Effect Of Experimental Infection Research Articles

Subclinical experimental infection with Taenia hydatigena in sheep is associated with production losses

The effect of experimental infection by Taenia hydatigena metacestodes on different productive parameters in sheep was evaluated. Seventeen male Columbia lambs distributed in three groups were used. The lambs of the first group (n = 5) were orally inoculated with 1000 T. hydatigena eggs (low dose). The lambs of the second group (n = 5) were inoculated orally with all the eggs of the last proglottid of an adult cestode (high dose). The lambs of the third group (n = 7) only received a placebo and were used as a control group. All lambs were humanely euthanized at week 13 postinfection, and carcass yield and conformation were evaluated.The infection rates of the lambs from the high-dose infected group and the low-dose infected group were 100% and 40%, respectively, with a mean of 2.4 ± 0.6 and 1 ± 0.7 metacestodes of T. hydatigena in the abdominal cavity, respectively. In a first multivariate study (MANOVA) considering the under the curve (AUC) values of body condition, weight gain, and feed consumption, as well as the final feed conversion values, showed a highly significant (p < 0.0001) group effect (high dose/low dose/uninfected). In a second multivariate study (MANOVA) considering the AUC values of eosinophils blood count, packed cell volume and alkaline phosphatase showed a highly significant (p < 0.0001) group effect (high dose/low dose/uninfected). The increase in serum ALP is a consequence of liver damage that had a strong negative correlation (r = −0.63, p < 0.007) with the body condition of the lambs. Despite these findings, we did not observe obvious clinical manifestations in any of the infected lambs. In general, no differences (p > 0.1) were observed between the lambs of the control group and the lambs of the low-dose infected group in the parameters evaluated.The results of this study show that the infection of T. hydatigena metacestodes subclinically produces a decrease in productive efficiency, alterations of some hematological and biochemical values, and a slight deterioration in the general appearance of the infected lambs. The above aspects are rarely detected by most farmers, but they have a negative impact on the productivity of infected lambs.

Evaluation of a Pasteurella multocida Respiratory Disease Induction Model for Goats (Capra aegagrus hircus).

Infectious respiratory diseases are a serious health concern worldwide. However, few models describe the experimental induction of lung infection, or the effect of experimental infection on clinical pathologic parameters in goats. Goats offer benefits compared to cattle because of size and tractability and compared to sheep with regard to specific features of their anatomy. In previous experimental models of infection in goats, coadministration of an immunosuppressive dose of a corticosteroid is common; however, protocols that use corticosteroid often note mortality as an adverse effect. We therefore investigated an infection protocol that did not use immunosuppression but instead relied on 2 intratracheal inoculations of Pasteurella multocida in healthy meat goats to induce clinical and hematologic changes associated with respiratory infection. Healthy Boer or Boer-Kiko cross goats (n = 6; age, 10 mo) were inoculated with Pasteurella multocida and were monitored over a 312-h period for clinical and hematologic parameters of infection. After induction of pneumonia, the goats had a significant 1.2 °C rise in rectal temperature and auscultatable rales for up to 96 h. Lymphocyte counts, serum amyloid A values, and respiratory scores were significantly different before and after induction of disease and were consistent with respiratory infection. No mortality was associated with this experimental infection, and minimal gross pathologic changes were noted at study termination. The clinical and pathologic findings of this study suggest a potentially reproducible method of establishing clinical respiratory infection in goats. The repeated intratracheal inoculation method of inducing caprine respiratory disease can be used to produce experimental respiratory disease in goats when the use of corticosteroid is not desirable. With the feasibility of this method established, additional research evaluating the optimal dose and frequency of P. multocida administration is needed.

