Figure 1. Determination of immunological end points that correlate with vaccine efficacy.

Standard assays for the determination of immune markers include those that measure humoral immunity, such as in vitro virus neutralization, ELISA (enzyme-linked immunosorbent assay) and EIA (enzyme immunoassay) (a), and others that measure cell-mediated responses, including antigen-stimulated proliferation or cytolytic activity. Correlates can also be sought in additional phenotypic (b) and functional immune markers (c) that associate with vaccine efficacy. T cell lineage markers, cytokine secretion, antibody class and effector functions can individually, or in combination, segregate with host survival outcome. Grz, granzyme; IFN, interferon; Ig, immunoglobulin; IL, interleukin; NK, natural killer; T_CM, T cell memory; T_E, T cell terminal effector; T_EM, T cell effector memory; T_H, T helper; TNF, tumour necrosis factor.