Virulence Determination for Rapid Extraintestinal Dissemination (Acute Infection) of Common Salmonella Serotypes in Swine

Salmonella enterica (Typhimurium and Choleraesuis) have been shown to rapidly disseminate extraintestinally (RED) within 3 hours of intranasal inoculation in pigs (1,2,5,6). Evaluation of RED serotypes may be an important indicator of Salmonella virulence. Experimentally, pigs were challenged with important lymph node, fecal, and vaccine isolates of Salmonella and evaluated for RED. These isolates include S. Heidelberg, S. Infantis, S. Derby, S. Worthington, S. 4, 12 imonophasic, S. untypable HL 10416, S. Typhimurium, S. Typhimurium variant Copenhagen, S. Bredeney, S. Muenchen, S. Brandenburg, S. Choleraesuis SC-38, S. Choleraesuis SC-54, and S. Choleraesuis strain Argus. Three hours after intranasal inoculation, the pigs were euthanized, necropsied, and the following tissues were collected for qualitative isolation: tonsil, thymus, blood, mandibular lymph node, lung, spleen, liver, ileocecal lymph node, colon contents, and cecum contents. Fewer tissues were positive for vaccine strains compared with wild type or parent strains

Virulence determination for rapid extraintestinal Dissemination (Acute Infection) of Common Salmonella Serotypes in Swine

Salmonella enterica (Typhimurium and Choleraesuis) have been shown to rapidly disseminate extraintestinally (RED) within 3 hours of intranasal inoculation in pigs (Fedorka-Cray et al., 1995) (Blaha et al., 1997) (Nugent et al., 2000) (Nielsen, 2000). Evaluation of RED serotypes may be an important indicator of Salmonella virulence. Experimentally, pigs were challenged with important lymph node, fecal and vaccine isolates ofSalmonella and evaluated for RED. These isolates include: Salmonella Heidelberg, Salmonella Infantis, Salmonella Derby, Salmonella Worthington, Salmonella 4, 12 i-monophasic, Salmonella untypable HL I 0416, Salmonella Typhimurium, Salmonella Typhimurium variant Copenhagen, Salmonella Bredeney, Salmonella Muenchen, Salmonella Brandenburg, Salmonella Choleraesuis SC-38, Salmonella Choleraesuis SC-54, and Salmonella Choleraesuis strain Argus. Three hours after intranasal inoculation, the pigs were euthanized, necropsied, and the following tissues were collected for qualitative isolation: tonsil, thymus, blood, mandibular lymph node, lung, spleen, liver, ileocecal lymph node, colon contents and cecum contents. Fewer tissues were positive for vaccine strains as compared to wild type or parent strains

Distinct Peripheral Blood RNA Responses to Salmonella in Pigs Differing in Salmonella Shedding Levels: Intersection of IFNG, TLR and miRNA Pathways

Transcriptomic analysis of the response to bacterial pathogens has been reported for several species, yet few studies have investigated the transcriptional differences in whole blood in subjects that differ in their disease response phenotypes. Salmonella species infect many vertebrate species, and pigs colonized with Salmonella enterica serovar Typhimurium (ST) are usually asymptomatic, making detection of these Salmonella-carrier pigs difficult. The variable fecal shedding of Salmonella is an important cause of foodborne illness and zoonotic disease. To investigate gene pathways and biomarkers associated with the variance in Salmonella shedding following experimental inoculation, we initiated the first analysis of the whole blood transcriptional response induced by Salmonella. A population of pigs (n = 40) was inoculated with ST and peripheral blood and fecal Salmonella counts were collected between 2 and 20 days post-inoculation (dpi). Two groups of pigs with either low shedding (LS) or persistent shedding (PS) phenotypes were identified. Global transcriptional changes in response to ST inoculation were identified by Affymetrix Genechip® analysis of peripheral blood RNA at day 0 and 2 dpi. ST inoculation triggered substantial gene expression changes in the pigs and there was differential expression of many genes between LS and PS pigs. Analysis of the differential profiles of gene expression within and between PS and LS phenotypic classes identified distinct regulatory pathways mediated by IFN-γ, TNF, NF-κB, or one of several miRNAs. We confirmed the activation of two regulatory factors, SPI1 and CEBPB, and demonstrated that expression of miR-155 was decreased specifically in the PS animals. These data provide insight into specific pathways associated with extremes in Salmonella fecal shedding that can be targeted for further exploration on why some animals develop a carrier state. This knowledge can also be used to develop rational manipulations of genetics, pharmaceuticals, nutrition or husbandry methods to decrease Salmonella colonization, shedding and spread