Effects of E.coli O157:H7 Experimental Infections on Rabbits

The study aimed to show the effect of experimental infection with E.coli O157:H7 on some liver and kidney function in adult rabbits. Twenty five domestic rabbits (males and females), aged 6-8 weeks and weighing 1500-2000g, had a negative fecal bacteriological culture of E.coli O157:H7 were used. The rabbits were randomly divided into two groups: infected group (15 rabbits), each animal was drenched orally with 1ml of Phosphate buffer saline containing (2×109CFU) of E.coli O157:H7, while the control group (10 rabbits) were drenched orally (1ml) of Phosphate buffer saline, the clinical signs were daily observed for 30 days, recording of body weight and blood samples were collected at (0, 3, 15 and 30) days for serum to evaluate biochemical tests including Alanine transaminase, Aspartate aminotransaminase and alkaline phosphatase, creatinine, urea and total serum protein. The results showed different clinical signs after inoculation, including diarrhea, lethargy, weight loss, inability to eat or drink, urine was cloudy or milky, while control group remains in normal condition. The serum biochemical tests in infected group showed a significant increase of three enzymes at 15, and 30 days, the highest values of Alanine transaminase; Aspartate aminotransaminase and alkaline phosphatase showed at 30 days post infection as compared with the control group. Serum creatinine and urea recorded a significant increase (P&lt; 0.05) at 30 day post infection as compared with control group. However, total protein revealed a significant decrease in the infected group, and a significant decrease was noticed at 15 day post infection, while the control group showed an increase in total protein co-ordinated with increase of body weight and progressing age. This study concluded that the infection with E. coli O157:H7may cause changes in liver and kidney functions which were more sever at 15,30 days post infection.

Gastric stability and oral bioavailability of colistin sulfate in pigs challenged or not with Escherichia coli O149: F4 (K88)

The aim of the present study was to investigate the in vitro gastric stability of colistin sulfate (CS) and its antimicrobial activity against Escherichia coli and to study the impact of ETEC O149: F4 (K88) infection in pigs on CS intestinal absorption. The stability profile of CS was evaluated in a simulated gastric fluid (SGF). Antimicrobial activity of CS and its degradation products were examined in a 96-well polystyrene microplate model. The effect of experimental infection with ETEC O149: F4 on CS intestinal absorption was determined by quantification of CS systemic concentration using a validated LC–MS/MS method. A rapid degradation of CS accompanied by an increase in CS antimicrobial activity by comparison with non-degraded CS (P<0.0001) was observed in SGF. Additionally, CS levels were not quantifiable in systemic circulation using a highly sensitive method and concurrent oral challenge did not affect CS absorption in an induction model of subclinical post-weaning diarrhea (PWD).

Biochemical profile of Achatina fulica (Mollusca: Gastropoda) after infection by different parasitic loads of Angiostrongylus cantonensis (Nematoda, Metastrongylidae)

The effect of experimental infection by different parasitic loads of Angiostrongylus cantonensis (Nematode, Metastrongylidae) on the activities of the aminotransferases and concentration of total proteins, uric acid and urea in the hemolymph of Achatina fulica (Mollusca, Gastropoda) were investigated. There was a significant decrease in the concentration of total proteins in the exposed snails to 5000 or more larvae. This change was accompanied by an increase in the concentrations of urea and uric acid in the hemolymph, suggesting a higher rate of deamination of the amino acids. Besides this, variations in the activities of the aminotransferases were also observed, with the highest values recorded in the groups exposed to greater parasite load. These results suggest an increase in the use of total proteins, since there was increased formation of nitrogenous catabolites, in conformity with an increase in the aminotransferase activities. Infection was verified by the fact that L3 larvae recovered from the snails was proportion to the exposure dose of L1 larvae. Histopathological results also indicated presence of an inflammatory cell infiltrate, favoring an increase of both transaminases.

Trypanosoma evansi: Effect of experimental infection on the osmotic fragility, lipid peroxidation and calcium-ATPase activity of rat red blood cells

Trypanosoma evansi is the causative agent of equine trypanosomoses. The disease is characterized by fever, anemia, and cachexia. Peroxidative damage of the red blood cells caused by the parasite, may contribute to the pathogenesis of the anemia seen in trypanosomoses. Consequently, we evaluated the hematocrit, the osmotic fragility of the red blood cells, the level of lipid peroxidation and the activity of the Ca-ATPase of red blood cell ghosts from rats experimentally infected with T. evansi. After 72 h inoculation, the hematocrit decreased from 49.5% to 33%; the osmotic fragility of the red blood cells was approximately 40% higher as compared to the healthy animals; and the red blood cell ghosts showed a higher level of lipid peroxidation and a lower Ca-ATPase activity than the red cell ghosts from the healthy animals. In vitro incubations of red blood cells from healthy animals with T. evansi, produced also a significant increase of the osmotic fragility of the red blood cells.

