Vaccine. 2016 Apr 28. pii: S0264-410X(16)30229-8. doi: 10.1016/j.vaccine.2016.04.064. [Epub ahead of print]

Vaccine escape of piliated Streptococcus pneumoniae strains.

Regev-Yochay G1, Jaber H2, Hamdan A3, Daana M4, Nammouz H5, Thalji A6, Jaar F7, Abdeen Z8, Rubin C9, Huppert A8, Raz M5, Rahav G2; PICR study group.

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Abstract

INTRODUCTION:

Type1-pilus proteins were suggested as targets of future protein-based vaccines. Here we studied the effect of pneumococcal-conjugate vaccine (PCV7) implementation on the prevalence of piliated strains in a unique study setting which controls for typical confounders; the Palestinian-Israeli Collaborative Research (PICR).

METHODS:

Annual cross-sectional surveys of pneumococcal carriage were performed during 2009-2011 among two closely related population that live under different health policies (a) Palestinian-Authority (PA) (n=1773), where PCV7 was not yet introduced (b) East-Jerusalem (EJ) (n=983) where PCV7 was rapidly implemented. Clinical data were collected, pneumococci identified and characterized and the presence of Type1-pilus genes was determined by rrgC PCR.

RESULTS:

Following PCV7 implementation in EJ, overall carriage prevalence did not change (∼30%), but VT7 strains decreased from 61.5% to 33.8%. While prevalence of non-piliated-VT7 isolates decreased from 37% to 10%, p<0.001, the prevalence of piliated-VT7 strains persisted ∼25%. Additionally, piliated non-VT13 strains emerged (1-15%, p<0.001). These changes were not observed in PA. These dynamics were independent of the bacteria's resistance pattern.

CONCLUSIONS:

A differential effect of PCV7 was observed with a relative resistance of piliated strains to the vaccine. This suggests that Type1-pilus confers an intrinsic advantage for colonization and may be an attractive vaccine target.

Copyright © 2016. Published by Elsevier Ltd.

KEYWORDS:

PCV7 effects; Pilus type-1; Pneumococcal vaccines; Population-based study

PMID: 27133876 [PubMed - as supplied by publisher]