Genetic Transformation in Encapsulated Clinical Isolates of Haemophilus influenzae Type b

Rowji, Pradeep; Gromkova, Rosa; Koornhof, H. J.

doi:10.1099/00221287-135-10-2775

Cited by 14 publications

(10 citation statements)

References 21 publications

(11 reference statements)

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“…The fact that transformability of P. stutzeri is confined to distinct strains and not a general phenomenon of the species matches observations made with other transformable species including a B. subtilis natural population (85 % transformable strains ; Cohan et al, 1991) and H. influenzae clinical isolates (42 % transformable strains ; Rowji et al, 1989). Among the transformable P. stutzeri strains, variation of the level of competence was high (three orders of magnitude, Table 2) and thus comparable to ranges in competence found with B. subtilis and H. influenzae (Cohan et al, 1991 ;Rowji et al, 1989). It appears that some strains have a higher potential for gene acquisition than others developing low or no competence.…”

Section: Discussionsupporting

confidence: 62%

The potential for intraspecific horizontal gene exchange by natural genetic transformation: sexual isolation among genomovars of Pseudomonas stutzeri The EMBL accession numbers for the sequences reported in this paper are given in Methods.

Lorenz

Sikorski

2000

Microbiology

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The potential for natural genetic transformation among the seven genomovars (gvs) of Pseudomonas stutzeri was investigated. Of the 12 strains originating from a variety of environments, six strains (50 %) from five gvs were competent for DNA uptake (Rif R marker). The transformation frequencies varied over more than three orders of magnitude. With three highly transformable strains (ATCC 17587, ATCC 17641, JM300) from two gvs and all other strains as DNA donors, sexual isolation from other pseudomonad species (Pseudomonas alcaligenes, Pseudomonas mendocina) and also from other P. stutzeri gvs was observed (i.e. heterogamic transformation was reduced). For ATCC 17587 (gv 2) and ATCC 17641 (gv 8), heterogamic transformation was up to two and three orders of magnitude lower with other P. stutzeri gv and the other species employed, respectively, than in homogamic transformations. Interestingly, whereas with ATCC 17587 and ATCC 17641 heterogamic transformation with donors of the same gv was as high as homogamic transformation, JM300 (gv 8) was sexually isolated from its nearest relative (ATCC 17641). Also, sexual isolation of JM300 from other P. stutzeri gvs was most pronounced among the recipients tested, in some cases reaching the highest levels found with the other species as DNA donors (reduction of heterogamic transformation by 4000-fold). Results obtained here from nucleotide sequence analysis of part (422 nt) of the gene for the RNA polymerase β subunit (rpoB) from various strains indicated that sexual isolation of ATCC 17641 increased with nucleotide sequence divergence. Implications of the observed great heterogeneity in transformability, competence levels and sexual isolation among strains are discussed with regard to the evolution of P. stutzeri.

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Section: Discussionsupporting

confidence: 62%

The potential for intraspecific horizontal gene exchange by natural genetic transformation: sexual isolation among genomovars of Pseudomonas stutzeri The EMBL accession numbers for the sequences reported in this paper are given in Methods.

Lorenz

Sikorski

2000

Microbiology

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“…Similar variability in transformation frequency has also been reported in other naturally transformable bacteria, such as Actinobacillus actinomycetemcomitans (33), Haemophilus influenzae (34,35), Haemophilus parainfluenzae (36), Helicobacter pylori (37), Pseudomonas stutzeri (38), and Ralstonia solanacearum (39). However, the molecular basis and biological importance of the strain-to-strain variability in transformation frequency remain unclear in S. pneumoniae and other naturally transformable bacteria.…”

