Therapeutic Efficacy of Phage PSAE-01E2 against Abortion Caused by Salmonella enterica Serovar Abortusequi in Mice.

Abstract

subsp.serovar Abortusequi is a frequently reported pathogen causing abortion in mares. In this study, the preventive and therapeutic effects of phage PSAE-01E2 againstAbortusequi in a mouse model of abortion were investigated. Phage PSAE-01E2 was stable at different temperatures (4 to 70&#xb0;C) and pH values (pH 4 to 10) and could lyse the majority of theserogroup O:4 and O:9 strains tested (25/28). There was no lysogeny-related, toxin, or antibiotic resistance-related gene in the genome of PSAE-01E2. All of these characteristics indicate that PSAE-01E2 has the potential for use in phage therapy. Inexperiments, 2&#x2009;&#xd7;&#x2009;10CFU/mouse ofAbortusequi ATCC 9842 was sufficient to lead to murine abortion (gestational day 14.5) within 48 h. A single intraperitoneal inoculation of PSAE-01E2 (10PFU/mouse, multiplicity of infection = 10) 1 h before or afterAbortusequi challenge provided effective protection to all pregnant mice (10/10). After 24 h of treatment with phage PSAE-01E2, the bacterial loads in both the placenta and the uterus of the infected mice were significantly decreased (<10&#x2009;CFU/g) compared to those in the placenta and the uterus of the mice in the control group (>10&#x2009;CFU/g). In addition, the levels of inflammatory cytokines in the placenta and blood of the mice in the phage administration groups were significantly reduced (0.05) compared to those in the placenta and blood of the mice in the control group. Altogether, these findings indicate that PSAE-01E2 shows the potential to block abortions induced byAbortusequiAbortusequi is an important pathogen that can induce abortions in mares. AlthoughAbortusequi has been well controlled in Europe and the United States due to strict breeding and health policies, it is still widespread in African and Asian countries and has proven difficult to control. In China, abortions caused byAbortusequi have also been reported in donkeys. So far, there is no commercial vaccine. Thus, exploiting alternative efficient and safe strategies to controlAbortusequi infection is essential. In this study, a new lytic phage, PSAE-01E2, infectingAbortusequi was isolated, and the characteristics of PSAE-01E2 indicated that it has the potential for use in phage therapy. A single intraperitoneal inoculation of PSAE-01E2 before or afterAbortusequi challenge provided effective protection to all pregnant mice. Thus, PSAE-01E2 showed the potential to block abortions induced byAbortusequi.