The Yersinia Phage X1 Administered Orally Efficiently Protects a Murine Chronic Enteritis Model Against Yersinia enterocolitica Infection

Abstract

<i>Yersinia enterocolitica</i> is generally considered an important food-borne pathogen worldwide, especially in the European Union. A lytic Yersinia phage X1 (Viruses; dsDNA viruses, no RNA stage; Caudovirales; and Myoviridae) was isolated. Phage X1 showed a broad host range and could effectively lyse 27/51 <i>Y. enterocolitica</i> strains covering various serotypes that cause yersiniosis in humans and animals (such as serotype O3 and serotype O8). The genome of this phage was sequenced and analyzed. No toxin, antibiotic-resistance or lysogeny related modules were found in the genome of phage X1. Studies of phage stability confirmed that X1 had a high tolerance toward a broad range of temperatures (4-60°C) and pH values (4-11) for 1 h. The ability to resist harsh acidic conditions and enzymatic degradation <i>in vitro</i> demonstrated that phage X1 is suitable for oral administration, and in particular, that this phage can pass the stomach barrier and efficiently reach the intestine <i>in vivo</i> without losing infectious ability. The potential of this phage against <i>Y. enterocolitica</i> infection <i>in vitro</i> was studied. In animal experiments, a single oral administration of phage X1 at 6 h post infection was sufficient to eliminate <i>Y. enterocolitica</i> in 33.3% of mice (15/45). In addition, the number of <i>Y. enterocolitica</i> strains in the mice was also dramatically reduced to approximately 10³ CFU/g after 18 h compared with 10⁷ CFU/g in the mice without phage treatment. Treatment with phage X1 showed significant improvement by intestinal histopathologic observations. Moreover, proinflammatory cytokine levels (IL-6, TNF-α, and IL-1β) were significantly reduced (<i>P</i> < 0.05). These results indicate that phage X1 is a promising candidate to control infection by <i>Y. enterocolitica in vivo</i>.