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confidence: 83%

Addiction of Hypertransformable Pneumococcal Isolates to Natural Transformation for In Vivo Fitness and Virulence

et al. 2016

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h Natural genetic transformation of Streptococcus pneumoniae, an important human pathogen, mediates horizontal gene transfer for the development of drug resistance, modulation of carriage and virulence traits, and evasion of host immunity. Transformation frequency differs greatly among pneumococcal clinical isolates, but the molecular basis and biological importance of this interstrain variability remain unclear. In this study, we characterized the transformation frequency and other associated phenotypes of 208 S. pneumoniae clinical isolates representing at least 30 serotypes. While the vast majority of these isolates (94.7%) were transformable, the transformation frequency differed by up to 5 orders of magnitude between the least and most transformable isolates. The strain-to-strain differences in transformation frequency were observed among many isolates producing the same capsule types, indicating no general association between transformation frequency and serotype. However, a statistically significant association was observed between the levels of transformation and colonization fitness/virulence in the hypertransformable isolates. Although nontransformable mutants of all the selected hypertransformable isolates were significantly attenuated in colonization fitness and virulence in mouse infection models, such mutants of the strains with relatively low transformability had no or marginal fitness phenotypes under the same experimental settings. This finding strongly suggests that the pneumococci with high transformation capability are "addicted" to a "hypertransformable" state for optimal fitness in the human host. This work has thus provided an intriguing hint for further investigation into how the competence system impacts the fitness, virulence, and other transformation-associated traits of this important human pathogen. Streptococcus pneumoniae (the pneumococcus) is a commensal in the upper airway of humans and an opportunistic pathogen for numerous infections, including pneumonia, otitis media, and meningitis (1). Genetic plasticity of S. pneumoniae mediated by horizontal gene transfer is a primary driving force behind the success of this pathogen in its adaptation to the increasingly hostile environment in humans, the only known natural host (2). S. pneumoniae is capable of horizontal gene transfer via transduction, transformation, conjugation, and specialized transduction (or pseudotransduction) (3). Natural genetic transformation, referred to as natural transformation herein, alters the bacterial genome via uptake of foreign DNA and subsequent integration of new sequences into recipient genomes by homologous recombination (4). Although natural transformation appears to be the sole mechanism of transferring chromosomal DNA in S. pneumoniae, conjugation mobilizes the transfer of integrative and conjugative elements (ICEs) between pneumococcal cells or between S. pneumoniae and other Gram-positive bacteria (3).Natural transformation has been attributed to the acquisition of exogenous genes for immune ev...

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“…injluenzae is a barrier to exogenous DNA,28 but others have demonstrated that, although the majority of strains are non-transformable, a significant proportion can undergo transformation. 29 Other factors which may explain the apparently longer clone persistence time and low frequency of recombination of capsulate strains are the low carriage rates and limited duration of carriage of these strains. 30 Long term studies will be needed to establish the persistence time of clones.…”

Section: Discussionmentioning

confidence: 99%

Clonal analysis of non-typable Haemophilus influenzae by sodium dodecyl sulphate-polyacrylamide gel electrophoresis of whole cell polypeptides

Bruce

Pennington

1991

Journal of Medical Microbiology

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Summary.A collection of 223 strains of non-typable Haemophilus inzuenzae was assembled. Most strains were isolated from hospital in-patients in North East Scotland between 1984 and 1989. These isolates were examined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of whole cell polypeptides. Variability was assessed in terms of apparent molecular weight differences between the protein profiles. Isolates were grouped on the basis of Dice coefficients of similarity and assigned to clones. Of the 223 strains, 147 were unique; the remaining strains were assigned to multi-member clones of which 13 clones had two members, one clone had three members, three clones had four members, three clones had five members, two clones had six members and one clone had eight members. The longest time interval between isolation of clonally related strains virtually equalled the limits of the study. Isolates from a childrens' hospital were significantly less diverse than those from patients in adult wards.

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Genetic Transformation in Encapsulated Clinical Isolates of Haemophilus influenzae Type b

Cited by 14 publications

References 21 publications

The potential for intraspecific horizontal gene exchange by natural genetic transformation: sexual isolation among genomovars of Pseudomonas stutzeri The EMBL accession numbers for the sequences reported in this paper are given in Methods.

The potential for intraspecific horizontal gene exchange by natural genetic transformation: sexual isolation among genomovars of Pseudomonas stutzeri The EMBL accession numbers for the sequences reported in this paper are given in Methods.

Addiction of Hypertransformable Pneumococcal Isolates to Natural Transformation for In Vivo Fitness and Virulence

Clonal analysis of non-typable Haemophilus influenzae by sodium dodecyl sulphate-polyacrylamide gel electrophoresis of whole cell polypeptides

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