Genes Involved in Haemophilus influenzae Type b Capsule Expression Are Frequently Amplified

The genes involved in Haemophilus influenzae type b capsule expression are present as a duplication of an ∼18-kb DNA segment (the Cap b locus). It has been shown previously that recombination occurs between the two copies of the repeat, resulting in deletion of one copy and loss of capsule expressio...

Full description

Saved in:
Bibliographic Details
Published in:The Journal of infectious diseases 1993-02, Vol.167 (2), p.356-364
Main Authors: Corn, Paul G., Anders, Joanna, Takala, Aino K., Kayhty, Helena, Hoiseth, Susan K.
Format: Article
Language:English
Subjects:
Antibodies
Bacterial Capsules - genetics
Bacterial Vaccines - analysis
Bacterial Vaccines - biosynthesis
Bacteriology
Biological and medical sciences
Blotting, Southern
District of Columbia
DNA
DNA probes
DNA, Bacterial - analysis
Enzyme-Linked Immunosorbent Assay
Enzymes
Finland
Fundamental and applied biological sciences. Psychology
Gels
Gene Amplification
Gene Expression Regulation, Bacterial
Genetic loci
Genetics
Haemophilus Infections - microbiology
Haemophilus influenzae
Haemophilus influenzae - genetics
Haemophilus influenzae - pathogenicity
Haemophilus influenzae type b
Haemophilus Vaccines
Humans
Major Articles
Microbiology
Nucleic Acid Hybridization
Polysaccharides
Polysaccharides, Bacterial - analysis
Polysaccharides, Bacterial - biosynthesis
Restriction Mapping
Virulence
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The genes involved in Haemophilus influenzae type b capsule expression are present as a duplication of an ∼18-kb DNA segment (the Cap b locus). It has been shown previously that recombination occurs between the two copies of the repeat, resulting in deletion of one copy and loss of capsule expression at frequencies of 0.1%–0.5%. The present study tested the hypothesis that the duplicated arrangement could serve as a template for further amplification of capsule gene sequences. Southern hybridization analysis of 66 type b invasive isolates showed that amplifications exist and are moderately common (23/66 were amplified). In addition to three copies of the 18-kb repeat, four copies were detected in some strains, and up to five copies in 1 isolate. By ELISA, a five-copy strain made about six times more capsular polysaccharide than did an isogenic two-copy derivative. The evolutionary significance of the duplicated arrangement may be its ability to rapidly amplify under conditions where it is advantageous to produce more capsule.
ISSN:0022-1899
1537-6613
DOI:10.1093/infdis/167.2.356