SNP-Based Typing: A Useful Tool to Study Bordetella pertussis Populations
نویسندگان
چکیده
To monitor changes in Bordetella pertussis populations, mainly two typing methods are used; Pulsed-Field Gel Electrophoresis (PFGE) and Multiple-Locus Variable-Number Tandem Repeat Analysis (MLVA). In this study, a single nucleotide polymorphism (SNP) typing method, based on 87 SNPs, was developed and compared with PFGE and MLVA. The discriminatory indices of SNP typing, PFGE and MLVA were found to be 0.85, 0.95 and 0.83, respectively. Phylogenetic analysis, using SNP typing as Gold Standard, revealed false homoplasies in the PFGE and MLVA trees. Further, in contrast to the SNP-based tree, the PFGE- and MLVA-based trees did not reveal a positive correlation between root-to-tip distance and the isolation year of strains. Thus PFGE and MLVA do not allow an estimation of the relative age of the selected strains. In conclusion, SNP typing was found to be phylogenetically more informative than PFGE and more discriminative than MLVA. Further, in contrast to PFGE, it is readily standardized allowing interlaboratory comparisons. We applied SNP typing to study strains with a novel allele for the pertussis toxin promoter, ptxP3, which have a worldwide distribution and which have replaced the resident ptxP1 strains in the last 20 years. Previously, we showed that ptxP3 strains showed increased pertussis toxin expression and that their emergence was associated with increased notification in The Netherlands. SNP typing showed that the ptxP3 strains isolated in the Americas, Asia, Australia and Europe formed a monophyletic branch which recently diverged from ptxP1 strains. Two predominant ptxP3 SNP types were identified which spread worldwide. The widespread use of SNP typing will enhance our understanding of the evolution and global epidemiology of B. pertussis.
منابع مشابه
VNTR9 and VNTR10, two newly-found variable-number tandem repeat loci useful in MLVA genotyping of Bordetella pertussis
Background & Aims: Bordetella pertussis, the causative agent of whooping cough, continues to infect human hosts even in those populations where infants and children are routinely vaccinated. Causes of pertussis epidemiology are not fully identified unless strains of the pathogen are characterized by molecular means. Golbally, Multi Locus Variable Number of Tandem Repeats analysis (MLVA) has pro...
متن کاملRegulation of pertussis toxin and lipopolysaccharide levels of Bordetella pertussis 134 in response to modulators
Whooping cough (pertussis) is a highly contagious disease of the human respiratory tract, which is caused by Bordetella pertussis. Reemerge of pertussis in some highly immunized populations and divergency in gene order among several B. pertussis strains promoted this research to study the change of pertussis toxin (PT) and lipopolysacharide levels in response to the different environments. Th...
متن کاملStudying Bordetella pertussis populations by use of SNPeX, a simple high-throughput single nucleotide polymorphism typing method.
Large outbreaks of pertussis occur despite vaccination. A first step in the analyses of outbreaks is strain typing. However, the typing of Bordetella pertussis, the causative agent of pertussis, is problematic because the available assays are insufficiently discriminatory, not unequivocal, time-consuming, and/or costly. Here, we describe a single nucleotide primer extension assay for the study ...
متن کاملA study on the genetic analysis of clinical isolates and vaccine strains of Bordetella pertussis by pulsed-field gel electrophoresis (PFGE)
Considering the circulation of Bordetella pertussis clinical strains among populations with high vaccination coverage, it is necessary to have a proper understanding of this bacterium causing whooping cough. Various techniques, which are available for studying B. pertussis, can facilitate a proper comparison between different populations. We genotypically analyzed a collection of two vaccine st...
متن کامل