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Optimization of Molecular Approaches to Genogroup Neisseria meningitidis Carriage Isolates and Implications for Monitoring the Impact of New Serogroup B Vaccines.

Rojas E, Hoyos J, Oldfield NJ, Lee P, Flint M, Jones CH, Ala'Aldeen DA, Jansen KU, Anderson AS - PLoS ONE (2015)

Bottom Line: Isolates were typed for the Nm vaccine antigen factor H binding protein (fHbp), and were found to represent the known diversity of this antigen.Thirty seven NGG isolates evidenced a disrupted capsular polysaccharide operon judged by a ctrA negative result.Only 28.6% (67/234) of the isolates were serogrouped by slide agglutination (SASG), highlighting the reduced capability of carriage strains to express capsular polysaccharide.

View Article: PubMed Central - PubMed

Affiliation: Vaccine Research and Development, Pfizer Inc, Pearl River, New York, United States of America.

ABSTRACT
The reservoir for Neisseria meningitidis (Nm) is the human oropharynx. Implementation of Nm serogroup C (NmC) glycoconjugate vaccines directly reduced NmC carriage. Prophylactic vaccines are now available to prevent disease caused by the five major Nm disease causing serogroups (ABCWY). Nm serogroup B (NmB) vaccines are composed of antigens that are conserved across Nm serogroups and therefore have the potential to impact all Nm carriage. To assess the effect of these vaccines on carriage, standardized approaches to identify and group Nm are required. Real-time PCR (rt-PCR) capsule grouping assays that were internally controlled to confirm Nm species were developed for eight serogroups associated with carriage (A, B, C, E, W, X, Y and Z). The grouping scheme was validated using diverse bacterial species associated with carriage and then used to evaluate a collection of diverse Nm carriage isolates (n=234). A scheme that also included porA and ctrA probes was able to speciate the isolates, while ctrA also provided insights on the integrity of the polysaccharide loci. Isolates were typed for the Nm vaccine antigen factor H binding protein (fHbp), and were found to represent the known diversity of this antigen. The porA rt-PCR yielded positive results with all 234 of the Nm carriage isolates. Genogrouping assays classified 76.5% (179/234) of these isolates to a group, categorized 53 as nongenogroupable (NGG) and two as mixed results. Thirty seven NGG isolates evidenced a disrupted capsular polysaccharide operon judged by a ctrA negative result. Only 28.6% (67/234) of the isolates were serogrouped by slide agglutination (SASG), highlighting the reduced capability of carriage strains to express capsular polysaccharide. These rt-PCR assays provide a comprehensive means to identify and genogroup N. meningitidis in carriage studies used to guide vaccination strategies and to assess the impact of novel fHbp containing vaccines on meningococcal carriage.

No MeSH data available.


Distribution of the fHbp variants by genogroup in the carriage isolate collection.Carriage isolates were categorized by fHbp variant within each genogroup and are shown according to number of isolates identified. Blue bars, fHbp subfamily A variants; red bars, fHbp subfamily B variants. NGG, nongenogroupable by rt-PCR.
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pone.0132140.g003: Distribution of the fHbp variants by genogroup in the carriage isolate collection.Carriage isolates were categorized by fHbp variant within each genogroup and are shown according to number of isolates identified. Blue bars, fHbp subfamily A variants; red bars, fHbp subfamily B variants. NGG, nongenogroupable by rt-PCR.

Mentions: The carriage isolates were obtained from adolescents and young adults over a five-year period (1997–2001) that encompassed the introduction of NmC vaccines in the United Kingdom. The gene that encodes fHbp was detected in all 234 isolates. As has been reported in other Nm carriage collections [45,46], the majority of the isolates typed to fHbp subfamily A (185 or 79%). Fourteen fHbp variants, each identified in three or more isolates, together represented 88% of the isolates in the study (Fig 2). In this collection, a broader diversity of fHbp variant types were identified for genogroups B, C, E, and Z than for W, X, and Y, which were primarily composed of isolates carrying fHbp subfamily A variants (Fig 3). There were 21 different fHbp variants distributed among isolates genogrouped as NmB, with the most abundant being variant A22 (n = 22). NmW isolates were more homogeneous and predominantly A19 (n = 26). The distribution of variant B09 spanned genogroups B, E and NG, but was primarily found in isolates genogrouped as E (n = 14).


