Exogenous administration of lipids to steers alters aspects of the innate immune response to endotoxin challenge.

This study examined the effects of increasing energy availability from both dextrose and lipid treatments on the pro-inflammatory response to LPS in Holstein steers. Steers were randomly assigned to one of three groups: saline at 0.5 ml/kg body weight (Control) or 50% dextrose [0.5 ml/kg body weight (Dextrose) to mimic calm cattle's response to LPS] administered immediately prior to LPS (0.5 µg/kg body weight at 0 h) or continuous lipid emulsion infusion from -1 to 6 h [Intralipid 20% (Baxter, Deerfield, IL USA); 0.5 ml/kg/hr (Lipid) to mimic temperamental cattle]. Concentrations of non-esterified fatty acids (NEFA) were greater in Lipid compared with Control and Dextrose steers. A greater decrease in the change in rectal temperature, relative to baseline, was observed in response to LPS in Dextrose in comparison to control and Lipid steers. Cortisol was greater in Lipid than Dextrose and Control steers from -0.5 to 0 h, yet decreased from 0.5 to 5.5 h relative to LPS challenge. Concentrations of IL-6 were decreased in Lipid steers compared with Dextrose and Control steers, and were decreased in Dextrose compared with Control steers post-LPS challenge. These data suggest that increasing circulating NEFA using an exogenous Lipid emulsion may modulate the pro-inflammatory response in steers.

Proteomic analysis of cross protection provided between cold and osmotic stress in Listeria monocytogenes.

Listeria monocytogenes is a Gram-positive, foodborne pathogen responsible for approximately 28% of all food-related deaths each year in the United States. L. monocytogenes infections are linked to the consumption of minimally processed ready-to-eat (RTE) products such as cheese, deli meats, and cold-smoked finfish products. L. monocytogenes is resistant to stresses commonly encountered in the food-processing environment, including low pH, high salinity, oxygen content, and various temperatures. The purpose of this study was to determine if cells habituated at low temperatures would result in cross-protective effects against osmotic stress. We found that cells exposed to refrigerated temperatures prior to a mild salt stress treatment had increased survival in NaCl concentrations of 3%. Additionally, the longer the cells were pre-exposed to cold temperatures, the greater the increase in survival in 3% NaCl. A proteomics analysis was performed in triplicate in order to elucidate mechanisms involved in cold-stress induced cross protection against osmotic stress. Proteins involved in maintenance of the cell wall and cellular processes, such as penicillin binding proteins and osmolyte transporters, and processes involving amino acid metabolism, such as osmolyte synthesis, transport, and lipid biosynthesis, had the greatest increase in expression when cells were exposed to cold temperatures prior to salt. By gaining a better understanding of how this pathogen adapts physiologically to various environmental conditions, improvements can be made in detection and mitigation strategies.

Evaluation of endocrine and immune responses of steers challenged with infectious bovine rhinotracheitis virus.

OBJECTIVE: To evaluate the endocrine and immune responses of steers challenged with infectious bovine rhinotracheitis virus (IBRV). ANIMALS: 12 crossbred beef steers. PROCEDURES: Steers were randomly assigned to IBRV- (control) or IBRV+ treatment groups. Experimentally challenged steers (IBRV+) received a dose of IBRV intranasally (8.0 50% tissue culture infective doses), IBRV- steers received a saline (0.9% NaCl) solution placebo intranasally, and each group was placed in an isolated paddock. At 72 hours after challenge, all steers were fitted with indwelling jugular catheters and placed into individual stanchions. Blood samples were collected on days 4 through 8. Serum was analyzed for concentrations of cortisol, interleukin-6, interferon-γ, tumor necrosis factor-α, growth hormone, and insulin-like growth factor I. RESULTS: From 72 to 144 hours after challenge inoculation, the IBRV+ group had significantly greater mean rectal temperature, compared with the IBRV- group; the greatest temperatures in both groups were observed at 72 hours. Serum cortisol concentrations were increased in both groups from hours 72 to 136 and serum interferon-γ concentrations were greater in the IBRV+ from 94 to 112 hours after inoculation. Growth hormone concentration was greater in the IBRV+ group at various time points, but no difference in insulin-like growth factor- I concentration was observed. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that IBVR challenge altered growth hormone concentration at some time points but was not associated with large increases in circulating proinflammatory cytokines.

Use of bioluminescent Escherichia coli to determine retention during the life cycle of the housefly, Musca domestica (Diptera: Muscidae, L).

Researchers have documented that the housefly (Musca domestica) can serve as a vector for the spread of foodborne pathogens to livestock, food, and humans. Most studies have investigated Musca domestica as a vector only after the fly comes into contact or consumes the pathogen as an adult. The objective of this study was to determine whether the larvae of Musca domestica could ingest Escherichia coli from bovine manure and whether the E. coli could survive the metamorphosis process and be transmitted. Larvae (n=960) were incubated in sterilized bovine manure inoculated with 0, 3, 5, and 8 log10 colony-forming units (CFU)/mL of bioluminescent E. coli for 24 (larvae stage), 48 (larvae stage), 120 (pupae stage), and 192 h (adult stage). Larvae incubated for 24 h in bovine manure possessed 0.0, 2.7, 2.9, and 3.5 log(10) CFU/mL of E. coli, from inoculated with 0, 3, 5, and 8 log(10) CFU/mL of E. coli, respectively. Concentrations of E. coli within the pupae were 0.0, 1.7, 1.9, and 2.2 log(10) CFU/mL for each inoculation concentration, respectively. Flies that emerged from the pupae stage contained 0.0, 1.3, 2.2, and 1.7 log(10) CFU/mL of E. coli from larvae incubated in manure inoculated with concentrations of E. coli, respectively. These results suggest the housefly can emerge with quantities of E. coli. While this was an enteropathogenic E. coli (EPEC), these data may suggest that if the fly is capable of retaining similar concentrations of an enterohemorrhagic E. coli (EHEC), these concentrations may be capable of initiating illness in humans. Furthermore, the E. coli concentration within and on adult flies is related to environmental exposure. It must be noted that larvae were incubated in sterilized bovine manure, and there was no other bacterial competition for the E. coli. Thus, the rate of positive flies and concentrations present when flies emerged may vary under more realistic conditions.