Isolation, Identification, and Prophylactic Evaluation of a Newly Isolated C. perfringens Phage

Clostridium perfringens is a major livestock pathogen responsible for histotoxic diseases and intestinal infections, posing serious threats to public health and the poultry and breeding industry. Overreliance on antibiotics has driven the emergence of drug-resistant strains and disruption of gut microbiota homeostasis, underscoring the urgent need for alternative control strategies. In this study, a lytic phage designated vB_CppII_Hohhot was isolated from wastewater samples collected from large-scale dairy farms in Inner Mongolia. The optimal multiplicity of infection was determined to be 0.1. pH stability was assessed. The phage was found to remain stable across pH 3 to 11, but no viable phage was detected at pH 12 (detection limit: <1 PFU/mL). Temperature adaptability was also assessed. Peak titers were achieved between 37°C and 40°C, and the titer was observed to fall below the detection limit at temperatures above 45°C. At a constant temperature of 37 °C, the phage rapidly reached the plateau phase within 40 min, with bacterial counts significantly reduced by 14 h. Whole-genome sequencing revealed that the phage genome consisted of 76 open reading frames, with no detectable antibiotic resistance or virulence genes; an endolysin gene potentially responsible for its lytic activity was also identified. In a prophylactic mouse model, phage administration significantly reduced pathological damage. Collectively, these findings provide a newly isolated candidate agent and a theoretical basis for the prophylactic application of phages against C. perfringens-associated infections.