CLONING OF THE HAEMOCIN LOCUS OF HAEMOPHILUS-INFLUENZAE TYPE-B AND ASSESSMENT OF THE ROLE OF HAEMOCIN IN VIRULENCE

The bacteriocin haemocin (HMC) is produced by most type b strains of H aemophilus influenzae, including strains determined to be genetically diverse, and is toxic to virtually all non-type b strains of H, influe nzae. both encapsulated and non-encapsulated. Examination of the deduc ed amino acid sequences of several genes upstream of the previously id entified HMC immunity gene (hmcI) revealed several features common to class II bacteriocins of certain Gram-positive bacteria. Mutagenesis o f the open reading frame immediately upstream of hmcI resulted in a lo ss of the HMC production phenotype, When an HMC-producing strain of H. influenzae and the HMC-deficient isogenic mutant were compared for in vasion in the infant-rat model, the HMC-producing strain was found to invade significantly earlier; however, a significantly higher number o f rats infected with the isogenic mutant became bacteraemic as compare d with those infected with the HMC-producing parent.