ABSTRACT
The present study was carried out on the two local Sudanese Pasteurella multocida strain B and E which cause Hemorrhagic Septicemia (HS) disease in the Sudan and used for the production of the vaccine against this disease. This study was done to test the cross reaction between the two strains. The study showed that there was a cross reaction between the two strains in the rabbit sera when tested by ELISA. The active cross protection test in rabbits showed that vaccine of strain E protected 50% of the rabbits against challenge with strain B, while the vaccine of B could not protect the rabbits against the challenge with strain E 0%. Each vaccine of B and E could protect the rabbits 100% against the challenge with the same strain (homologously).