الفهرس 
Cover Page Title in EnglishOnly 14 pages are availabe for public view
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Abstract
Mastitis plays a prominent part among dairy ruminants . Resulting in most cases from infection of the mammary gland mastitis induce at least minor, but at most fetal illness to the affected animal causes major economic losses through reduction in milk yield and waste of milk un fit for consumption, massive antibiotic use and is a major cause of pre-mature culling . In sub-clinical mastitis the cow appears healthy, the udder doesn’t show any signs of inflammation and the milk seems normal, somatic cells that fight infections are found in elevated numbers in the milk . The cows that have sub-clinical mastitis are reservoirs of organisms and lead to infection to other cows . Most clinical cases start as sub-clinical . Controlling sub-clinical mastitis is the best way to reduce the clinical cases . Somatic cells are present in the milk through out lactation and consist of leukocyte and epithelial cells . Cytokines are one of the sensitive means in examining the immune responses of mammary glands and they could serve as a suitable tool for the udder health control or in evaluating of mastitis, treatment or vaccine efficiency . Understanding the regulation of the immune response during infections of the mammary gland is important for the design of prophylactic vaccines and for optimization of therapeutic protocols . The somatic cells are probably the main source of cytokines in milk . This study was carried out to investigate mastitis induce cytokine profiles at the level of transcriptional in milk somatic cells and the current investigation was designed to study the role of cytokines in immune response of clinical mastitis cattle . A total of 4 clinical S. aureus mastitis and 4 negative control sample. were used for the present study . The clinical samples were selected on the basis of clinical signs within 24 hours of the appearance of signs, California mastitis test and were selected on the basis of somatic cell count (SCC > 5 x 105) . Milk was centrifuged to collect somatic cell pellet by centrifugation at 1000 x g for 15 minutes and RNA was extracted from the pellet using R Neasy mini-kit (Qiagen-Germany) . Quality check and quantification of RNA was done The reverse transcription polymerase chain reaction (RT-PCR) amplification of IL-6, IL-8, IL-10 and IL-4 genes were carried out a long with B-Actin gene (Positive control) using primers . The reaction condition for each individual gene was optimized using a quantitect SYBR Green PCR kit (Qiagen-Germany) . All PCR reactions were performed in optical 96 well plates using applied Bio-system 7500 fast Real-Time PCR system (USA) . The amplification was varied out in a final reaction volume of 25 u . The PCR protocol designed for 40 cycles, fluorescence signals were measured once in each cycle at the end of the extension step for each gene of interest . For each sample a dissociation curve was generated after completion of amplification and analyzed to determine the specificity of PCR reaction . Values for target genes were normalized by the internal positive control determine the amplification of reference gene . The cytokine transcripts were calculated according to the comparative threshold cycle method (CT) . Data explained up regulation of all cytokines in all groups . The suppressive nature of S. aureus mastitis stimulated high level of IL-10 and IL-4 mRNA . These cytokines induced a shift in T-cell phenotype from CD4+ to CD8+ T-cell phenotypes . IL-8 is an important factor for activating neutrophils during inflammatory process, IL-8 up regulated in all groups . The activity of IL-6 induced by S. aureus mastitis . IL-6 up regulation markedly in S. aureus mastitis these due to S. aureus elicit immune response in cells dominantly by IL-6 .