الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Ten isolates of corynebacterium pseudotuberculosis were recovered from (100) a live sheep and (18) goats of which 14 Swabs were collected from swollen lymph node suspected to be CLA for the isolation of the causative agent using different methods of bacterial identification (culture, microscopical and biochemical characters). Out of 120 slaughtered sheep in the abattoir 20 enlarged lymph nodes were suspected to be CLA were collected. Nine samples out of the 20 enlarged lymph nodes were proved to be caused by corynebacterium pseudotuberculosis using different bacteriological methods. Serum samples were collected from 23 animal showing lesion suspected to be CLA (11 from alive sheep, 3 alive goats and 9 samples from slaughtered sheep) in addition to 55 serum samples from apparently healthy sheep and goats living in contact with the diseased ones (50sheep and 5 goats) and 10 serum samples from apparently healthy sheep (less than 3 months old) living in free area and this group act as a control negative. All samples were tested for the presence of PLD antibody by ELISA using PLD antigen as coating antigen Ten samples from alive and nine samples from slaughtered animals were positive with ELISA and also gave characteristic colony of C. pseudotuberculosis. All isolates were subjected to CAMP test and reverse CAMP test for confirmation of the hemolytic activity. All isolates were subjected to the amplification of PLD gene by PCR technique and proved positive in all isolates that have been positive with bacteriological identification. The virulences of all isolates were tested by guinea pigs S/C inoculation of a dose (1013) in the medial side of the thigh and examined for different pathogencity course induced by different isolates. Searching for the reason of the difference of the virulence of different isolates, the Elek’s test was done to all isolates for the investigation of the presence of the Diphtheria toxin but all isolates were negative for the Elek’s test. It is concluded that the difference in virulence of different isolates is due to differences in the expression of the PLD gene mainly in addition to other virulent genes and these virulent genes variability including PLD gene depend on many factors the most important of which is the bacterial-host interaction.