title: Igg Subclasses Targeting the Flagella ofSalmonella entericaSerovar Typhimurium Can Mediate Phagocytosis and Bacterial Killing.
abstract: Invasive non-typhoidalSalmonellaare a common cause of invasive disease in immuno-compromised individuals and in children. Multi-drug resistance poses challenges to disease control, with a critical need for effective vaccines. Flagellin is an attractive vaccine candidate due to surface exposure and high epitope copy number, but its potential as a target for opsonophacytic antibodies is unclear. We examined the effect of targeting flagella with different classes of IgG on the interaction betweenSalmonellaTyphimurium and a human phagocyte-like cell line, THP-1. We tagged the FliC flagellar protein with a foreign CD52 mimotope (TSSPSAD) and bacteria were opsonized with a panel of humanised CD52 antibodies with the same antigen-binding V-region, but different constant regions. We found that IgG binding to flagella increases bacterial phagocytosis and reduces viable intracellular bacterial numbers. Opsonisation with IgG3, followed by IgG1, IgG4, and IgG2, resulted in the highest level of bacterial uptake and in the highest reduction in the intracellular load of viable bacteria. Taken together, our data provide proof-of-principle evidence that targeting flagella with antibodies can increase the antibacterial function of host cells, with IgG3 being the most potent subclass. These data will assist the rational design of urgently needed, optimised vaccines against iNTS disease.
authors.affiliation: Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, United Kingdom.
authors.forename: Yun Shan
authors.initials: YS
authors.lastname: Goh
authors.affiliation: Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, United Kingdom.
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Armour
authors.affiliation: Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, United Kingdom.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Clark
authors.affiliation: Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, United Kingdom.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Grant
authors.affiliation: Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, United Kingdom.
authors.forename: Pietro
authors.initials: P
authors.lastname: Mastroeni
keywords: Antibody; Flagella; IgG subclasses; Opsonisation; Phagocytosis