A lytic bacteriophage vB_KpnP-6K2 inhibits ST11-KL64induced cell death and inflammatory response.

Abstract

INTRODUCTION: The global dissemination of multidrug-resistant() underscores the critical demand for alternative therapeutics such as bacteriophages. This study characterizes a novel bacteriophage, vB_KpnP-6K2 (6K2), isolated against a clinically relevant ST11-KL64strain, and evaluates its potential for therapeutic application. METHODS: Phage 6K2 was morphologically examined by transmission electron microscopy and genomically analyzed via whole-genome sequencing. Its stability across pH and temperature ranges, adsorption kinetics, and burst size were determined. The inflammatory response to Kpn infection was assessed in HEK293T, A549, Hela, and THP-1 monocytic cells by measuring cytokine and chemokine expression, while cell death was evaluated in A549 lung epithelial cells. The therapeutic efficacy of 6K2 was tested in a lethal murine systemic infection model, where a single intraperitoneal dose was administered one-hour post-bacterial challenge. Survival, bacterial clearance, and phage kinetics in blood were monitored. RESULTS: Phage 6K2 exhibits a polyhedral head and short tail, classifying it within the Podoviridae family (Autographiviridae family,genus). Its double-stranded DNA genome comprises 40,147 bp. The phage demonstrated stability across a broad pH (4-12) and temperature (4-50°C) range, rapid adsorption, and a burst size of 13.6 PFU/cell.,infection significantly upregulated inflammatory mediators in THP-1 cells and induced death in A549 cells; both responses were potently inhibited by 6K2 treatment. In the murine infection model, a single dose of 6K2 achieved 100% survival, accompanied by rapid clearance of bacteremia and high initial phage titers in the blood. DISCUSSION: These findings highlight the promising potential of bacteriophage 6K2 as an effective therapeutic agent against multidrug-resistantinfections. The phage not only suppresses bacterial load but also mitigates infection-associated inflammatory responses and cellular damage. The complete rescue in a lethal systemic infection model underscores it'sefficacy and supports further development of phage-based strategies for combating resistant bacterial infections.