Evolutionary relationships in the genus Bordetella

The nucleotide sequence of the pertussis toxin operon of Bordetella pertussis, Bordetella parapertussis and Bordetella bronchiseptica, has shown that the last two species contain many common mutations and are likely to derive from a common ancestor (Aricò and Rappuoli, 1987). To elucidate further the evolutionary relationships between the Bordetella species, we have cloned and sequenced the promoter region and the gene coding for the S1 subunit of pertussis toxin from additional B. pertussis strains, such as the type strain BP 18323 and two recent clinical isolates, namely strain BP 13456 from Sweden and strain BP SA1 from Italy. While the strains BP SA1 and BP 13456 are shown to differ from the published B. pertussis sequences by only one base pair, the type strain BP 18323 contains a total of 11 base-pair substitutions. Remarkably, 9 of the 11 substitutions found in BP 18323 are also common to B. parapertussis and B. bronchiseptica, strongly suggesting that this strain derives from the same ancestor as B. parapertussis and B. bronchiseptica. Computer analysis of the sequence data allows the construction of an evolutionary 'tree' showing that the B. pertussis strains are very homogeneous and significantly distant from B. parapertussis and B. bronchiseptica. Therefore the proposed conversion from B. parapertussis to B. pertussis appears highly improbable.     

Adaptive evolution of the Bordetella autotransporter pertactin

The virulence factor pertactin is expressed by the closely related pathogens Bordetella pertussis, Bordetella parapertussis and Bordetella bronchiseptica. Pertactin is an autotransporter involved in adherence of Bordetella species to the lung epithelium of mammalian hosts, and it is an important component of most current acellular pertussis vaccines. These three species produce immunologically distinct pertactin molecules, resulting in a lack of cross-protection against B. parapertussis and probably also against B. bronchiseptica. Variation in pertactin is not only inter-specific, but also occurs between isolates from the same species. Knowledge about codons that are under positive selection could facilitate the development of more broadly protective vaccines. Using different nucleotide substitution models, pertactin genes from B. bronchiseptica, B. parapertussis and B. pertussis were compared, and positively selected codons were identified using an empirical Bayesian approach. This approach yielded 15 codons predicted to be under diversifying selection pressure. These results were interpreted in an immunological context and may help in improving future pertussis vaccines.     

Bordetella parapertussis and Bordetella bronchiseptica contain transcriptionally silent pertussis toxin genes

Pertussis toxin, the major virulence factor of Bordetella pertussis, is not produced by the closely related species Bordetella parapertussis and Bordetella bronchiseptica. It is shown here that these two species possess but do not express the complete toxin operon. Nucleotide sequencing of an EcoRI fragment of 5 kilobases comprising the regions homologous to the pertussis toxin genes shows that in this region, B. parapertussis and B. bronchiseptica are 98.5% and 96% homologous, respectively, to B. pertussis. The changes (mostly base pair substitutions) in many cases are identical in B. parapertussis and B. bronchiseptica, suggesting that these two species derive from a common ancestor. Many of the mutations common to B. parapertussis and B. bronchiseptica involve the promoter region, which becomes very inefficient. The S1 subunits of both species, when expressed in Escherichia coli, have the same ADP-ribosylating activity as the S1 subunit from B. pertussis, indicating that the mutations in the S1 gene described here do not affect its function.     

Bordetella pertussis, the causative agent of whooping cough, evolved from a distinct, human-associated lineage of B. bronchiseptica

Bordetella pertussis, B. bronchiseptica, B. parapertussis(hu), and B. parapertussis(ov) are closely related respiratory pathogens that infect mammalian species. B. pertussis and B. parapertussis(hu) are exclusively human pathogens and cause whooping cough, or pertussis, a disease that has resurged despite vaccination. Although it most often infects animals, infrequently B. bronchiseptica is isolated from humans, and these infections are thought to be zoonotic. B. pertussis and B. parapertussis(hu) are assumed to have evolved from a B. bronchiseptica-like ancestor independently. To determine the phylogenetic relationships among these species, housekeeping and virulence genes were sequenced, comparative genomic hybridizations were performed using DNA microarrays, and the distribution of insertion sequence elements was determined, using a collection of 132 strains. This multifaceted approach distinguished four complexes, representing B. pertussis, B. parapertussis(hu), and two distinct B. bronchiseptica subpopulations, designated complexes I and IV. Of the two B. bronchiseptica complexes, complex IV was more closely related to B. pertussis. Of interest, while only 32% of the complex I strains were isolated from humans, 80% of the complex IV strains were human isolates. Comparative genomic hybridization analysis identified the absence of the pertussis toxin locus and dermonecrotic toxin gene, as well as a polymorphic lipopolysaccharide biosynthesis locus, as associated with adaptation of complex IV strains to the human host. Lipopolysaccharide structural diversity among these strains was confirmed by gel electrophoresis. Thus, complex IV strains may comprise a human-associated lineage of B. bronchiseptica from which B. pertussis evolved. These findings will facilitate the study of pathogen host-adaptation. Our results shed light on the origins of the disease pertussis and suggest that the association of B. pertussis with humans may be more ancient than previously assumed.     

