Molecular Typing of<i>Neisseria gonorrhoeae</i>Causing Repeated Infections: Evolution of Porin during Passage within a Community

Hobbs, Marcia M.; Alcorn, Timothy M.; Davis, Rachael H.; Fischer, William; Thomas, James C.; Martin, Iona; Ison, Catherine; Sparling, P. Frederick; Cohen, Myron S.

doi:10.1086/314608

Cited by 72 publications

(81 citation statements)

References 54 publications

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“…However, the protein has shown antigenic variation over time, as revealed by the diversity of serovars (21) and porB genes (11) identified in the N. gonorrhoeae isolates derived from patients in sexual networks. Sequence analysis of porB genes has previously indicated the presence of horizontal genetic exchange, including the exchange of the entire gene or segments of the gene, as well as point mutations in the evolution of the porin during circulation within the community (3,11,14,23). However, more knowledge concerning the mechanisms and time scale by which changes in the porB genes occur is required.…”

Section: Vol 40 2002 Sequence Analysis Of N Gonorrhoeae Porb Gene mentioning

confidence: 99%

“…Conventional characterization of N. gonorrhoeae strains for epidemiological and clinical purposes is mostly based on auxotyping, serovar designation, and antibiograms. However, these phenotypic systems have some inherent limitations concerning, for instance, their discriminatory abilities and reproducibilities (12,14,15,18,27). Different DNAbased methods have thus been developed (14,19,26,28,29,30,33).…”

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confidence: 99%

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Molecular Epidemiology of Neisseria gonorrhoeae : Sequence Analysis of the porB Gene Confirms Presence of Two Circulating Strains

et al. 2002

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The phenotypic and genotypic characteristics of Neisseria gonorrhoeae strains fluctuate over time both locally and globally, and highly discriminative and precise characterization of the strains is essential. Conventional characterization of N. gonorrhoeae strains for epidemiological purposes is mostly based on phenotypic methods, which have some inherent limitations. In the present study sequence analysis of porB1b gene sequences was used for examination of the genetic relationships among N. gonorrhoeae strains. Substantial genetic heterogeneity was identified in the porB genes of serovar IB-2 isolates (8.1% of the nucleotide sites were polymorphic) and serovar IB-3 isolates (5.2% of the nucleotide sites were polymorphic) as well as between isolates of different serovars. The highest degree of diversity was identified in the gene segments encoding the surface-exposed loops of the mature PorB protein. Phylogenetic analysis of the porB1b gene sequences confirmed previous findings that have indicated the circulation of one N. gonorrhoeae strain each of serovar IB-2 and serovar IB-3 in the Swedish community. These strains caused the majority of the cases in two domestic core groups comprising homosexual men and young heterosexuals, respectively, and were also detected in other patients. The phylogenetic analyses of porB gene sequences in the present study showed congruence, but not complete identity, with previous results obtained by pulsed-field gel electrophoresis of the same isolates. In conclusion, porB gene sequencing can be used as a molecular epidemiological tool for examination of genetic relationships among emerging and circulating N. gonorrhoeae strains, as well as for confirmation or discrimination of clusters of gonorrhea cases.

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Section: Vol 40 2002 Sequence Analysis Of N Gonorrhoeae Porb Gene mentioning

confidence: 99%

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confidence: 99%

Molecular Epidemiology of Neisseria gonorrhoeae : Sequence Analysis of the porB Gene Confirms Presence of Two Circulating Strains

et al. 2002

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“…Thus, for epidemiological and clinical purposes a highly discriminating, objective, and reproducible characterization of N. gonorrhoeae strains is essential. The widely used phenotypic characterizations of the bacterium have several limitations (10,12,13,17,24,27,28), and different molecular genetic methods have thus been developed (12,15,18,23,25,26,27,28,30,32).…”

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confidence: 99%

“…Previous genetic studies have concluded that porB gene sequencing can be used to trace the transmission of individual N. gonorrhoeae strains within the community, discriminate suspected clusters of gonorrhea cases, and confirm epidemiological connections of patients (5,12,28,31). The segments of the porB gene encoding the eight surface-exposed amino acid loops of PorB (29) exhibit the highest level of polymorphism (1,4,5,7,12,27,28,29,31).…”

