10.6084/m9.figshare.7936868.v2
Areej Alhhazmi
Areej
Alhhazmi
Gregory J. Tyrrell
Gregory J.
Tyrrell
Phenotypic and molecular analysis of nontypeable Group B streptococci: identification of <i>cps2a</i> and hybrid <i>cps2a/cps5</i> Group B streptococcal capsule gene clusters
Taylor & Francis Group
2019
surface sialic acid
group b streptococcus
gene clusters identical
decreased camp activity
cpsv suggesting recombination
based typing assay
ten recognized cpss
third isolate possessed
dna sequence analysis
phenotypic traits assayed
assaying phenotypic changes
15 isolates assayed
uncommon cpsiia type
hybrid cluster containing
ten cps types
failed cps identification
gbs nt isolates
ten types
molecular analysis
gbs isolate
cps cannot
cps ).
cps </
two groups
sia (−))
sia (+)).
second objective
recently described
orange pigmentation
may potentially
immundiffusion antisera
human blood
form biofilm
first objective
considered nontypeable
capsular polysaccharide
altered phenotypes
2019-10-24 12:12:16
Dataset
https://tandf.figshare.com/articles/dataset/Phenotypic_and_molecular_analysis_of_nontypeable_Group_B_streptococci_identification_of_i_cps2a_i_and_hybrid_i_cps2a_cps5_i_Group_B_streptococcal_capsule_gene_clusters/7936868
<p>The Group B streptococcus (GBS) can express a capsular polysaccharide (CPS). There are ten recognized CPSs (Ia, Ib, and II–IX). A GBS isolate is considered nontypeable (NT) when CPS cannot be identified as one of ten types. Two groups of GBS NT isolates were studied, isolates without surface sialic acid (sia(−)) and isolates with surface sialic acid (sia(+)). The first objective was to characterize NT sia(−) isolates that failed CPS identification by an immunodiffusion antisera typing assay and a RT-PCR capsule typing assay. NT sia(−) isolates were characterized by assaying phenotypic changes and identifying <i>covR/S</i> mutations that may potentially have a role in the altered phenotypes. The second objective was to characterize NT sia(+) isolates that failed to identify as one of the ten CPS types by an immundiffusion antisera-based typing assay and a RT-PCR capsule typing assay yet expressed capsule. Fifteen NT sia(−) isolates displayed increased β hemolysis/orange pigmentation, decreased CAMP activity, inability to form biofilm, and susceptibility to phagocytosis by human blood. DNA sequence analysis of the <i>covR/S</i> genes in the sia(−) isolates found mutations in 14 of 15 isolates assayed. These mutations in the <i>covR/S</i> genes may potentially contribute to lack of expression of phenotypic traits assayed in vitro. For the three NT sia(+) isolates, whole-genome sequence analyses identified two isolates with <i>cps</i> gene clusters identical to the recently described and uncommon CPSIIa type. The third isolate possessed a hybrid cluster containing <i>cps</i> genes for both CPSIIa and CPSV suggesting recombination between these two gene clusters.</p>