Cloning of chromosomal DNA from Haemophilus influenzae. Its use for studying the expression of type b capsule and virulence.

摘要: Haemophilus influenzae may make any one of six chemically distinct capsular polysaccharides, but only strains serotype b commonly cause systemic infection (e.g., meningitis) in humans. Molecular cloning DNA was used to investigate the expression type capsule and its association with H. virulence. A virulent strain construct a lambda library chromosomal Charon 4. Two independently isolated recombinant phage were from found possess necessary for capsule. Using well-characterized rat model infection, we showed that transformants elicited by cloned pathogenic, causing bacteremia meningitis, whereas untransformed capsule-deficient organisms not. 4.4-kb EcoRI fragment, common both clones, characterize clinical isolates representing all encapsulated serotypes as well several Southern hybridization analysis. The probe hybridized an identical sized (4.4 kb) fragment EcoRI-digested eight strains. Single bands homology also fragments obtained 33 encapsulated, nontype influenzae. However, size these proved be characteristic each different serotypes. These studies provide basis pursuing molecular analysis epidemiology virulence pathogenic