Molecular evidence for the lysogenic state of microorganisms belonging to the genus Bordetella and characterization of Bordetella parapertussis temperate bacteriophage 66(2.2)

A new bacteriophage phiK of microorganisms belonging to the genus Bordetella was isolated from cells of the earlier characterized strains 66(2-2) (1 and 2) obtained upon phage conversion of B. parapertussis 17903 cells by B. pertussis bacteriophage phi134. Bacteriophage phiK is identical to previously described Bordetella bacteriophages phiT, phi134, and phi214 in morphology and some biological properties but has a permuted genome different from all other phages. DNA of bacteriophage phiK is not integrated in the chromosome of B. parapertussis 17903, similar to DNA of bacteriophages phiT, phi134, and phi214 that are not integrated into B. pertussis and B. bronchiseptica chromosomes, but may be present in a small part of the bacterial population as linear plasmids. Sequences homologous to DNA of bacteriophage phiK were detected in the chromosome of strain 66(2-2) (1 and 2) and in chromosomes of all tested strains B. pertussis and B. bronchiseptica. Prophage integration in chromosomes of microorganisms of the genus Bordetella may vary in different bacterial strains and species. An assumption about abortive lysogeny of B. parapertussis bacteria for phiK phage and of B. bronchiseptica for closely related phages phiT, phi134, and phi214 has been advanced. The possibility of involvement of B. pertussis insertion sequences in the formation of the chromosomal structure in 66(2-2) convertants and in phage genomes is considered.     

Molecular evolution and host adaptation of Bordetella spp.: phylogenetic analysis using multilocus enzyme electrophoresis and typing with three insertion sequences.

A total of 188 Bordetella strains were characterized by the electrophoretic mobilities of 15 metabolic enzymes and the distribution and variation in positions and copy numbers of three insertion sequences (IS). The presence or absence of IS elements within certain lineages was congruent with estimates of overall genetic relationships as revealed by multilocus enzyme electrophoresis. Bordetella pertussis and ovine B. parapertussis each formed separate clusters, while human B. parapertussis was most closely related to IS1001-containing B. bronchiseptica isolates. The results of the analysis provide support for the hypothesis that the population structure of Bordetella is predominantly clonal, with relatively little effective horizontal gene flow. Only a few examples of putative recombinational exchange of an IS element were detected. Based on the results of this study, we tried to reconstruct the evolutionary history of different host-adapted lineages.     

Agglutination of Bordetella species by lectins

Phase I cells of Bordetella pertussis but not those of B. parapertussis, B. bronchiseptica or B. avium were agglutinated by Limulus polyphemus lectin. Most strains of B. pertussis but not those of the other species were also agglutinated by Helix pomatia lectin. In precipitation reactions between lectins and purified Bordetella lipopolysaccharide (LPS) preparations a similar pattern occurred. Lectin agglutination provides a rapid presumptive method for the differentiation of B. pertussis from B. parapertussis and other Bordetella species.     

Biochemical and immunological comparison of lipopolysaccharides from Bordetella species

Lipopolysaccharides (LPS) isolated from Bordetella pertussis, B. parapertussis and B. bronchiseptica were analysed for their chemical composition, molecular heterogeneity and immunological properties. All the LPS preparations contained heptose, 3-deoxy-D-manno-2-octulosonic acid, glucosamine, uronic acid, phosphate and fatty acids. The fatty acids C14:0, C16:0 and beta OHC14:0 were common to all the LPS preparations. LPS from B. pertussis strains additionally contained isoC16:0, those from B. parapertussis contained isoC14:0 and isoC16:0, and those from B. bronchiseptica contained C16:1. By SDS-PAGE, LPS from B. pertussis had two bands of low molecular mass, and the LPS from B. parapertussis and B. bronchiseptica showed low molecular mass bands together with a ladder arrangement of high molecular mass bands. Immunodiffusion, quantitative agglutination and ELISA demonstrated that the LPS from B. pertussis strains reacted with antisera prepared against whole cells of B. pertussis and B. bronchiseptica; LPS from B. parapertussis reacted with antisera to B. parapertussis and B. bronchiseptica, and LPS from B. bronchiseptica reacted with anti-whole cell serum raised against any of the three species. From these results, it is concluded that LPS from B. bronchiseptica has structures in common with LPS from B. pertussis and B. parapertussis, while the LPS from B. pertussis and B. parapertussis are serologically entirely different from each other.     

