الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 192 |  |  |
| | | from | 192 | | |
Abstract
SUMMARY AND CONCLUSION
Undoubtedly, necrotic enteritis is identified as one of the most threatening diseases which face poultry industry in Egypt and need radical solution to avoid huge economic losses. The present work was designed for typing Clostridium perfringens isolated from diseased chickens suspected to have necrotic enteritis from different outbreaks in six Governorates in Egypt (Gharbia, Dakhalia, Sharkia, Ismailia, North Sinai and Kafr El Sheikh) during the period from August to December 2018. Intestine and liver samples were obtained from eighty six diseased broiler chickens representing 60 flocks. C. perfringens was isolated and toxigenicity of the recovered isolates was determined by Nagler’s and dermonecrotic reactions. Furthermore, multiplex polymerase chain reaction (Multiplex PCR) targeting alpha, beta, epsilon and iota toxins’ genes was performed for result confirmation and typing of the toxigenic isolates. In addition, uniplex PCR was applied to detect the presence of NetB toxin. Sixty-six C.perfringens isolates (38.37%) were recovered from 172 intestine and liver samples, from which twenty isolates (30.3%) were toxigenic and typed as C. perfringens type A producing alpha toxin and only 3 out of 20 isolates (15%) were NetB-positive strains. These findings established the fact that alpha toxin is the only main toxin of C. perfringens type A which is basically responsible for its pathogenicity and virulence. In addition, most of the positively toxigenic isolates were isolated from hepatic lesions (15 isolates) rather than intestinal lesion (5 isolates).
Preparation of vaccine from one of the highly toxigenic isolated strains (63I) was occurred. The prepared toxoid was purified, separated and concentrated before its inactivation by formaline 0.5% for 5-7 days and adjvanted by aluminium hydroxide adsorbent gel 20%. Detection of MLD of toxin before its conversion to toxoid was applied and it was 1/80. Toxoid purity was evaluated by safety and sterility tests and it was found that the obtained toxoid was pure, sterile and safe to be administrated.