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Long-term evolution of antigen repertoires among carried meningococci.

Buckee CO, Gupta S, Kriz P, Maiden MC, Jolley KA - Proc. Biol. Sci. (2010)

Bottom Line: For commensal organisms that occasionally cause disease, such as Neisseria meningitidis, however, the analysis of isolates from long-term asymptomatic carriage is necessary to elucidate their evolution and population structure.The data indicate that stable combinations of antigenic alleles were maintained over this time period despite evidence for high rates of recombination, consistent with theoretical models in which strong immune selection can maintain non-overlapping combinations of antigenic determinants in the presence of recombination.We contrast this antigenic structure with the overlapping but relatively stable combinations of the housekeeping genes observed among the same isolates, and use a novel network approach to visualize these relationships.

View Article: PubMed Central - PubMed

Affiliation: Department of Zoology, University of Oxford, Oxford OX1 3PS, UK. caroline.buckee@zoo.ox.ac.uk

ABSTRACT
Most studies of bacterial pathogen populations have been based on isolates collected from individuals with disease, or their contacts, over short time periods. For commensal organisms that occasionally cause disease, such as Neisseria meningitidis, however, the analysis of isolates from long-term asymptomatic carriage is necessary to elucidate their evolution and population structure. Here, we use mathematical models to analyse the structuring and dynamics of three vaccine-candidate antigens among carried meningococcal isolates collected over nearly 30 years in the Czech Republic. The data indicate that stable combinations of antigenic alleles were maintained over this time period despite evidence for high rates of recombination, consistent with theoretical models in which strong immune selection can maintain non-overlapping combinations of antigenic determinants in the presence of recombination. We contrast this antigenic structure with the overlapping but relatively stable combinations of the housekeeping genes observed among the same isolates, and use a novel network approach to visualize these relationships.

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The longevity and prevalence of PorA VR2∶FetA VR variant combinations in the dataset. Each bar represents a particular combination of variants that are seen at least twice within the dataset and their order is determined by their frequencies in successive time periods.
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RSPB20092033F3: The longevity and prevalence of PorA VR2∶FetA VR variant combinations in the dataset. Each bar represents a particular combination of variants that are seen at least twice within the dataset and their order is determined by their frequencies in successive time periods.

Mentions: Distinct structuring of associations for some of the most prevalent FetA variants with respect to the PorA variants was apparent when individual years were examined (figure 3). Each FetA allele was primarily associated with one combination of PorA VR1∶VR2, although this changed over time. For example, the FetA allele F3-6 was associated with PorA VR combination 18-1∶3 in the 1970s, and with 10-1∶5-1 in the 1990s. The relationship was not reciprocated, however, with one VR1∶VR2 allele combination being associated with a number of FetA alleles at any point in time, resulting in a low-scoring f* value. Thus, the FetA variable region showed strong associations with the PorA variable regions, but on a relatively short time scale.


Long-term evolution of antigen repertoires among carried meningococci.

Buckee CO, Gupta S, Kriz P, Maiden MC, Jolley KA - Proc. Biol. Sci. (2010)

The longevity and prevalence of PorA VR2∶FetA VR variant combinations in the dataset. Each bar represents a particular combination of variants that are seen at least twice within the dataset and their order is determined by their frequencies in successive time periods.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2871849&req=5

RSPB20092033F3: The longevity and prevalence of PorA VR2∶FetA VR variant combinations in the dataset. Each bar represents a particular combination of variants that are seen at least twice within the dataset and their order is determined by their frequencies in successive time periods.
Mentions: Distinct structuring of associations for some of the most prevalent FetA variants with respect to the PorA variants was apparent when individual years were examined (figure 3). Each FetA allele was primarily associated with one combination of PorA VR1∶VR2, although this changed over time. For example, the FetA allele F3-6 was associated with PorA VR combination 18-1∶3 in the 1970s, and with 10-1∶5-1 in the 1990s. The relationship was not reciprocated, however, with one VR1∶VR2 allele combination being associated with a number of FetA alleles at any point in time, resulting in a low-scoring f* value. Thus, the FetA variable region showed strong associations with the PorA variable regions, but on a relatively short time scale.

Bottom Line: For commensal organisms that occasionally cause disease, such as Neisseria meningitidis, however, the analysis of isolates from long-term asymptomatic carriage is necessary to elucidate their evolution and population structure.The data indicate that stable combinations of antigenic alleles were maintained over this time period despite evidence for high rates of recombination, consistent with theoretical models in which strong immune selection can maintain non-overlapping combinations of antigenic determinants in the presence of recombination.We contrast this antigenic structure with the overlapping but relatively stable combinations of the housekeeping genes observed among the same isolates, and use a novel network approach to visualize these relationships.

View Article: PubMed Central - PubMed

Affiliation: Department of Zoology, University of Oxford, Oxford OX1 3PS, UK. caroline.buckee@zoo.ox.ac.uk

ABSTRACT
Most studies of bacterial pathogen populations have been based on isolates collected from individuals with disease, or their contacts, over short time periods. For commensal organisms that occasionally cause disease, such as Neisseria meningitidis, however, the analysis of isolates from long-term asymptomatic carriage is necessary to elucidate their evolution and population structure. Here, we use mathematical models to analyse the structuring and dynamics of three vaccine-candidate antigens among carried meningococcal isolates collected over nearly 30 years in the Czech Republic. The data indicate that stable combinations of antigenic alleles were maintained over this time period despite evidence for high rates of recombination, consistent with theoretical models in which strong immune selection can maintain non-overlapping combinations of antigenic determinants in the presence of recombination. We contrast this antigenic structure with the overlapping but relatively stable combinations of the housekeeping genes observed among the same isolates, and use a novel network approach to visualize these relationships.

Show MeSH