Optimization of Molecular Approaches to Genogroup Neisseria meningitidis Carriage Isolates and Implications for Monitoring the Impact of New Serogroup B Vaccines.

Rojas E, Hoyos J, Oldfield NJ, Lee P, Flint M, Jones CH, Ala'Aldeen DA, Jansen KU, Anderson AS - PLoS ONE (2015)

Distribution of the fHbp variants by genogroup in the carriage isolate collection.Carriage isolates were categorized by fHbp variant within each genogroup and are shown according to number of isolates identified. Blue bars, fHbp subfamily A variants; red bars, fHbp subfamily B variants. NGG, nongenogroupable by rt-PCR.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493136&req=5

pone.0132140.g003: Distribution of the fHbp variants by genogroup in the carriage isolate collection.Carriage isolates were categorized by fHbp variant within each genogroup and are shown according to number of isolates identified. Blue bars, fHbp subfamily A variants; red bars, fHbp subfamily B variants. NGG, nongenogroupable by rt-PCR.
Mentions: The carriage isolates were obtained from adolescents and young adults over a five-year period (1997–2001) that encompassed the introduction of NmC vaccines in the United Kingdom. The gene that encodes fHbp was detected in all 234 isolates. As has been reported in other Nm carriage collections [45,46], the majority of the isolates typed to fHbp subfamily A (185 or 79%). Fourteen fHbp variants, each identified in three or more isolates, together represented 88% of the isolates in the study (Fig 2). In this collection, a broader diversity of fHbp variant types were identified for genogroups B, C, E, and Z than for W, X, and Y, which were primarily composed of isolates carrying fHbp subfamily A variants (Fig 3). There were 21 different fHbp variants distributed among isolates genogrouped as NmB, with the most abundant being variant A22 (n = 22). NmW isolates were more homogeneous and predominantly A19 (n = 26). The distribution of variant B09 spanned genogroups B, E and NG, but was primarily found in isolates genogrouped as E (n = 14).

Bottom Line: Isolates were typed for the Nm vaccine antigen factor H binding protein (fHbp), and were found to represent the known diversity of this antigen.Thirty seven NGG isolates evidenced a disrupted capsular polysaccharide operon judged by a ctrA negative result.Only 28.6% (67/234) of the isolates were serogrouped by slide agglutination (SASG), highlighting the reduced capability of carriage strains to express capsular polysaccharide.

View Article: PubMed Central - PubMed

Affiliation: Vaccine Research and Development, Pfizer Inc, Pearl River, New York, United States of America.

ABSTRACT
The reservoir for Neisseria meningitidis (Nm) is the human oropharynx. Implementation of Nm serogroup C (NmC) glycoconjugate vaccines directly reduced NmC carriage. Prophylactic vaccines are now available to prevent disease caused by the five major Nm disease causing serogroups (ABCWY). Nm serogroup B (NmB) vaccines are composed of antigens that are conserved across Nm serogroups and therefore have the potential to impact all Nm carriage. To assess the effect of these vaccines on carriage, standardized approaches to identify and group Nm are required. Real-time PCR (rt-PCR) capsule grouping assays that were internally controlled to confirm Nm species were developed for eight serogroups associated with carriage (A, B, C, E, W, X, Y and Z). The grouping scheme was validated using diverse bacterial species associated with carriage and then used to evaluate a collection of diverse Nm carriage isolates (n=234). A scheme that also included porA and ctrA probes was able to speciate the isolates, while ctrA also provided insights on the integrity of the polysaccharide loci. Isolates were typed for the Nm vaccine antigen factor H binding protein (fHbp), and were found to represent the known diversity of this antigen. The porA rt-PCR yielded positive results with all 234 of the Nm carriage isolates. Genogrouping assays classified 76.5% (179/234) of these isolates to a group, categorized 53 as nongenogroupable (NGG) and two as mixed results. Thirty seven NGG isolates evidenced a disrupted capsular polysaccharide operon judged by a ctrA negative result. Only 28.6% (67/234) of the isolates were serogrouped by slide agglutination (SASG), highlighting the reduced capability of carriage strains to express capsular polysaccharide. These rt-PCR assays provide a comprehensive means to identify and genogroup N. meningitidis in carriage studies used to guide vaccination strategies and to assess the impact of novel fHbp containing vaccines on meningococcal carriage.

No MeSH data available.