The type III secreted protein BspR regulates the virulence genes in Bordetella bronchiseptica

Bordetella bronchiseptica is closely related with B. pertussis and B. parapertussis, the causative agents of whooping cough. These pathogenic species share a number of virulence genes, including the gene locus for the type III secretion system (T3SS) that delivers effector proteins. To identify unknown type III effectors in Bordetella, secreted proteins in the bacterial culture supernatants of wild-type B. bronchiseptica and an isogenic T3SS-deficient mutant were compared with iTRAQ-based, quantitative proteomic analysis method. BB1639, annotated as a hypothetical protein, was identified as a novel type III secreted protein and was designated BspR (Bordetella secreted protein regulator). The virulence of a BspR mutant (ΔbspR) in B. bronchiseptica was significantly attenuated in a mouse infection model. BspR was also highly conserved in B. pertussis and B. parapertussis, suggesting that BspR is an essential virulence factor in these three Bordetella species. Interestingly, the BspR-deficient strain showed hyper-secretion of T3SS-related proteins. Furthermore, T3SS-dependent host cell cytotoxicity and hemolytic activity were also enhanced in the absence of BspR. By contrast, the expression of filamentous hemagglutinin, pertactin, and adenylate cyclase toxin was completely abolished in the BspR-deficient strain. Finally, we demonstrated that BspR is involved in the iron-responsive regulation of T3SS. Thus, Bordetella virulence factors are coordinately but inversely controlled by BspR, which functions as a regulator in response to iron starvation.     

Structural and genetic analysis of the bvg locus in Bordetella species

The bvg locus contains two genes, bvgA and bvgS, which control the expression of the virulence-associated genes in Bordetella species by a system similar to the two-component systems used by a variety of bacterial species to respond to environmental stimuli. We determined the nucleotide sequence of the bvg loci of Bordetella parapertussis and Bordetella bronchiseptica and compared them with the previously determined sequence of Bordetella pertussis. The nucleotide and amino acid sequences of the bvg loci of these species are well conserved in those regions coding for the protein domains which have putative kinase and DNA-binding activities. In marked contrast, the region of BvgS that codes for the protein domain with putative sensor activity shows a high degree of variability. In total, we find 198 base-pair changes in the bvg loci of B. parapertussis and B. bronchiseptica relative to the bvg locus of B. pertussis. One hundred and seventy-three of these base-pair changes are identical in B. parapertussis and B. bronchiseptica. This confirms our previous observation that B. parapertussis and B. bronchiseptica are more related to each other than to B. pertussis. We have mapped the mutations that cause phase changes in B. bronchiseptica and we have found that in three cases these are due to spontaneous deletions in the bvgS gene. The wild-type bvg locus present on a multicopy plasmid cannot complement avirulent derivatives of B. bronchiseptica to wild-type levels, but it can do so when the bvgA gene on the plasmid is inactivated. This suggests that hyperexpression of bvgA down-regulates the bvg system.     

Chromosomal DNA from both flagellate and non-flagellate Bordetella species contains sequences homologous to the Salmonella H1 flagellin gene

Abstract The genus Bordetella contains four species: two are non-motile, the human pathogens B. pertussis and B. parapertussis ; and two are motile, the broad host-range mammalian pathogen B. bronchiseptica , and the avian pathogen B. avium . The motility of the latter two species is due to peritrichous flagella. Here we show that strains of all four species contain DNA sequences homologous to flagellin genes. Two types of gene probe were hybridised to Bordetella chromosomal DNA in Southern blots: the structural gene for H1 flagellin of Salmonella typhimurium and an oligonucleotide derived from the conserved N-terminal amino acid sequences of various flagellin proteins. Cla I-digested DNA from all four Bordetella species hybridised with both probes in Southern blots, although each species gave a characteristic pattern of hybridisation. This indicates that the non-motile B. pertussis and B. parapertussis species contain non-expressed flagellin genes.     

