Streptococcus pneumoniae serotype 9A isolates contain diverse mutations to wcjE that result in variable expression of serotype 9V-specific epitope.

ABSTRACT: Streptococcus pneumoniae is a significant pathogen capable of expressing protective and antigenically diverse capsules. To better understand the molecular basis of capsular antigenic diversity, we investigated the hypothetical serological role of wcjE, which encodes a capsule O-acetyltransferase, in the vaccine-targeted serotype 9V and related serotype 9A.We inactivated wcjE by recombination in a serotype 9V strain and determined wcjE sequences of 11 serotype 9A clinical isolates. We determined the antigenic phenotypes of these pneumococcal strains with serogroup 9-specific antibodies and flow cytometry.Inactivation of wcjE in a serotype 9V strain resulted in expression of the 9A phenotype. Each serotype 9A clinical isolate contained a distinct mutation to wcjE. Flow cytometry showed that some 9A isolates (herein named 9A?) expressed trace amounts of 9V-specific epitopes whereas others (named 9A?) did not express any. Recombination with 9A? wcjE alleles into a 9A? strain conferred partial expression of 9V-specific epitopes.Each serotype 9A strain independently arose from a serotype 9V strain. Furthermore, clinical isolates identified as 9A can contain mutations to wcjE that are either partially functional or completely nonfunctional, demonstrating a previously unidentified antigenic heterogeneity of serotype 9A isolates.

SUBMITTER: Calix JJ 

PROVIDER: S-EPMC3222105 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature