Comparative genomic profiling of Dutch clinical Bordetella pertussis isolates using DNA microarrays: identification of genes absent from epidemic strains.
BACKGROUND
Whooping cough caused by Bordetella pertussis in humans, is re-emerging in many countries despite vaccination. Several studies have shown that significant shifts have occurred in the B. pertussis population resulting in antigenic divergence between vaccine strains and circulating strains and suggesting pathogen adaptation. In the Netherlands, the resurgence of pertussis is associated with the rise of B. pertussis strains with an altered promoter region for pertussis toxin (ptxP3).


RESULTS
We used Multi-Locus Sequence Typing (MLST), Multiple-Locus Variable Number of Tandem Repeat Analysis (MLVA) and microarray-based comparative genomic hybridization (CGH) to characterize the ptxP3 strains associated with the Dutch epidemic. For CGH analysis, we developed an oligonucleotide (70-mers) microarray consisting of 3,581 oligonucleotides representing 94% of the gene repertoire of the B. pertussis strain Tohama I. Nine different MLST profiles and 38 different MLVA types were found in the period 1993 to 2004. Forty-three Dutch clinical isolates were analyzed with CGH, 98 genes were found to be absent in at least one of the B. pertussis strains tested, these genes were clustered in 8 distinct regions of difference.


CONCLUSIONS
The presented MLST, MLVA and CGH-analysis identified distinctive characteristics of ptxP3 B. pertussis strains -the most prominent of which was a genomic deletion removing about 23,000 bp. We propose a model for the emergence of ptxP3 strains.
King
Audrey J
AJ
Laboratory for Infectious Diseases and Screening Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands. audrey.king@rivm.nl
van Gorkom
Tamara
T
Pennings
Jeroen L A
JL
van der Heide
Han G J
HG
He
Qiushui
Q
Diavatopoulos
Dimitri
D
Heuvelman
Kees
K
van Gent
Marjolein
M
van Leeuwen
Karin
K
Mooi
Frits R
FR
D000483:Alleles; D015373:Bacterial Typing Techniques; D001886:Bordetella pertussis / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D019143:Evolution, Molecular; D020869:Gene Expression Profiling; D005787:Gene Frequency; D005798:Genes, Bacterial; D018740:Genetic Heterogeneity; D014644:Genetic Variation; D006801:Humans; D008957:Models, Genetic; D009426:Netherlands / Q000453:epidemiology; D009693:Nucleic Acid Hybridization; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D017354:Point Mutation; D012189:Retrospective Studies; D017422:Sequence Analysis, DNA; D020080:Tandem Repeat Sequences / Q000235:genetics; D014917:Whooping Cough / Q000453:epidemiology* / Q000382:microbiology
D004269:DNA, Bacterial