title: Genetics of spontaneous, high-frequency loss of b capsule expression in Haemophilus influenzae.
abstract: We determined that the frequency of spontaneous capsule loss in Haemophilus influenzae type b is 0.1 to 0.3%. All of 10 independent capsule-deficient variants (derived from four different type b strains) were found to be missing an identical 9-kilobase EcoRI restriction fragment when probed with a cloned piece of DNA containing sequences known to be necessary for type b capsule expression. These results suggest the existence of a specific mechanism for shutting off type b capsule synthesis at a high frequency. Intranasal infection of infant rats showed that capsule loss occurred in vivo at frequencies comparable to those observed in vitro.
authors.forename: S K
authors.initials: SK
authors.lastname: Hoiseth
authors.forename: C J
authors.initials: CJ
authors.lastname: Connelly
authors.forename: E R
authors.initials: ER
authors.lastname: Moxon
mesh_terms: D000942:Antigens, Bacterial / Q000235:genetics*; D002876:Chromosomes, Bacterial / Q000502:physiology; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D004269:DNA, Bacterial / Q000235:genetics* / Q000302:isolation & purification; D005798:Genes, Bacterial; D014644:Genetic Variation; D006193:Haemophilus influenzae / Q000235:genetics* / Q000472:pathogenicity; D008970:Molecular Weight; D009154:Mutation; D009693:Nucleic Acid Hybridization; D014169:Transformation, Bacterial; D014774:Virulence
chemical_list: D000942:Antigens, Bacterial; D004269:DNA, Bacterial; D004262:DNA Restriction Enzymes