonstrated enhanced protein purification efficiency and antibacterial activity compared to LysSAP26. It further displayed broad-spectrum antibacterial effects against , , and . Our in vitro and in-vivo results of CHAP-161 highlights its promise as an innovative therapeutic option against those bacteria with multiple antibiotic resistance.