Dose Determination for Acute Salmonella Infection in Pigs

Pigs were exposed to various levels of Salmonella enterica subsp. enterica serovar Typhimurium by either intranasal inoculation or by subjecting them to a contaminated environment. More than 10(3) salmonellae were required to induce acute Salmonella infection. These results indicate that intervention against acute Salmonella infection in lairage may be more readily achieved than previously thought

Equine hydrallantois is associated with impaired angiogenesis in the placenta

Introduction: Hydrallantois is the excessive accumulation of fluid in the allantoic cavities during the last trimester of pregnancy, leading to abdominal wall hernias, cardiovascular shock, abortion, and dystocia. It has been postulated that hydrallantois is associated with structural and/or functional changes in the chorioallantoic membrane. In the present study, we hypothesized that angiogenesis is impaired in the hydrallantoic placenta. Method: Capillary density in the hydrallantoic placenta was evaluated in the chorioallantois via immunohistochemistry for Von Willebrand Factor. Moreover, the expression of angiogenic genes was compared between equine hydrallantois and age-matched, normal placentas. Results: In the hydrallantoic samples, edema was the main pathological finding. The capillary density was significantly lower in the hydrallantoic samples than in normal placentas. The reduction in the number of vessels was associated with abnormal expression of a subset of angiogenic and hypoxia-associated genes including VEGF, VEGFR1, VEGFR2, ANGPT1, eNOS and HIF1A. We believe that the capillary density and the abnormal expression of angiogenic genes leads to tissue hypoxia (high expression of HIF1A) and edema. Finally, we identified a lower expression of genes associated with steroidogenic enzyme (CYP19A1) and estrogen receptor signaling (ESR2) in the hydrallantoic placenta. Discussion: Based on the presented data, we believe that formation of edema is due to disrupted vascular development (low number of capillaries) and hypoxia in the hydrallantoic placenta. The edema leads to further hypoxia and consequently, causes an increase in vessel permeability which leads to a gradual increase in interstitial fluid accumulation, resulting in an insufficient transplacental exchange rate and accumulation of fluid in the allantoic cavity

Paternally expressed retrotransposon Gag-like 1 gene, RTL1, is one of the crucial elements for placental angiogenesis in horses

RTL1 (retrotransposon Gag-like 1) is an essential gene in the development of the human and murine placenta. Several fetal and placental abnormalities such as intrauterine growth restriction (IUGR) and hydrops conditions have been associated with altered expression of this gene. However, the function of RTL1 has not been identified. RTL1 is located on a highly conserved region in eutherian mammals. Therefore, the genetic and molecular analysis in horses could hold important implications for other species, including humans. Here, we demonstrated that RTL1 is paternally expressed and is localized within the endothelial cells of the equine (Equus caballus) chorioallantois. We developed an equine placental microvasculature primary cell culture and demonstrated that RTL1 knockdown leads to loss of the sprouting ability of these endothelial cells. We further demonstrated an association between abnormal expression of RTL1 and development of hydrallantois. Our data suggest that RTL1 may be essential for placental angiogenesis, and its abnormal expression can lead to placental insufficiency. This placental insufficiency could be the reason for IUGR and hydrops conditions reported in other species, including humans