Serum Bactericidal Assay with Luminescent Readout (L-SBA)

The Luminescence-SBA (L-SBA) applies to the same principles of the conventional SBA but evaluates the antibody bactericidal activity by quantifying the ATP level as a correlate of bacterial survival. In L-SBA the level of luminescence detected is directly proportional to the number of bacteria present in the assay wells, which is inversely proportional to the level of functional antibodies present in the serum. Therefore, serum bactericidal titer obtained by the luminescence readout method strongly correlates with the data obtained by the conventional agar plate-based assay. The luminescence readout overcomes the major limitations of the conventional SBA by enabling bactericidal titers to be calculated directly in a microplate-based format; for this reason, it can be used as a high-throughput functional assay to evaluate vaccine immunogenicity. In VisMederi, the assay is mainly used to assess immune responses against Salmonella enterica serovar Typhi, Enteriditis, Typhimurium and Paratyphi A, as well as Shigella Flexneri and Sonnei (Qualification of a high-throughput luminescence-based Serum Bactericidal Activity assay to assess the functionality of human sera against five Shigella serotypes.).

When appropriately validated and qualified this approach provides a rapid, sensitive, and high‑throughput alternative to conventional SBA as valuable evidence to support the clinical development and regulatory approval of bacterial vaccines.