Phenotypic variation of carbohydrate surface antigens and the pathogenesis of Haemophilus influenzae infections.

Phenotypic variation of two major carbohydrate surface antigens of Haemophilus influenzae, the capsule and lipopolysaccharide, exemplifies some of the genetic mechanisms used by pathogenic bacteria in interacting with host microenvironments. The ability to generate phenotypic variety at high frequency within clonal populations of microorganisms provides an adaptive mechanism to combat the polymorphisms and immune repertoires of the host.