RESUMO
Three Bordetella pertussis typing methods, pulsed-field gel electrophoresis (PFGE), multi-locus sequence typing (MLST), and multi-locus variable number tandem repeat analysis (MLVA) were compared using a collection of Swedish strains. Of the three typing methods used, PFGE was found to be the most discriminatory. MLVA and MLST were less discriminatory, but may be valuable for strain discrimination when culture is not possible as they are based on PCR. The combination of MLVA/MLST was found to be equally discriminatory as PFGE and should therefore also be considered. The relationship between predominant lineages in Sweden and The Netherlands, characterized by the PFGE type BpSR11 and the allele for the pertussis toxin promoter ptxP3, respectively, was investigated. Linkage was found between the PFGE type BpSR11 and ptxP3 in that all BpSR11 strains carried ptxP3. On the other hand ptxP3 was found in several other PFGE-types. The presence of the ptxP3 allele in different genetic backgrounds may indicate horizontal gene transfer within B. pertussis or homoplasy. Alternatively, this observation may be due to convergence of PFGE types.
Assuntos
Técnicas de Tipagem Bacteriana/métodos , Bordetella pertussis/classificação , Bordetella pertussis/genética , Impressões Digitais de DNA/métodos , Coqueluche/epidemiologia , Coqueluche/microbiologia , Alelos , Bordetella pertussis/isolamento & purificação , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , Eletroforese em Gel de Campo Pulsado/métodos , Humanos , Repetições Minissatélites , Epidemiologia Molecular/métodos , Dados de Sequência Molecular , Reação em Cadeia da Polimerase/métodos , Sensibilidade e Especificidade , Análise de Sequência de DNA/métodos , Suécia/epidemiologiaRESUMO
The recently discovered pathogen Bordetella holmesii has been isolated from the airways and blood of diseased humans. Genetic events contributing to the emergence of B. holmesii are not understood, and its phylogenetic position among the bordetellae remains unclear. To address these questions, B. holmesii strains were analyzed by comparative genomic hybridization (CGH) to a Bordetella pertussis microarray and by multilocus sequence typing. Both methods indicated substantial sequence divergence between B. pertussis and B. holmesii. However, CGH identified a putative pathogenicity island of 66 kb that is highly conserved between these species and contains several IS481 elements that may have been laterally transferred from B. pertussis to B. holmesii. This island contains, among other genes, a functional, iron-regulated locus encoding the biosynthesis, export, and uptake of the siderophore alcaligin. The acquisition of this genomic island by B. holmesii may have significantly contributed to its emergence as a human pathogen. Horizontal gene transfer between B. pertussis and B. holmesii may also explain the unusually high sequence identity of their 16S rRNA genes.
Assuntos
Bordetella pertussis/classificação , Bordetella pertussis/genética , Bordetella/classificação , Bordetella/genética , Ilhas Genômicas/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Bordetella/isolamento & purificação , Bordetella pertussis/isolamento & purificação , Evolução Molecular , Genoma Bacteriano , Humanos , Ácidos Hidroxâmicos/metabolismo , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , Análise de Sequência com Séries de Oligonucleotídeos , Filogenia , Análise de Sequência de DNARESUMO
Despite the widespread use of pertussis vaccines during the last decades, pertussis has remained an endemic disease with frequent epidemic outbreaks. Currently two types of vaccines are used: whole-cell vaccines (WCVs) and recently developed acellular vaccines (ACVs). The long-term aim of our studies is to assess the effect of different vaccination policies on the population structure of Bordetella pertussis and ultimately on the disease burden in Europe. In the present study, a total of 102 B. pertussis isolates from the period 1998 to 2001 from five European countries (Finland, Sweden, Germany, The Netherlands, and France) were characterized. The isolates were analyzed by typing based on variable number of tandem repeats (VNTR); by sequencing of polymorphic genes encoding the surface proteins pertussis toxin S1 and S3 subunits (ptxA and ptxC), pertactin (prn), and tracheal colonization factor (tcfA); and by fimbrial serotyping. The results reveal a relationship between geographic location and VNTR types, the frequency of the ptxC alleles, and serotypes. We have not observed a relationship between the strain characteristics we studied and vaccination programs. Our results provide a baseline which can be used to reveal changes in the B. pertussis population in Europe in the coming years.
