James Meiring, United Kingdom

Oxford Vaccine Group Department of Paediatrics

Author Of 3 Presentations

 Conference Calendar

RAPID WANING OF VACCINE-INDUCED IMMUNITY AMONG PCV13-VACCINATED CHILDREN UNDER 5 YEARS OLD IN MALAWI WITH SUBSEQUENT ACQUISITION OF NATURAL ANTIBODY THROUGH NATURAL EXPOSURE (ID 267)

Session Name
Basic Sciences - Immunology, Pathogenesis, and Host-pathogen Interactions
Presenter
Authors

MODELLING POST-PCV13 SEROTYPE-SPECIFIC ANTI-CAPSULAR AND ANTI-PROTEIN IGG RESPONSES IN BLANTYRE, MALAWI. (ID 989)

Session Name
Population Sciences - Epidemiology, Economics, and Mathematical Modelling
Presenter
Authors

THE EMERGENCE OF A STREPTOCOCCUS PNEUMONIAE SEROTYPE 3 VARIANT CARRIAGE IN THE 8 YEARS FOLLOWING POST-PCV13 INTRODUCTION IN BLANTYRE, MALAWI. (ID 606)

Session Name
Basic Sciences - Genomics and Transmission
Presenter
Authors

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.

Hide