Immunological studies on pasteurella haemolytica in sheep

ABSTRACT

In the period from January-July 2001 respiratory manifestations appeared on 53 out of 239 sheep at Sakha station of reproduction Research center, causing death of 30 cases. Clinically history symptoms and necropsy findings were reported. Pasteurella haemolytica was incriminated as the causative agent of this problem. This organism was isolated from nasal swabs of clinically diseased sheep and from pharyngonasal swabs, lung tissue of six emergency slaughtered cases. The isolates were identified biochemically and serologically and using pathogenicity test. Two antigens leukotoxin and whole cell associated with Pasteurella haemolytica. SDS-PAGE of leukotoxin yield four protein bands ranged from 80 KDa to 98 Kda while whole cell antigen yielded 10 protein bands ranged between 22 to 85 KDa. Antigens associated with P. haemolytica whole cell and leukotoxin were identified for their immunogenic activity by neutralization test and ELISA. The neutralizing antibodies against leukotoxin in sheep were significantly higher than antibodies against the whole cell antigen. Also, antibodies titre to leukotoxin by ELISA were significantly higher than antibody titre to whole cell antigen, Pathological examination revealed that the sacrified sheep suffered from pneumonia with various lesions in lymph nodes, liver, kidney, heart and brain