Modification of the classical Lancefield assay of group A streptococcal killing to reduce inter-donor variation

• Published in: Journal of microbiological methods 2016-05, Vol.124, p.69-71
• Main Authors: Reglinski, Mark, Lynskey, Nicola N., Sriskandan, Shiranee
• Format: Article
• Language: English
• Subjects: Antibodies, Bacterial - blood; Antibodies, Bacterial - immunology; Bacterial Proteins - immunology; Group A streptococcus; Humans; Immunoassay - methods; Lancefield assay; Streptococcal Infections - blood; Streptococcal Infections - immunology; Streptococcal Infections - microbiology; Streptococcus pyogenes; Streptococcus pyogenes - enzymology; Streptococcus pyogenes - growth & development; Streptococcus pyogenes - immunology; Surrogate of immunity
• ISSN: 0167-7012; 1872-8359
• DOI: 10.1016/j.mimet.2016.03.015

The lack of a surrogate-of-immunity assay presents a major barrier to Streptococcus pyogenes research. Modification of the Lancefield assay to include an antibody digestion step reduced inter-donor variation and permitted detection of the anti-streptococcal activity of intravenous immunoglobulin and convalescent serum, thus facilitating retrospective evaluation of immunity using stored samples. •The lack of a surrogate-of-immunity assay is a major barrier to S. pyogenes research.•Pre-treatment of whole blood with IdeS standardised bacterial growth between donors.•IdeS was subsequently inhibited using a non-cytotoxic iodoacetamide derivative.•The bactericidal action of stored samples could then be measured by Lancefield assay.•The modified assay facilitates retrospective dissection of anti-S. pyogenes immunity.