Whole Cell ELISA Assay

The whole cell enzyme‑linked immunosorbent assay (whole cell ELISA) is an immunological binding assay used to measure serum antibody responses directed against surface antigens expressed on intact bacterial cells. In this assay, fixed or inactivated whole bacteria are immobilized onto microplate wells and incubated with serial dilutions of serum samples, allowing antigen‑specific antibodies to bind native surface epitopes in their conformational context. Bound antibodies are detected using enzyme‑conjugated secondary antibodies and an appropriate chromogenic substrate, with signal intensity proportional to the level of antibody binding. Antibody titers are typically reported as endpoint titers or as relative units based on predefined optical density thresholds. VisMederi commonly uses Whole cell ELISA in vaccine development and immunogenicity studies for pathogens such as Salmonella enterica serovar Enteriditis, serovar Typhi, serovar Typhimurium and Streptococcus pneumoniae. The method is generally viewed within EMA‑aligned regulatory frameworks as a supportive assay for measuring antibody binding responses, particularly when used alongside functional assays such as OPA or toxin neutralization assays.