Andrea Gori, United Kingdom
University College London Infection and ImmunityPresenter of 2 Presentations
THE EMERGENCE OF A STREPTOCOCCUS PNEUMONIAE SEROTYPE 3 VARIANT CARRIAGE IN THE 8 YEARS FOLLOWING POST-PCV13 INTRODUCTION IN BLANTYRE, MALAWI. (ID 606)
Abstract
Background
Several studies have demonstrated limited PCV13 efficacy against carriage of serotype 3 Streptococcus pneumoniae. In Blantyre, no direct vaccine effect was identified on serotype 3 carriage 8 years after PCV13 introduction, and population-based serology showed limited induction of serotype 3-specific antibodies by vaccine or natural exposure. We hypothesised that sequence variability of the CPS locus could at least partly explain these observations.
Methods
CPS loci of 540 serotype 3 isolates (from Africa, Asia, Europe and America) were analysed. ML-phylogeny, antimicrobial resistance (tetM, mefA, ermB, cat gene presence and pbpX allelic profiles) and MLST were calculated. Colony morphology was assessed in microaerophilic and anaerobic conditions.
Results
We identified a serotype 3 CPS locus variant in 82% of Blantyre isolates (2015-2019), characterized by an 8-gene cluster deletion but unchanged colony morphology. This variant appeared independently in at least 3 distinct phylogenetic clusters, including ST700 and ST3214. These strains are characterised by the presence of AMR genes and higher MIC to penicillin. The missing CPS genes have hypothetical protein annotation.
Conclusions
This CPS variant segregated with an AMR genotype, which may have contributed to its emergence. Whether this CPS variation will influence immunogenicity remains to be determined.
INCREASE IN FREQUENCY OF PNEUMOCOCCAL METABOLIC GENOTYPES CHARACTERISED BY ANTIMICROBIAL RESISTANCE AND ADAPTATIONS FOR COLONIZATION AFTER PCV13 INTRODUCTION IN BLANTYRE, MALAWI. (ID 416)
- Andrea Gori, United Kingdom
- Uri Obolski, Israel
- Todd D. Swarthout, Malawi
- Jose Lourenço, United Kingdom
- Caroline M. Weight, United Kingdom
- Jen Cornick,
- Dean Everett, Malawi
- Arox Kamng'ona,
- Thandie S. Mwalukomo,
- Martin C. Maiden, United Kingdom
- Neil French, United Kingdom
- Sunetra Gupta, United Kingdom
- Robert S. Heyderman, United Kingdom
Abstract
Background
Streptococcus pneumoniae naturally undergoes fluctuations in genotype. We previously showed a high residual prevalence of vaccine serotype (VT) pneumococci (18% in under 5’s) 7 years after PCV13 introduction in Malawi. In this context, we hypothesised the emergence and fixation of S. pneumoniae lineages with genetic traits conveying a competitive advantage in the nasopharyngeal niche.
Methods
1826 S. pneumoniae genomes were analysed from isolates collected during rolling cross-sectional carriage surveys in Blantyre, 4-7 years after PCV13 introduction. The metabolic core-genome includes 175 discrete metabolic genotypic profiles (metabolic types, MTs). Relative fitness was assessed by in-vitro growth and adhesive potential evaluated using Detroit 562 nasopharyngeal epithelial cells.
Results
High residual pneumococcal carriage is characterised by persistent MTs in VT (e.g. 3 and 23F) and emerging new MTs in non-VT (NVT; 38 and 23B). Increase in AMR MTs among 38 and 23B was observed. Emerging MTs show characteristic sequences of virulence genes and are characterised phenotypically by higher growth potential and propensity for better adherence to NP cell. We identified convergent evolution between MTs isolated in different countries, result of genetic bottlenecks.
Conclusions
This shift in metabolic genotypes, antimicrobial resistance and colonization adaptations may facilitate vaccine escape.
