الفهرس 
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Abstract
A total of 75 C. perfringens isolates was recovered from 200 examined lactating cattle collected from 17 dairy farms. Cases were selected according to history of decrease or no milk production accompanied diarrhea, edema and mastitis. from each animal rectal swab & milk samples were collected . C. perfringens was isolated from 20 milk samples, 47 rectal swabs while 4 isolate from milk and 4 isolate from rectal swabs were recovered from the same animal. The isolation of C. perfringens was carried out according to standard morphological and cultural characterization. All tested C. perfringens isolates were toxinotyped molecularly & idenitified as type A with an incidence of (100%) and negative for other types of examined toxins .The produced amplicon with alpha toxin primers was detected only at 324 bp. In the present work, the plc gene was amplified by new selected oligonucleotide primers. The amplified PCR product was 1106 bp for complete plc gene. The size of amplicons was determined by Totalab software analysis tool. The examined 8 isolates (4 milk and 4 feces from the same animals) were positive for plc gene.Two selected strains(milk and faeces were sequenced and accessed a GenBank No. KX524150 & KX524151.
The phylogenetic analysis of selected two strains and other reference strains on GenBank were applied by Megalign DNA star & MetaPIGA software analysis tools. The divergence percent of Egyptian strainsKX524151 (Bovine Feces) and KX524150 (Bovine Milk) is 32.4 & 1.5 % respectively. The other tested strains showed a similarity percent 100% either from Brazil, USA, Kazakhstan & China, except South Korean strains.The potential B-cell epitopes were predicted with their IEDB score (1.026) while,VaxiJen score (antigenicity) greater than 0.4. The epitopes from KX524150, HELQLGS, YLAYSIP and VTQGVSI have the highest antigenicity of 1.4219 , 1.4554 and 1.8007, respectively. In case of strain KX524151 the highest antigenic score was 1.6352 & 1.7089 for epitopes ; ANVTAVD and PILDVLL respectively.
So, this study aimed to identify the significant progress of mastitic cases caused by C. perfringens enterotoxogenic types with bacteriological & molecular methods. In addition to, introducing an Insilco new peptide vaccine design against enterotoxogenix C. perfringens depending on phospholipase C gene sequence using immunoinformatic analysis.