Murine whole-blood opsonophagocytosis assay to evaluate protection by antibodies raised against encapsulated extracellular bacteria

Abstract

In vaccine development, especially against pathogenic encapsulated extracellular bacteria, functional assays such as the opsonophagocytosis assay (OPA) are preferred to ELISA titers for evaluating protection against infection. Such assays are normally performed using phagocytic cell lines or purified cell types, which underestimate the complexity of blood bactericidal activity. Here, we describe an OPA using murine whole-blood as effector cells, in a small format (0.2 ml), which requires small quantities of sera (80 μl or less) from immunized individuals. Easy to develop and perform, this OPA can be readily adapted to various pathogens and could be used to evaluate sera from human or animal clinical trials of carbohydrate-based vaccines.