Immunological Studies On The Protective Antigens Of Pasteurella Multocida Of Avian Origin

Streptomycin dependent mutant strain of Past. multocida las obtaineti by using the N-me thyl-N-ni tro-N-ni trosoguanid1ne. Its colonial morphology,ability to grow at different temp- Iratures,growth requirements and time needed for visibleVawth,in addition to the similar properties of the virulentmd CU strains were recorded.Biochemical reactions of all Past. multocida strains awed completely the same behaviours except some variationsindole production and fermentation of lactose and mannitol.gave a clear cut differentation character of CU Subcutaneous injection of mutant strain did not produceclinical signs in mice when inoculated up to 108 micro- Virulenj strain killed mice even in a very small strain was less virulent to mice and high dosesneeded to cause death in mice.Virulent strain injected subcutaneously in chickens iUS8d 100% mortality when received 105 up to 108 viable.cteria,compared to 25%,50% and 75% of those receiving .102,103 and 104 viable cells respec ti vely. All birdssed to the mutant and CU strains were survived