E-Poster with pre-recorded video presentation Lorne Infection and Immunity 2021

Developing a high-throughput multiplex immunoassay that characterises antibody responses to StrepA vaccine antigens (#201)

Alana L Whitcombe 1 , Danilo Gomes Moriel 2 , Thomas Proft 1 , Nicole J Moreland 1
  1. School of Medical Sciences and Maurice Wilkins Centre, University of Auckland, Auckland, New Zealand
  2. GSK Vaccines Institute for Global Health, Sienna, Italy

Streptococcus pyogenes (StrepA) is an important human pathogen that causes illness ranging from mild skin and throat infections, to life-threatening invasive disease. Untreated StrepA infections can also lead to the autoimmune sequelae acute rheumatic fever (ARF), which can progress to permanent heart damage. Globally, these diseases cause significant morbidity and mortality and despite years of research, there is still no vaccine available to prevent StrepA disease. Several vaccines that target conserved antigens are currently in the early stages of development. Measuring antibodies specific to these antigens at a population level is essential to understanding immune status and establishing correlates of protection. The technology to do this for StrepA has been limited however, and rapid and sensitive assays for measuring serum antibody levels are needed. We have consequently developed a multiplex bead-based immunoassay that can detect and quantify antibody responses to leading StrepA vaccine antigens. This builds on our existing triplex assay whereby antigens used in clinical serology (SLO, DNase B and SpnA) together with five additional vaccine antigens (C5a Peptidase, Spy_0843, SpyCEP, SpyAD and the Group A carbohydrate), have been coupled to spectrally unique beads to form an 8-plex antigen panel. The assay has been optimised so that a broad range of antibody titres can be quickly and efficiently determined from a single serum dilution. Validation studies using human sera are now underway. This assay will be a powerful tool for measuring the prevalence of antibodies in patients with StrepA disease. In doing so, we can profile the natural immune response in high-risk populations to inform vaccine coverage.