An oral inoculation infant rabbit model forShigellainfection

Abstract

250 words max) 18 Shigella species cause diarrheal disease globally. Shigellosis is typically characterized by 19 bloody stools and colitis with mucosal damage and is the leading bacterial cause of diarrheal 20 death worldwide. Following oral ingestion, the pathogen invades and replicates within the 21 colonic epithelium through mechanisms that rely on its type III secretion system (T3SS). 22 Currently, oral infection-based small animal models to study the pathogenesis of shigellosis are 23 lacking. Here, we found that oro-gastric inoculation of infant rabbits with S. flexneri resulted in 24 diarrhea and colonic pathology resembling that found in human shigellosis. Fasting animals 25 prior to S. flexneri inoculation increased the frequency of disease. The pathogen colonized the 26 colon, where both luminal and intraepithelial foci were observed. The intraepithelial foci likely 27 arise through S. flexneri spreading from cell-to-cell. Robust S. flexneri intestinal colonization, 28 invasion of the colonic epithelium, and epithelial sloughing all required the T3SS as well as IcsA, 29 a factor required for bacterial spreading and adhesion in vitro. Expression of the 30 proinflammatory chemokine IL-8, detected with in situ mRNA labeling, was higher in animals 31 infected with wild-type S. flexneri versus mutant strains deficient in icsA or T3SS, suggesting 32 that epithelial invasion promotes expression of this chemokine. Collectively, our findings 33 suggest that oral infection of infant rabbits offers a useful experimental model for studies of the 34 pathogenesis of shigellosis and for testing of new therapeutics. 35 42 dependent on the S. flexneri type III secretion system and IcsA, canonical Shigella virulence 43 factors. Thus, oral infection of infant rabbits offers a feasible model to study the pathogenesis 44 of shigellosis and to develop and test new therapeutics. 45 48 life-threatening (1). This enteric pathogen, which is spread by the fecal-oral route between 49 humans, does not have an animal reservoir or vector (1). Annually, Shigella infections cause 50 tens of millions of diarrhea cases and ~200,000 deaths (2, 3). It is likely the leading cause of 51 diarrheal mortality worldwide in individuals older than 5 years (2, 3). Most Shigella infections 52 are attributable to S. flexneri, one of the four Shigella species, although in developed nations 53the prevalence of S. sonnei is higher (4-7). 54 The pathogen primarily causes colonic pathology that usually includes mucosal 55 ulceration and erosion due to sloughing of epithelial cells, and is typically characterized by 56 acute inflammation, with recruitment of neutrophils and plasma cells, congestion of blood 57 vessels, distorted crypt architecture, and hemorrhage (8, 9). While inflammatory responses to 58 Shigella invasion of colonic epithelial cells were thought to be the underlying cause of epithelial 59 cell destruction and hemorrhage, recent evidence suggests that pathogen-mediated 60 destruction of epithelial cells also plays a role in...

Proteomic interrogation of the pathogen-host interface in cholera

“…6 Immunofluorescence Immunofluorescence images were analyzed from 6 rabbits infected with V. cholerae-GFP; or 6 sections of the small intestine per rabbit were examined. Briefly, tissue samples used for 6 immunofluorescence were fixed in 4% PFA for 2 hours, and subsequently stored in 30% sucrose prior to embedding in a 1:2.5 mixture of OCT (Tissue-Tek) and stored at -80°C, as previously 6described(75). Frozen sections were then cut at a thickness of 10catalog no.…”