AUTHOR=Coloma-Rivero Roberto F. , Gómez Leonardo , Alvarez Francisco , Saitz Waleska , del Canto Felipe , Céspedes Sandra , Vidal Roberto , Oñate Angel A. 

TITLE=The Role of the Flagellar Protein FlgJ in the Virulence of Brucella abortus

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=10

YEAR=2020

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2020.00178

DOI=10.3389/fcimb.2020.00178

ISSN=2235-2988

ABSTRACT=<p><italic>Brucella abortus</italic> is a facultative intracellular pathogen that causes a zoonosis called brucellosis. This disease leads to abortion and infertility in cattle, and diverse complications in humans. <italic>B. abortus</italic> is a successful intracellular bacterium that has developed the ability to evade the host's immune system and it replicates in professional and non-professional phagocytic cells, persisting in the different tissues, and organs of its hosts. It has been described that <italic>Brucella</italic> expresses a polar flagellum under certain conditions, but its function is still unknown. In this study we evaluated the role of the FlgJ, a protein, presumably a peptidoglycan hydrolase involved in flagellum formation and in the virulence of <italic>B. abortus</italic> strain 2308. <italic>B. abortus</italic> 2308 Δ<italic>flgJ</italic> mutant and complemented strains were constructed to study the function of the FlgJ protein in the context of the virulence of this pathogen in <italic>in vitro</italic> and <italic>in vivo</italic> assays. The results showed that the elimination of the <italic>flgJ</italic> gene delays the growth rate of <italic>B. abortus</italic> in culture, reduces its intracellular survival capacity in professional and non-professional phagocytic cells, rendering it unable to escape from the endocytic route and not reaching the endoplasmic reticulum. It also negatively affects their persistence in BALB/c mice. Functionally, the <italic>B. abortus</italic> 2308 <italic>flgJ</italic> gene restored motility to an <italic>E. coli flgJ</italic> mutant gene. Furthermore, it was discovered that the production of FlgJ protein is associated with the bacterial adherence by <italic>B. abortus</italic>. Therefore, although the specific function of the polar flagellum for <italic>Brucella</italic> is unknown, the data indicates that the flagellar <italic>flgJ</italic> gene and its product are required for full virulence of <italic>B. abortus</italic> 2308, since its deletion significantly reduces the fitness of this pathogen <italic>in vitro</italic> and <italic>in vivo</italic>.</p>