Binding of host iron-binding proteins and expression of iron-regulated membrane proteins by different serotypes of Pasteurella multocida causing haemorrhagic septicaemia.

Pasteurella multocida strains of serotype B: 2,5, B: 3,4 and E: 2,5 are associated with haemorrhagic septicaemia in domestic and feral ruminants. These strains were investigated for their ability to bind transferrin, lactoferrin and haemoglobin and for their ability to use these host iron-binding proteins as a source of iron. All strains bound haemoglobin, none of the strains bound lactoferrin, whereas transferrin binding was restricted to serotype B: 2,5 strains. Growth experiments indicated that transferrin (serotype B: 2,5) and haemoglobin could restore bacterial growth under iron-depleted conditions. Two distinct serotype-independent profiles of iron-regulated membrane proteins were expressed in vitro as well as in vivo.