The Cytotoxic Necrotizing Factor of Yersinia pseudotuberculosis (CNFY) Enhances Inflammation and Yop Delivery during Infection by Activation of Rho GTPases

Abstract

Some isolates of Yersinia pseudotuberculosis produce the cytotoxic necrotizing factor (CNFY), but the functional consequences of this toxin for host-pathogen interactions during the infection are unknown. In the present study we show that CNFY has a strong influence on virulence. We demonstrate that the CNFY toxin is thermo-regulated and highly expressed in all colonized lymphatic tissues and organs of orally infected mice. Most strikingly, we found that a cnfY knock-out variant of a naturally toxin-expressing Y. pseudotuberculosis isolate is strongly impaired in its ability to disseminate into the mesenteric lymph nodes, liver and spleen, and has fully lost its lethality. The CNFY toxin contributes significantly to the induction of acute inflammatory responses and to the formation of necrotic areas in infected tissues. The analysis of the host immune response demonstrated that presence of CNFY leads to a strong reduction of professional phagocytes and natural killer cells in particular in the spleen, whereas loss of the toxin allows efficient tissue infiltration of these immune cells and rapid killing of the pathogen. Addition of purified CNFY triggers formation of actin-rich membrane ruffles and filopodia, which correlates with the activation of the Rho GTPases, RhoA, Rac1 and Cdc42. The analysis of type III effector delivery into epithelial and immune cells in vitro and during the course of the infection further demonstrated that CNFY enhances the Yop translocation process and supports a role for the toxin in the suppression of the antibacterial host response. In summary, we highlight the importance of CNFY for pathogenicity by showing that this toxin modulates inflammatory responses, protects the bacteria from attacks of innate immune effectors and enhances the severity of a Yersinia infection.

Temperature-responsive in vitro RNA structurome of Yersinia pseudotuberculosis

“…In addition to thermoregulated transcription, they are under RNAT control. The cytotoxic necrotizing factor CNFγ acts as toxin and is an essential virulence determinant, as it modulates inflammatory responses and counteracts attack by innate immune effectors (36,37). Similar to YadA, the adhesin AilA promotes binding to and subsequent killing of neutrophils via type III secretion-mediated translocation of effector proteins into the target host cell and promotes resistance against complement-mediated killing (38)(39)(40)(41).…”

Zinc acquisition via ZnuABC in Yersinia pseudotuberculosis facilitates resistance to oxidative stress

“…Mid-exponential phase Yptb strains were grown in YLB medium at 26°C, then washed twice in sterilized PBS and used for orogastric infection of 6-8-week-old female C57BL/6 mice using a ball-tipped feeding needle. For survival assays, 3 × 10 9 bacteria of each strain were applied to different groups of mice (n = 10/strain), and the survival rate of the mice was determined by monitoring the survival every day for 21 days (Heroven et al 2012;Schweer et al 2013). Survival times were analyzed using Kaplan-Meyer curves and comparisons were performed using the log-rank test.…”

Microbiome Populations in Lebanese Slaughterhouse Settings

“…This category also includes Staphylococcus aureus, Enterococcus species, Streptococcus species, Escherichia coli (including all three strain types, enterotoxigenic, enteropathogenic or enterohemorrhagic) and Yersinia pseudotuberculosis which we were able to isolate from muscle and facility surfaces in both locations. Campylobacter species and Yersinia enterocolitica are both associated with fecal contamination in water and food for animals and humans, originating in animal feces, and have been responsible for large food borne illness outbreaks previously that were traced to drinking water ingestion [35,52,53]. Yersinia pseudotuberculosis has also become a recognized human pathogen that is known to be distributed worldwide, but has not been well documented in the US or in Lebanon [52,53].…”

“…Campylobacter species and Yersinia enterocolitica are both associated with fecal contamination in water and food for animals and humans, originating in animal feces, and have been responsible for large food borne illness outbreaks previously that were traced to drinking water ingestion [35,52,53]. Yersinia pseudotuberculosis has also become a recognized human pathogen that is known to be distributed worldwide, but has not been well documented in the US or in Lebanon [52,53]. It is especially important as an emerging disease agent because some strains are able to elaborate a cytotoxic that can enhance disease pathogenicity in some people [53].…”

“…Yersinia pseudotuberculosis has also become a recognized human pathogen that is known to be distributed worldwide, but has not been well documented in the US or in Lebanon [52,53]. It is especially important as an emerging disease agent because some strains are able to elaborate a cytotoxic that can enhance disease pathogenicity in some people [53].…”