Serotype and genus specific protein antigens of Pasteurella multocida, revealed by monoclonal antibodies

Two monoclonal antibodies (mAbs) reacting with protein antigens of Pasteurella multocida strain M1404 were produced and designated DM-1 and DM-4. DM-1 reacted only with the homologous Heddleston serotype 2. On the other hand, DM-4 reacted with all the 16 Heddleston serotypes and with other Pasteurella spp., but not with any of the other genera tested. Both mAbs may thus be of significance for identification and classification. The antibodies could agglutinate P. multocida only if the cells were treated with 1N HCl. Neither of the mAbs could opsonise P. multocida for phagocytosis by mouse macrophages nor did they protect recipient mice against lethal infection. Active immunisation of mice gave rise to only partial protection against challenge infection, suggesting a minor role for these particular proteins in protection from infection.