Author Of 4 Presentations
STREPTOCOCCUS PNEUMONIAE VACCINE SEROTYPES ACQUIRE PENICILLIN BINDING PROTEIN GENE MOSAICS FROM STREPTOCOCCUS MITIS (ID 428)
- Akuzike Kalizang'oma, United Kingdom
- Chrispin Chaguza, United Kingdom
- Andrea Gori, United Kingdom
- Charlotte Davison, United Kingdom
- Sandra Beleza, United Kingdom
- Martin Antonio, Gambia
- Bernard Beall, United States of America
- David Goldblatt, United Kingdom
- Brenda Kwambana-Adams, United Kingdom
- Stephen D. Bentley, United Kingdom
- Robert S. Heyderman, United Kingdom
THE EMERGENCE OF A STREPTOCOCCUS PNEUMONIAE SEROTYPE 3 VARIANT CARRIAGE IN THE 8 YEARS FOLLOWING POST-PCV13 INTRODUCTION IN BLANTYRE, MALAWI. (ID 606)
Abstract
Background
Several studies have demonstrated limited PCV13 efficacy against carriage of serotype 3 Streptococcus pneumoniae. In Blantyre, no direct vaccine effect was identified on serotype 3 carriage 8 years after PCV13 introduction, and population-based serology showed limited induction of serotype 3-specific antibodies by vaccine or natural exposure. We hypothesised that sequence variability of the CPS locus could at least partly explain these observations.
Methods
CPS loci of 540 serotype 3 isolates (from Africa, Asia, Europe and America) were analysed. ML-phylogeny, antimicrobial resistance (tetM, mefA, ermB, cat gene presence and pbpX allelic profiles) and MLST were calculated. Colony morphology was assessed in microaerophilic and anaerobic conditions.
Results
We identified a serotype 3 CPS locus variant in 82% of Blantyre isolates (2015-2019), characterized by an 8-gene cluster deletion but unchanged colony morphology. This variant appeared independently in at least 3 distinct phylogenetic clusters, including ST700 and ST3214. These strains are characterised by the presence of AMR genes and higher MIC to penicillin. The missing CPS genes have hypothetical protein annotation.
Conclusions
This CPS variant segregated with an AMR genotype, which may have contributed to its emergence. Whether this CPS variation will influence immunogenicity remains to be determined.
MODELLING POST-PCV13 SEROTYPE-SPECIFIC ANTI-CAPSULAR AND ANTI-PROTEIN IGG RESPONSES IN BLANTYRE, MALAWI. (ID 989)
- Jose Lourenço, United Kingdom
- Todd D. Swarthout, Malawi
- Mahan Ghafari,
- James Meiring, United Kingdom
- Andrea Gori, United Kingdom
- Uri Obolski, Israel
- Deus Thindwa, United Kingdom
- Comfort Brown, Malawi
- Maurice Mbewe, Malawi
- Melita Gordon, Malawi
- David Goldblatt, United Kingdom
- Neil French, United Kingdom
- Sunetra Gupta, United Kingdom
- Robert S. Heyderman, United Kingdom
INCREASE IN FREQUENCY OF PNEUMOCOCCAL METABOLIC GENOTYPES CHARACTERISED BY ANTIMICROBIAL RESISTANCE AND ADAPTATIONS FOR COLONIZATION AFTER PCV13 INTRODUCTION IN BLANTYRE, MALAWI. (ID 416)
- Andrea Gori, United Kingdom
- Uri Obolski, Israel
- Todd D. Swarthout, Malawi
- Jose Lourenço, United Kingdom
- Caroline M. Weight, United Kingdom
- Jen Cornick,
- Dean Everett, Malawi
- Arox Kamng'ona,
- Thandie S. Mwalukomo,
- Martin C. Maiden, United Kingdom
- Neil French, United Kingdom
- Sunetra Gupta, United Kingdom
- Robert S. Heyderman, United Kingdom
Abstract
Background
Streptococcus pneumoniae naturally undergoes fluctuations in genotype. We previously showed a high residual prevalence of vaccine serotype (VT) pneumococci (18% in under 5’s) 7 years after PCV13 introduction in Malawi. In this context, we hypothesised the emergence and fixation of S. pneumoniae lineages with genetic traits conveying a competitive advantage in the nasopharyngeal niche.
Methods
1826 S. pneumoniae genomes were analysed from isolates collected during rolling cross-sectional carriage surveys in Blantyre, 4-7 years after PCV13 introduction. The metabolic core-genome includes 175 discrete metabolic genotypic profiles (metabolic types, MTs). Relative fitness was assessed by in-vitro growth and adhesive potential evaluated using Detroit 562 nasopharyngeal epithelial cells.
Results
High residual pneumococcal carriage is characterised by persistent MTs in VT (e.g. 3 and 23F) and emerging new MTs in non-VT (NVT; 38 and 23B). Increase in AMR MTs among 38 and 23B was observed. Emerging MTs show characteristic sequences of virulence genes and are characterised phenotypically by higher growth potential and propensity for better adherence to NP cell. We identified convergent evolution between MTs isolated in different countries, result of genetic bottlenecks.
Conclusions
This shift in metabolic genotypes, antimicrobial resistance and colonization adaptations may facilitate vaccine escape.