کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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2464485 | 1111798 | 2012 | 8 صفحه PDF | دانلود رایگان |
The objective of this study was to assess the role of leukotoxin (LKT) in modulating the pulmonary cytokine response of calves challenged with Mannheimia haemolytica. Thirty-six calves, seronegative to LKT and M. haemolytica whole cell antigen were divided into three groups (I, II and III). Calves in groups I and II were challenged by the intra-bronchial route with 25 mL of phosphate buffered saline (PBS) containing 0.44 × 109 cfu/mL of LKT deficient (lkt−) and 25 mL of PBS containing 0.31 × 109 cfu/mL of wild-type (wt) M. haemolytica serotype 1, respectively. Group III calves were challenged intra-bronchially with 25 mL of sterile PBS. Leukocytes were collected from broncho-alveolar lavage fluid (BALF) 4 days before and at 1, 3, and 6 days post-inoculation (p.i.). Expression of the following cytokines in the recovered leukocytes was measured using real-time PCR: interleukin (IL)-1β, -8, -10, -12 (p40) and TNF-α. The amount of TNF-α produced was also quantified by ELISA. Although a statistically significant difference in the expression of these cytokines was not observed between groups challenged with the wt and lkt− strains, the wt infected group (II) did exhibit higher mean clinical scores. Overall, there was considerable variation in the composition of the BALF between the groups and by day 7 p.i., both lkt−- and wt-challenged calves had seroconverted to M. haemolytica.
Journal: The Veterinary Journal - Volume 192, Issue 1, April 2012, Pages 112–119