A highly synchronous murine model for EHEC infection reveals Shiga toxin promotes pathogen spread and systemic disease
Enterohemorrhagic Escherichia coli (EHEC) produces Shiga toxin, a phage-encoded toxin
that is essential for triggering life-threatening hemolytic uremic syndrome and renal
failure. How Stx targets the kidney and other extraintestinal tissues is poorly
understood. EHEC does not efficiently colonized conventional mice, but gavage of mice
with the related mouse pathogen, CR(stx), can ... read morecause a lethal systemic disease featuring
renal damage. We previously generated a food-borne route of infection for CR(stx) that
resulted in a highly synchronous disease model. This model allowed us to investigate the
pathogenesis associated with EHEC disease. We show here that CR(stx), but not purified
Stx, disrupts the intestinal barrier. The disruption in intestinal barrier function was
associated with the spread of CR(stx) to extraintestinal tissues, importantly the
kidney. Remarkably, the amount of Stx per CFU in kidney was 100-fold higher than that in
the colon. However, high levels of Stx in the kidney that could not be achieved when
CR(stx::kanR) inoculation was accompanied by a high dose of orally administered Stx.
These findings indicate that the intestinal epithelium is an important target of Stx,
resulting in the translocation of the pathogen to distant tissues. Further, the results
suggest that renal failure, a major manifestation of EHEC infection, results from high
levels of Stx produced by bacteria that have localized in the kidney after breakdown of
the intestinal barrier. Targeting the reservoir of EHEC would benefit the entire
populace because outbreaks are sporadic and seemingly unpredictable. Unfortunately, none
of the current vaccines for cattle provide complete protection from fecal shedding or
from colonization. Additionally, traditional methods of vaccination are not economically
feasible for cattle operations. Therefore, we test our food-borne mouse model as a proof
of principle model to investigate alternative vaccines. We show here that mice
pre-infected with wild-type CR are protected from a lethal challenge of CR(stx).
Additionally, we show that pre-infected mice produce a robust antibody response
following CR(stx) challenge. Ultimately, these findings demonstrate the utility of our
small animal model for testing alternative EHEC
Thesis (Ph.D.)--Tufts University, 2017.
Submitted to the Dept. of Molecular Microbiology.
Advisors: John Leong, and Joan Mecsas.
Committee: Cheleste Thorpe, Abraham Sonenshein, Ralph Isberg, and Cammie Lesser.
Keyword: Microbiology.read less