Vi polysaccharide and conjugated vaccines afford similar early, IgM or IgG-independent control of infection but boosting with conjugated Vi vaccines sustains the efficacy of immune responses

• DOI: 10.1101/2023.01.03.522561
• Publication Date: 2023-01-05T10:27:21Z
• Authors: Siân E. Jossi; Melissa Arcuri; Areej Alshayea; Ruby R. Persaud; Edith Marcial-Juárez; Elena Palmieri; Roberta Di Benedetto; Marisol Pérez-Toledo; Jamie Pillaye; Will M. Channell; Anna E. Schager; Rachel E. Lamerton; Charlotte N. Cook; Margaret Goodall; Takeshi Haneda; Andreas J. Bäumler; Lucy H. Jackson-J...; Kai-Michael Toellner; Calman A. MacLennan; Ian R. Henderson; Francesca Micoli; Adam F. Cunningham
• Keywords: Toxoid; Diphtheria Toxin

Abstract Vaccination with Vi capsular polysaccharide (Vi-PS) or protein-Vi typhoid conjugate vaccine (TCV) can protect adults against Salmonella Typhi infections. TCVs offer better protection than Vi-PS in infants and may adults. Potential reasons for why TCV be superior are not fully understood. Here, we immunized wild-type (WT) mice deficient IgG IgM (Vi conjugated to tetanus toxoid CRM 197 ) up seven months, without subsequent challenge Vi-expressing Typhimurium. Unexpectedly, alone were similarly able reduce bacterial burdens tissues, this was observed response unconjugated vaccines independent of antibody being high affinity. Only the longer-term after immunization (>5 months) differences tissue TCV. These related maintenance responses at higher levels boosted TCV, rate fall titres induced greater Therefore, Vi-specific independently capable protecting from infection any vaccination relate persist rather isotypes induced. findings suggest that enhancing our understanding how maintained inform on maximize afforded by encapsulated pathogens such as S . Typhi.