AUTHOR=Jiang Xi , Chu Chao , Wang Zhenyu , Gu Jiaojie , Hong Yaming , Li Qiuchun , Jiao Xinan 

TITLE=Preclinical evaluation of OMVs as potential vaccine candidates against Salmonella enterica serovar Enteritidis infection

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2022.1037607

DOI=10.3389/fcimb.2022.1037607

ISSN=2235-2988

ABSTRACT=<p><italic>Salmonella enterica</italic> serovar Enteritidis is the most prevalent serotype that causes human infections worldwide. Consumption of <italic>S.</italic> Enteritidis-contaminated animal foods is a major source of human infections; however, eradicating bacteria from animals remains difficult. Therefore, it is necessary to develop new measures to prevent and control salmonellosis. Here, we used the outer-membrane vesicles (OMVs) of <italic>S.</italic> Enteritidis and assessed their protective efficacy and immune response in mice. Deletion of <italic>tolR</italic> in <italic>S.</italic> Enteritidis increased the production and size of OMVs compared to those in the wild type (WT) and Δ<italic>rfaQ</italic> strains. Intramuscular immunization with OMVs conferred greater protection than intraperitoneal and intranasal immunization. Moreover, OMVs extracted from both WT and Δ<italic>tolR</italic> strains provided an 83.3% protective rate in mice challenged with <italic>S.</italic> Enteritidis, which was higher than that provided by OMVs extracted from the Δ<italic>rfaQ</italic> strain. However, compared with OMVs from the Δ<italic>tolR</italic> strain, OMVs from WT and Δ<italic>rfaQ</italic> strains rapidly eradicated <italic>S.</italic> Enteritidis colonizing the liver, spleen, ileum, and cecum of BALB/c mice after immunization. Immunization with OMVs from each of the three strains induced humoral immune responses and showed no side effects on the growth of mice. Our study revealed that OMVs from various <italic>S.</italic> Enteritidis strains could be developed for use as subunit vaccine candidates against nontyphoidal <italic>Salmonella</italic> infections in mammals.</p>