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Molecular Typing of Neisseria gonorrhoeae Isolates by Pyrosequencing of Highly Polymorphic Segments of the porB Gene

et al. 2004

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For prevention and control of gonorrhea, an objective, highly discriminating, and reproducible molecular epidemiological characterization of Neisseria gonorrhoeae is essential. In the present study, in pursuance of providing such qualities, pyrosequencing technology, a fast real-time DNA sequence analysis, was applied to six short, highly polymorphic porB gene segments, with subsequent genetic variant (genovar) determination of the bacterial isolates. The sequencing templates were obtained by real-time PCR amplification, which also included fluorescence melting curve analysis of the entire porB gene in order to determine the genogroup (porB1a or porB1b allele) prior to pyrosequencing analysis. The PSQ 96 MA system used allowed rapid (in approximately 1.5 h) determination of 96 sequences of 20 to 65 correct nucleotides each. The results were reproducible and mostly in concordance with the results of conventional Sanger dideoxy sequencing, with the exception of shorter read lengths and some uncertainty in determining the correct number of identical nucleotides in homopolymeric segments. The number of sequence variants identified in each of the six highly polymorphic segments of the porB1a and porB1b alleles (encoding surface-exposed amino acid loops of the mature PorB protein) ranged from 5 to 11 and from 8 to 39, respectively. Among porB1a isolates (n ‫؍‬ 22) and porB1b isolates (n ‫؍‬ 65), 22 and 64 unique genovars, respectively, were identified. All isolates were typeable. The present results provide evidence of a high discriminatory ability, practically the same as that for sequencing of the entire porB gene. In conclusion, the fast and high-throughput pyrosequencing technology can be used for molecular epidemiological characterization of N. gonorrhoeae.

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“…The introduction of PCR and high-throughput nucleotide sequencing has led to the development of several DNA-based typing methods. Two methods that are highly discriminating are the opa gene (OPA) typing method and sequencing of the porB gene (POR sequencing), which we as well as others have employed (11,16,18,22). A disadvantage of the above two methods is that variation at these loci is evolving rapidly and for reasons that are not fully understood, although immune selection plays an important role.…”

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Genetic Diversity of Neisseria gonorrhoeae Housekeeping Genes

Viscidi

Demma

2003

J Clin Microbiol

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Molecular typing of Neisseria gonorrhoeae strains is an important tool for epidemiological studies of gonococcal infection and transmission. The recently developed multilocus sequence typing (MLST) method is based on the genetic variation among housekeeping genes. As a preliminary investigation for the development of such a method, we characterized the genetic diversity at 18 gonococcal housekeeping gene loci. Approximately 17,500 nucleotides, spanning 18 loci, were sequenced from 24 isolates. Including strain FA 1090, which has been fully sequenced, and three unique glnA sequences from GenBank, the number of alleles identified for the 18 loci ranged from 2 to 18, with a mean of 8.3 alleles per locus. The majority of polymorphic sites were distributed randomly along the genes, consistent with evolution of DNA sequences by point mutation. In addition, several examples of clustered mutations and insertions or deletions were detected, which most likely occurred by recombinational events. While purifying selection is the dominant force driving the evolution of these housekeeping genes, positive selection also appeared to operate on the abcZ and gpdh loci. The 25 completely characterized strains each had a unique allelic profile with as few as three loci (pilA, abcZ, and pip or pgi2). Molecular typing based on the allelic profile of housekeeping genes resolved the isolates better than either porB nucleotide sequencing or typing of the opa gene. The allelic profiles for the pilA, abcZ, and serC loci of paired strains from 16 sexual contacts were identical. A potential MLST for N. gonorrhoeae, based on ϳ500-to 600-bp gene fragments of seven housekeeping gene loci, would include the pilA, abcZ, serC, glnA, gdh, gnd, and pip loci.

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Molecular Typing ofNeisseria gonorrhoeaeCausing Repeated Infections: Evolution of Porin during Passage within a Community

Cited by 72 publications

References 54 publications

Molecular Epidemiology of Neisseria gonorrhoeae : Sequence Analysis of the porB Gene Confirms Presence of Two Circulating Strains

Molecular Epidemiology of Neisseria gonorrhoeae : Sequence Analysis of the porB Gene Confirms Presence of Two Circulating Strains

Molecular Typing of Neisseria gonorrhoeae Isolates by Pyrosequencing of Highly Polymorphic Segments of the porB Gene

Genetic Diversity of Neisseria gonorrhoeae Housekeeping Genes

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