Bordetella bronchiseptica expresses the fimbrial structural subunit gene fimA.

The differential host species specificities of Bordetella pertussis, B. parapertussis, and B. bronchiseptica might be explained by polymorphisms in adherence factor genes. We have found that B. parapertussis and B. bronchiseptica, unlike B. pertussis, contain a full-length gene for the fimbrial subunit FimA. B. bronchiseptica expresses fimA in a BvgAS-dependent fashion.     

Detection of the gene sequences of the leukocytosis (lymphocytosis)-stimulating factor of Bordetella pertussis in Bordetella parapertussis and Bordetella bronchiseptica by using molecular hybridization

The 4.7 Kb EcoRI-fragment of phase I B. pertussis 475 (serovar 1.2.3) chromosome DNA carrying the pertussis toxin (PT) operon was cloned on vector plasmid pUC19 in Escherichia coli. Three fragments (1.14 Kb KpnI-PstI, 1.27 Kb PstI-PstI, and 0.96 Kb PstI-PstI) were obtained from the resulting hybrid plasmid, coded pRH119, by electrophoretic techniques and used as a combined molecular probe for analysis of the EcoRI-digested and PstI-digested chromosomal DNA of B. pertussis strain 475 in phase I, B. pertussis in phase IV, B. parapertussis strains 504 and 17903, B. bronchiseptica strain 214, and B. parapertussis strain 17903 (a convertant obtained by means of B. pertussis phage 134), as well as B. pertussis phage 134. Southern blot hybridization under the conditions of 100% DNA-DNA homology showed the presence of DNA sequences characteristic of the PT operon in all cases except the DNA of phage 134; moreover, the use of the above-mentioned probe made it possible to hybridize all EcoRI-fragments of chromosomal DNA, having the same molecular size (4.7 Kb). Consequently, the PT genes in the above Bordetella species were mapped in identical loci.(ABSTRACT TRUNCATED AT 250 WORDS)     

Detection of Bordetella bronchiseptica strains containing the main agglutinogens of all species of the genus Bordetella

The study of 26 B. bronchiseptica strains with typical morphological and biochemical properties resulted in the detection of 8 strains having the main specific agglutinogens of 3 Bordetella species (serovars) in different combinations. The presence of the agglutinogens was confirmed in the agglutination test and the agglutinin adsorption test with the use of monospecific antisera to the main agglutinogens. The comparison of natural B. bronchiseptica serovars and artificial convertants (resulting from the conversion of B. parapertussis by B. pertussis phages) revealed their identical biochemical activity, their capacity for causing necrosis when injected intradermally into rabbits and for the formation of two types of colonies, differing in size and serological activity. In contrast to B. parapertussis convertants, B. bronchiseptica serovars had no lysogenic properties and were sensitive to B. pertussis and B. bronchiseptica phages.     

Examination of the genus Bordetella for specific human IgA protease activity

Abstract Three laboratory strains and 3 clinical isolates of Bordetella pertussis were found to have no IgA protease activity when incubated with radio-labelled IgA. In addition, no IgA protease activity was detected in the Second British Reference Preparation for Pertussis Vaccine, an acellular vaccine produced in Japan, or one strain each of Bordetella parapertussis and Bordetella bronchiseptica .     

Genetics of pertussis toxin

Pertussis toxin (PT) is the major virulence factor of Bordetella pertussis. The cloning and nucleotide sequencing of the PT genes from B. pertussis, Bordetella parapertussis and Bordetella bronchiseptica has elucidated the evolution of the Bordetella species and allowed considerable advances towards the understanding of their gene expression and the development of safer vaccines against pertussis.     

IgA protease activity of microbes in the genus Bordetella

Monoclonal IgA paraproteins of subclasses 1 and 2, isolated from the sera of myeloma patients, were incubated for 4, 24, 48 and 72 hours with B. pertussis, B. parapertussis, B. bronchiseptica cultures, as well as Haemophilus influenzae strain. The fragmentation of IgA was studied by immunielectrophoresis with antisera to alpha-chain, to Fab alpha + Fc alpha, to Fab alpha and with antisera to light chains corresponding to the type of paraprotein. B. pertussis and B. parapertussis were found to have subclass-unspecific IgA protease which splitted off a cathode fragment, similar to Fab-fragment and, probably, corresponding to the variable domain of alpha-chain (Fv), after 48-hour incubation. Similar IgA protease was detected in H. influenzae, found to have classical IgA1 protease as well. All Bordetella species under study splitted off anode components from IgA paraproteins of both subclasses. These components, containing the determinants of heavy and light IgA chains, were either IgA - alpha I-antitrypsin complexes or some IgA fragments with high electrophoretic motility. None of the strains under study splitted monoclonal IgG.     

