P. multocida contains one or more antigenic determinant of different proportions responsible for partial protection offered by the heterologous serovars. SDS-PAGE analysis of the whole protein profile prepared from sheep local isolates of P. multocida types (A, D), Mannheimia haemolytica type (A), P. trehalosi type (T) as well as standard strain of P. multocida (B6) revealed that the protein profile exhibited some differences with variable molecular masses ranged between 14 to 116 kDa. There are sharing protein subunits of molecular masses of 66, 37 and 28 kDa as the unique cross-reactive antigens in all isolates. The protection percentage for the vaccinated mice with inactivated M. haemolytica against the challenge with virulent strain of P. multocida type A, D and B6 are 30%, 30% and 20% respectively and 25%, 25% and 20% respectively in the groups of mice vaccinated with inactivated P. trehalosi so, there is cross reaction but limited cross protection between pasteurella isolates. The suggested vaccine must contain local isolates of P. multocida
serotypes A, D and B6 as well as M. haemolytica and P. trehalosi.