BackgroundSalmonella is a highly successful parasite of reptiles, birds and mammals. Its ability to infect and colonise such a broad range of hosts coincided with the introduction of new genetic determinants, among them 5 major pathogenicity islands (SPI1-5), into the Salmonella genome. However, only limited information is available on how each of these pathogenicity islands influences the ability of Salmonella to infect chickens. In this study, we therefore constructed Salmonella Enteritidis mutants with each SPI deleted separately, with single individual SPIs (i.e. with the remaining four deleted) and a mutant with all 5 SPIs deleted, and assessed their virulence in one-day-old chickens, together with the innate immune response of this host.ResultsThe mutant lacking all 5 major SPIs was still capable of colonising the caecum while colonisation of the liver and spleen was dependent on the presence of both SPI-1 and SPI-2. In contrast, the absence of SPI-3, SPI-4 or SPI-5 individually did not influence virulence of S. Enteritidis for chickens, but collectively they contributed to the colonisation of the spleen. Proinflammatory signalling and heterophil infiltration was dependent on intact SPI-1 only and not on other SPIs.ConclusionsSPI-1 and SPI-2 are the two most important pathogenicity islands of Salmonella Enteritidis required for the colonisation of systemic sites in chickens.
ABSTRACT:The purpose of the present study was to assess the effect of kaolin feeding on health status, body weight gain (BWG), course of diarrhoeal infections caused by enterotoxigenic strains of Escherichia coli (ETEC) and the level of mycobacterial contamination in weaned piglets. The testing was performed in two experiments involving 40 weaned piglets at the age of 28 days. In the infection-free experiment, piglets were fed a diet without (C0) or with 1% content of kaolin (K0) for 20 days. Subsequently, all of them were fed the same diet without kaolin supplementation for 39 days. Identical diets were fed during the infection experiment, and moreover, both groups (CI and KI) were orally infected with ETEC (O141:F18ac, STa+) on Day 1 of experiment. The short-term feeding of kaolin to weaned piglets had a significant positive effect on their BWG. During the period of feeding the kaolin-containing diets, BWG in C0 and K0 were 0.20 and 0.29 kg, respectively (P < 0.05), and in CI and KI 0.13 and 0.19 kg, respectively (P < 0.05). There was no evidence of side effects to their health, neither was there any change in biochemical and haematological profiles. In the infection experiment, a protective effect of kaolin on the course of ETEC infection was evident. Colonization and shedding of ETEC by piglets fed the kaolin diet were milder and had a shorter duration in comparison with control piglets. The culture examination of pure kaolin and kaolin containing diets for mycobacteria were negative. Potentially pathogenic mycobacteria occurring in the environment were isolated from faeces and tissues of pigs. According to these results, supplementation of diets with 1% kaolin to prevent diarrhoea in piglets and to support their growth in the critical post-weaning period could be recommended.
The aim of the present investigation was to determine the influence of increased intake of fats (calciferous salts of fatty acids) in the early lactation period on the development of liver steatosis. Twenty dairy cows in the study were divided into an experimental group (E; n = 10) and a control group (C; n = 10). Balanced diets of energy content, crude protein and minerals (except calcium) were fed to the two groups of dairy cows. The differences were in the fat content (3.7% and 6.99% dietary dry matter in the control and experimental groups, respectively), fibre (14.4% and 15.6% dietary dry matter in the control and experimental groups, respectively) and calcium (0.83% and 1.3% dietary dry matter in the control and experimental groups, respectively). The source of fats in the diet fed to the experimental group was treated rape cake (calciferous salts of fatty acids). The two diets were introduced on the day of calving. Blood samples were collected in weeks 2 and 4 post partum, and liver biopsies were performed in week 4 post partum.The histological examination of liver samples showed a significantly higher lipid infiltration (69.03 ± 8.42 vs. 23.83 ± 5.16%; p < 0.01) and significantly lower liver glycogen concentrations (25.74 ± 2.74% vs. 53.15 ± 1.74%; p < 0.01). Two weeks post partum, the experimental group had significantly higher blood serum concentrations of betahydroxybutyrate -BHB (1.04 ± 0.58 vs. 0.54 ± 0.18 mmol·l -1 ; p < 0.05), non-esterified fatty acids -NEFA (0.96 ± 0.57 vs. 0.39 ± 0.24 mmol·l -1 ; p < 0.05), total cholesterol (3.54 ± 1.29 vs. 2.51 ± 0.44 mmol·l -1 ; p < 0.05), total bilirubin (8.61 ± 3.73 vs. 5.29 ± 1.07 µmol·l -1 ; p < 0.05), lactate dehydrogenase -LDH (49.79 ± 12.43 vs. 37.20 ± 5.48 µkat·l -1 ; p < 0.05), significantly lower concentrations of total protein (78.77 ± 5.01 vs. 88.72 ± 7.05 g·l -1 ; p < 0.01) and urea (4.09 ± 0.92 vs. 4.99 ± 0.61 mmol·l -1 ; p < 0.05). In week 4 post partum, the experimental group had significantly higher concentrations of NEFA (0.62 ± 0.48 vs. 0.25 ± 0.1 mmol·l -1 ; p < 0.05), total cholesterol (4.70 ± 0.77 vs. 3.03 ± 0.49 mmol·l -1 ; p < 0.01), LDH (45.97 ± 10.70 vs. 36.14 ± 3.97 µkat·l -1 ; p < 0.05) and significantly lower concentration of urea (4.43 ± 1.01 vs. 5.88 ± 1.08 mmol·l -1 ; p < 0.01).Our investigations suggest that increased intake of fats (6.99% dietary dry matter) in the early lactation period has a substantial effect on the development of liver steatosis. Fatty liver, liver biopsy, blood, glycogen, triacylglycerolIn recent years, the production efficiency of dairy cows has constantly been increasing, which has led to higher demands on the supply of their nutrients. The most difficult problems have been encountered in the early lactation period when dairy cows have a negative energy balance. The main problem of that period is the limited intake capacity for dry matter, as a consequence of which dairy cows are unable to cover their energy needs from feeds. In an effort to obtain the energy necessary for milk production, the cows us...
Encephalitozoon cuniculi is an obligate intracellular pathogen that has a wide host distribution, but primarily affects rabbits. The aim of this study was to characterize both the cell-mediated and the antibody response in rabbits after experimental infection using 2 different infection routes: oral and ocular. SPF rabbits were infected with low (10³ spores) and high (10⁷ spores) infection doses. Monitored parameters included clinical signs, detection of spores in urine, antibody response detected with ELISA, and cell-mediated immunity detected by antigen-driven lymphocyte proliferation. At week 13 post-infection, half of the rabbits in each group were suppressed by intramuscular administration of dexamethasone. At week 18 post-infection, animals were euthanized. Clinical signs were mild with exacerbation after immunosuppression. Spores in urine and antigen-specific cell-mediated immunity were detected from weeks 5 and 4 post-infection, respectively. Specific IgM was detected 1 week after infection, and IgG antibodies followed 1 week later in rabbits infected with the high dose. Immunological responses were dose dependent. The authors can conclude that both oral and ocular experimental infection with E. cuniculi resulted in an immune response of the infected animals. Rabbits could be used as an experimental model for the study of ocular microsporidiosis.
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