Functional assays to evaluate antibody-mediated responses against Shigella : a review

• Published in: Frontiers in cellular and infection microbiology Vol. 13; p. 1171213
• Main Authors: Boero, Elena, Vezzani, Giacomo, Micoli, Francesca, Pizza, Mariagrazia, Rossi, Omar
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 16.05.2023
• Subjects: antibodies; Cellular and Infection Microbiology; functional assays; invasion; opsonophagocytic killing assay (OPKA); serum bactericidal assay (SBA); Shigella; functional assays; serum bactericidal assay (SBA); antibodies; invasion; Shigella; opsonophagocytic killing assay (OPKA)
• ISSN: 2235-2988; 2235-2988
• DOI: 10.3389/fcimb.2023.1171213

is a major global pathogen and the etiological agent of shigellosis, a diarrheal disease that primarily affects low- and middle-income countries. Shigellosis is characterized by a complex, multistep pathogenesis during which bacteria use multiple invasion proteins to manipulate and invade the intestinal epithelium. Antibodies, especially against the O-antigen and some invasion proteins, play a protective role as titres against specific antigens inversely correlate with disease severity; however, the context of antibody action during pathogenesis remains to be elucidated, especially with being mostly an intracellular pathogen. In the absence of a correlate of protection, functional assays rebuilding salient moments of pathogenesis can improve our understanding of the role of protective antibodies in blocking infection and disease. assays are important tools to build correlates of protection. Only recently animal models to recapitulate human pathogenesis, often not in full, have been established. This review aims to discuss assays to evaluate the functionality of anti- antibodies in polyclonal sera in light of the multistep and multifaced infection process. Indeed, measurement of antibody level alone may limit the evaluation of full vaccine potential. Serum bactericidal assay (SBA), and other functional assays such as opsonophagocytic killing assays (OPKA), and adhesion/invasion inhibition assays (AIA), are instead physiologically relevant and may provide important information regarding the role played by these effector mechanisms in protective immunity. Ultimately, the review aims at providing scientists in the field with new points of view regarding the significance of functional assays of choice which may be more representative of immune-mediated protection mechanisms.