Cloning and characterisation of the Pasteurella multocida ahpA gene responsible for a haemolytic phenotype in Escherichia coli

Haemolysins are membrane-damaging agents which have been described as bacte rial virulence factors due to their ability to lyse erythrocytes and other host cells, and therefore inducing a greater inflammatory response (Elliott et al., 1998). Pasteurella multocida was found to be haemolytic under anae robic conditions. In this study, we cloned and characterised a P, multocida gene, designated ahpA, which conferred a haemolytic phenotype on Escherich ia coli when incubated under anaerobic conditions. A deletion was introduce d into the ahpA open reading frame which abolished the haemolytic phenotype , The clone containing ahpA showed erythrocyte specificity, causing haemoly sis of bovine and equine erythrocytes, and demonstrated weak haemolysis on ovine erythrocytes. Upon further investigation, AhpA was found to affect th e expression of the E. coli K-12 latent haemolysin, SheA, under anaerobic c onditions. (C) 2000 Elsevier Science B.V. All rights reserved.