Determination of Energy Response of Nuclear Track Detector Cellulose Nitrate CN-85 for Alpha Particles

Determination of Energy Response of Nuclear Track Detector Cellulose Nitrate CN-85 for Alpha Particles

Suppressed cytotoxic T lymphocyte responses in experimental cysticercosis

Mitogen-induced T cell responses are suppressed in mice infected with larvae of Taenia crassiceps. The effects of experimental infection on specific T cell responses, however, have not been examined. In the present study, we demonstrate that larval-infected mice exhibit suppressed ability to develop anti-virus specific cytotoxic T lymphocyte (CTL) responses while maintaining apparently normal natural killer (NK) cell responsiveness.

The effect of two challenge doses of Dictyocaulus filaria on the acquired immunity of sheep vaccinated with "Filiraq".

Twenty six lambs divided into four groups were used to study the effect of experimental infection with two challenge doses of D.filaria ( 100 &amp; 300 larvae / Kg. B. W.) on the aquired immunity after vaccination with irradiated larval vaccine “ Filiraq”. The clinical symptoms , eosinophi lic response, blood picture, faecal larval counts, gross pathological changes &amp; adult worm counts in the lungs were studied ... &#x0D; The results showed that a high dose of challenge (300 LI kg) prevents the development of expected acquired immunity, however the other vaccinated &amp; challenged group ( 100 LI Kg B.W ) showed good level of acquired immunity in comparison with other group.

Comparison Between Effects of Standard Feed and Whole Wheat Supplemented Diet on Experimental Eimeria tenella and Eimeria maxima Infections in Broiler Chickens

The effects of experimental infections with Eimeria tenella (Experiment 1, n = 144) or E. maxima (Experiment 2, n = 216) in broiler chickens fed whole wheat, with or without access to grit, as compared to a standard pelleted feed were studied. Inclusion of whole wheat was gradually increased up to 30% at 3 weeks of age. Grit was given separately. The chickens were kept on litter in a parasite-free environment with free access to water and feed. At 3 weeks of age half the number of chickens were individually inoculated with 500 sporulated oocysts of E. tenella (Experiment 1) or 3,000 sporulated oocysts of Eimeria maxima (Experiment 2), and the remaining birds were kept separate as uninfected controls. Neither coccidiostats nor growth enhancers were used. Oocyst concentration was determined from each group separately. Intestinal lesions were scored on 6 birds per feed regime 7 d postinoculation, and on the remaining birds at slaughter. Diet had no significant effect or bird performance during infection. However, there was an indication that the E. maxima infection had more negative effect on weight gain in birds given standard feed than in those given whole wheat supplement, but the difference was not significant (p < 0.09). The number of oocysts shed or mean intestinal lesion scores did not differ between diets in either experiment. In both experiments, the number of Clostridium perfringens was higher in the caeca of inoculated birds, but there were no differences between diets.

Effects of experimental infection with Eimeria bovis on the balance of sodium, potassium and water in calves

Balance trials were performed to investigate the effects of experimental Eimeria bovis coccidiosis on the metabolism of water, sodium and potassium in calves. Non-infected pair-fed controls and controls fed according to plan were included in the study to allow differentiation between the effects due to infection and due to changes in feed intake. Primary infection with 5 × 10 4 (group A) or 1 × 10 5 (group B) oocysts caused mild diarrhoea in three out of four group A calves and mild to severe haemorrhagic diarrhoea in all five group B calves. Losses of sodium and potassium via faeces tended to increase in the infected calves during patency and apparent digestibility ( AD) of these minerals was comparably low. In the urine of the infected calves the Na/K-ratio decreased due to a reduced urinary excretion of sodium. The retention ( RT) of sodium was particularly high in the calves that had received the higher oocyst dose. Potassium RT did not underlie significant changes during the course of coccidiosis. In the infected calves the plasma level of sodium was reduced transiently while the level of potassium remained fairly stable. Infections with the higher oocyst dose caused a distinct reduction of fluid excretion via urine which compensated for the increased faecal water losses during severe diarrhoea. Reinfection of the group A calves with 1 × 10 5 oocysts did not cause any significant metabolic impairment. The results of this study indicate that although acute sublethal bovine coccidiosis alters electrolyte and water metabolism the overall balance of electrolytes and water is largely maintained by physiologic adaptation.