Characteristic lipids of Bordetella pertussis: simple fatty acid composition, hydroxy fatty acids, and an ornithine-containing lipid.

The lipids and fatty acids of Bordetella pertussis (phases I to IV) were analyzed by thin-layer chromatography, gas-liquid chromatography, and mass spectrometry and compared with those of B. parapertussis and B. bronchiseptica. The major lipid components of the three species were phosphatidylethanolamine, cardiolipin, phosphatidylglycerol, lysophosphatidylethanolamine, and an ornithine-containing lipid. The ornithine-containing lipid was characteristic of the genus Bordetella. The fatty acid composition of the total extractable cellular lipids of B. pertussis was mostly hexadecanoic and hexadecenoic acids (90%) in a ratio of about 1:1. The hexadecenoic acid of B. pertussis was in the cis-9 form. The fatty acid composition of the residual bound lipids was distinctly different from that of the extractable lipids, and residual bound lipids being mainly 3-hydroxytetradecanoic, tetradecanoic, and 3-hydroxydecanoic acids, with 3-hydroxydodecanoic acid occurring in some strains. It was determined that the 3-hydroxy fatty acids were derived from lipid A. The fatty acid composition of the total extractable cellular lipids of B. parapertussis and B. bronchiseptica, mainly composed of hexadecanoic and heptadecacyclopropanoic acid, differed from that of B. pertussis. Although the fatty acid composition of the residual bound lipids of B. parapertussis was similar to that of the residual bound lipids of B. pertussis, 2-hydroxydodecanoic acid was detected only in the bound lipids of B. bronchiseptica.     

Adenylate cyclase activity of Bordetella organisms. I. Its production in liquid medium

Abundant adenylate cyclase activity was found in the phase I cultures not only of Bordetella pertussis but also fo B. parapertussis and B. bronchiseptica. The enzyme activity in the culture fluid increased rapidly and reached a peak during the logarithmic growth phase. B. parapertussis and B. bronchiseptica especially produced a high activity of the enzyme in the culture fluid during the logarithmic phase, but little or no activity was detected in the cells throughout the growth period. In the culture of B. pertussis, the intracellular activity was higher than that in the culture fluid. Phase III cultures of these species lacked both the extracellular and intracellular enzyme activities throughout their growth. In the culture of B. parapertussis, accumulation of cyclic AMP was parallel to that of adenylate cyclase activity through the growth periods, but in B. pertussis there was no parallelism from the stationary through the declining phases. The difference in production patterns of the enzyme activity among the species is discussed.     

Variability in LPS composition, antigenicity and reactogenicity of phase variants of Bordetella pertussis

Comparison of lipopolysaccharides (LPS) from phase variants of different strains of Bordetella phase variants of different strains of Bordetella pertussis has shown a difference in their composition, antigenicity and reactogenicity. Phase I variants of B. pertussis, with the exception of strain 134, contain a preponderance of LPS I whereas the major component of LPS of phase IV variants is LPS II. Sera raised to LPSs of phase I strains, other than 134, cross-react with each other but not with phase IV LPSs; and similarly all sera raised to phase IV LPSs cross-react with each other and with LPS from 134 phase I. The LPSs of all phase I variants, including that of 134, are approximately ten-fold or more reactive in the limulus amoebocyte lysate assay (LAL) than phase IV LPSs. In the human mononuclear cell pyrogen assay phase IV LPSs also stimulated a lower response than phase I LPSs. The B. pertussis phase I LPSs are 10-times more reactive than Escherichia coli standard endotoxin in the LAL assay but 100-times less reactive than E. coli LPS in the monocyte test for pyrogen. The SDS-PAGE profiles of B. pertussis LPSs are quite different from those of B. parapertussis and B. bronchiseptica strains. B. pertussis LPSs produced a typical lipo-oligosaccharide (LOS) pattern. B. bronchiseptica LPS produced a similar pattern but was antigenically distinct from B. pertussis LPSs I and II. B. parapertussis in contrast produced a ladder pattern typical of smooth type LPS.