Novel aspects of the Z and R3 antigens of streptococcus agalactiae revealed by immunological testing.
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Date
2013
Journal Title
Journal ISSN
Volume Title
Publisher
ASM: American Society for Microbiology
Abstract
Group B streptococci (GBS) are important human and bovine pathogens which can be classified by a variety of phenotype- and
gene-based techniques. The capsular polysaccharide and strain-variable, surface-anchored proteins are particularly important
phenotypic markers. In an earlier study, a previously unrecognized protein antigen called Z was described. It was expressed by
27.2% of GBS strains from Zimbabwe, usually in combination with R3 protein expression. In this study, a putative Z-specific
antiserum actually contained antibodies against two different antigens named Z1 and Z2; Z1 was>250 kDa in molecular mass.
Z1, Z2, and R3 generated multiple stained bands on Western blots and showed similar chromatographic characteristics with
respect to molecular mass, aggregate formation, and charge. Of 28 reference and prototype GBS strains examined, 8/28 (28.5%)
isolates expressed one, two, or all three of the Z1, Z2, and R3 antigens; 4/28 expressed all three antigens; 2/28 expressed Z2 and
R3; 1/28 expressed Z1 only; and 1/28 expressed R3 only. Twenty (71.5%) of the 28 isolates expressed none of the three antigens.
Expression of one or more of these antigens was shown by isolates of the capsular polysaccharide types Ia, Ib, V, and IX and NT
strains and occurred in combination with expression of various other strain-variable and surface-localized protein antigens.
When used as serosubtype markers, Z1, Z2, and R3 affected existing GBS serotype designations for some of the isolates. For instance,
the R3 reference strain Prague 10/84 (ATCC 49447) changed serotype markers from V/R3 to V/R3, Z1, and Z2. Other isolates
may change correspondingly, implying consequences for GBS serotyping and research.
Description
Keywords
Group B streptococci (GBS), GBS strains
Citation
Maeland, J. A., Radtke, A., Lyng, R. V., & Mavenyengwa, R. T. (2013). Novel aspects of the Z and R3 antigens of streptococcus agalactiae revealed by immunological testing. Clinical and Vaccine Immunology, 20(4), 607-612.