Effect of experimental infection with [formula omitted] and scrotal insulation on leydig cell steroidogenesis in the ram

Testicular steroid content and Leydig cell steroidogenesis in vitro were investigated in rams on Days 28 and 58 after Trypanosoma congolense infection and were compared with those of rams in which testicular temperature had been raised artificially by insulation of the scrotum for 58 d. Testicular testosterone content increased significantly on Day 28 after infection but was lower than that of controls on Day 58 while it increased in scrotal-insulated rams compared with that of controls by Day 58. Testicular progesterone was undetectable in the control and trypanosome-infected groups throughout the experiment, but it increased in the insulated rams by day 58. Basal (unstimulated) Leydig cell testosterone production in the infected rams was similar to that of control rams on Day 28 but was significantly lower on Day 58. Stimulation of Leydig cell testosterone production with hCG or 22R-hydroxycholesterol (22ROHC) significantly reduced in infected rams at both 28 and 58 d after infection as well as in scrotal-insulated rams on Day 58. It is concluded that the increase in testicular testosterone content in the infected and scrotal-insulated rams on Days 28 and 58, respectively, was induced by elevation of testicular temperature by trypanosome infection, perhaps through an effect on testicular blood flow. Reduced testosterone production by Leydig cells from infected and scrotal-insulated rams in response to hCG and 22ROHC suggests that trypanosome-induced pyrexia might be involved in reducing Leydig cell steroidogenesis and subsequent plasma testosterone levels, possibly by affecting enzymes involved in steroid biosynthesis.

Effects of experimental infection with Leptospira interrogans serovar balcanica on the health of brushtail possums (Trichosurus vulpecula)

Data on changes in the condition and feeding behaviour of captive brushtail possums (Trichosurus vulpecula) following an experimental infection with Leptospira interrogans serovar balcanica are presented. The daily food intake of nine experimentally infected possums was recorded for 47 days before and 24 days after balcanica inoculation (0.5 ml intraperitoneally containing about 108 organisms). Body weight was recorded seven times between 42 days before and 96 days after inoculation. The mean daily food intake of infected possums decreased significantly throughout the 24-day recording period after infection with balcanica. The mean body weight of infected possums had decreased significantly by day 26 after inoculation but had fully recovered by day 96 after inoculation. Uninfected and control possums showed no significant changes in mean daily food intake or mean body weight over the experimental period. These data suggest that the health of possums is temporarily affected by infection with balcanica, but that overt disease caused by balcanica is unlikely. These findings support previous research suggesting that balcanica has only subclinical effects on possums.

Effect of experimental infection with Listeria monocytogenes on the development of pregnancy and on concentrations of progesterone, oestrone sulphate and 15-ketodihydro-PGF2 alpha in the goat.

The effect of Listeria monocytogenes infection on hormone levels in pregnant goats was studied. Four goats (Group I) received an intravenous inoculation of a bacterial culture (Type 1) on Days 69-77 and another four goats (Group II) received a similar inoculation on Days 105-106 of gestation. Five non-inoculated goats were used as controls. Plasma was analysed for progesterone, oestrone sulphate and 15-ketodihydro-PGF2 alpha. The status of the foetus was followed using real-time ultrasonography. Three of the four goats in Group I aborted 8-10 days after inoculation. The fourth goat gave birth to a normal live kid at term. The three goats which aborted showed clinical signs of disease in connection with abortion. In Group II, all goats aborted after 9-11 days. All the goats showed clinical symptoms of disease from a few days after inoculation and the symptoms continued until abortion. The clinical symptoms of disease were more pronounced in Group II than in Group I. L. monocytogenes was isolated from all aborted foetuses. None of the control goats aborted. Ultrasound examination revealed foetal death either immediately before or up to 2 days before abortion. Mummification had begun in the foetus that had been dead for 2 days before expulsion. In comparison with pre-inoculation plasma levels in Group I, a significant decrease (P < 0.05) in progesterone levels and an increase in 15-ketodihydro-PGF2 alpha levels were observed from Days 4 and 6 after inoculation, respectively. In Group II, a significant decrease (P < 0.05) in progesterone levels and an increase in 15-ketodihydro-PGF2 alpha levels in plasma were observed from Days 8 and 6, respectively. The oestrone sulphate levels decreased slightly in the inoculated goats a few days before abortion. The pattern of changes in levels around abortion was similar to the pattern present in the control animals around parturition. However, oestrone sulphate levels did not increase in the inoculated groups before abortion in contrast to goats which delivered healthy kids. The changes in levels of 15-ketodihydro-PGF2 alpha in goats that aborted indicated that the endocrine foetal-placental function was disturbed, which was most likely due to the establishment and development of L. monocytogenes in the placenta and foetus.

Effect of experimental infection with stomach worm (Haemonshus contortus) on the productive performance of does

Effect of experimental infection with stomach worm (Haemonshus contortus) on the productive performance of does

Effect of Experimental Infection with Pasteurella haemolytica on Pulmonary Function in Feedlot Calves

The purpose of this study was to evaluate the effect of experimentally-induced pneumonia due to Pasteurella haemolytica on pulmonary function in feedlot calves.

Effects of experimental infection with Border disease virus on lymphocyte subpopulations in the peripheral blood of lambs

Experimental infection with Border disease virus was characterised by significant changes in the total numbers of leucocytes and neutrophils, and in the proportions and numbers of the different lymphocyte subpopulations. Three days after experimental infection there was significant leucopenia due to lymphocytopenia and neutropenia (P<0·001). The lymphocytopenia and neutropenia lasted for up to seven days after inoculation. The lymphocytopenia was due to a reduction in the number of both T cells and B cells. During the early period of infection, the reduction in T cells was mainly due to a reduction in the number of OvCD4+ and T-19+ lymphocytes as the number of circulating OvCD8+ cells was not significantly affected. The cells expressing the OvCD4 and OvWC1 epitopes returned to pre-inoculation values 10 and 14 days after inoculation, respectively. In contrast, during the same period, the number of T cells expressing the OvCD8 molecule became significantly higher than the corresponding pre-inoculation values. There were no significant changes in all the T cell subsets in the control lambs.

The effect of experimental infection with Corynebacterium pseudotuberculosis on reproduction in adult ewes

Fifteen ewes were inoculated subcutaneously with 2 × 10 6 cells of Corynebacterium pseudotuberculosis seven days before mating, during the embryonic stage of gestation and during the fetal stage of gestation. The clinical signs, antibody response and the consequences of the infection on reproduction were studied. None of the ewes showed any change in general condition during pregnancy. The effects of experimental infection during gestation were evident after incubation periods that ranged from 25 to 140 days after inoculation and were dependent on the time of the inoculation in relation to the period of gestation. Ewes inoculated before gestation can resolve infection. Ewes inoculated during the embryonic stage were severely affected and some aborted. In others lambs were stillborn or, if born alive, infected. Ewes inoculated during the fetal stage of gestation did not show reproductive disorders although some remained chronically infected.

The effect of experimental infection with Rhodococcus equi on immunodeficient mice

To investigation the pathogenesis of respiratory lesions caused by the facultative intracellular pathogen, Rhodococcus equi, pulmonary clearance was compared in four groups of genetically defined mice, chosen for their specifi deficits in immune and inflammatory responses. Complement-deficient A/J, immunodeficient nu/nu (nude), scid/scid.bg/bg (SCUD/beige), C57BI/6J.bg/bg (beige) and normal Swiss mice (SW) received approximately 10 7 R. equi intranasally on day 0. Bacterial clearance was assessed in lung, liver and spleen on days 1, 4, 7 and 14. Pulmonary clearance was not significantly different between SW and A/J mice. Beige mice cleared R. equi more rapidly and completely than A/J and SW, indicating that deficits in phagocytic and NK cell function associated with the bg/bg gene did not compromise clearance. Pulmonary clearance in immunodeficient SCID/beige mice paralleled that of the SW and A/J mice initially but bacterial proliferation produced significant differences from SW mice at day 14. Nude were unable to clear R. equi from day 1, resulting in th death of two nude mice at day 11. Both SCID/beige and nude mice developed severe pyrogranulomatous bronchopneumonia, whereas A/J and SW mice developed transient pulmonary lesions. Beige mice developed minimal lung lesions. Significant systematic bacterial proliferation occurred only in nude and SCID/beige mice. We conclude that deficiencies in complement components, phagocytic and NK cells do not impair the pulmonary clearance of R. equi but that a competent cellular immune system is required to prevent pneumonia and death. The difference in early phase pulmonary clearance in nude and SCID/beige mice indicates two phases are important for clearance. An acapsular mutant of R. equi was completely cleared from the lungs of SCID/beige mice suggesting an important role for the capsule in virulence for mice.

Studies on new dehydropeptidase inhibitors. III. Biological properties of WS1358A1.

WS1358A1, a novel inhibitor of renal dehydropeptidase (DHP), augmented the urinary recovery of a carbapenem antibiotic imipenem and improved its protective effect in experimental infections when simultaneously administered to mice with the antibiotic. WS1358A1 was a competitive DHP inhibitor with a Ki value of 1.6 x 10(-7) M.