Vaccination against Salmonella Infection: the Mucosal Way

Abstract

subspecies includes several serovars infecting both humans and other animals and leading to typhoid fever or gastroenteritis. The high prevalence of associated morbidity and mortality, together with an increased emergence of multidrug-resistant strains, is a current global health issue that has prompted the development of vaccination strategies that confer protection against most serovars. Currently available systemic vaccine approaches have major limitations, including a reduced effectiveness in young children and a lack of cross-protection among different strains. Having studied host-pathogen interactions, microbiologists and immunologists argue in favor of topical gastrointestinal administration for improvement in vaccine efficacy. Here, recent advances in this field are summarized, including mechanisms of bacterial uptake at the intestinal epithelium, the assessment of protective host immunity, and improved animal models that closely mimic infection in humans. The pros and cons of existing vaccines are presented, along with recent progress made with novel formulations. Finally, new candidate antigens and their relevance in the refined design of anti- vaccines are discussed, along with antigen vectorization strategies such as nanoparticles or secretory immunoglobulins, with a focus on potentiating mucosal vaccine efficacy.

A Long-Term Efficacy Trial of a Live, Attenuated Salmonella Typhimurium Vaccine in Layer Hens

“…Further research is required to investigate uptake of ST1 vaccine from the lumen in avian GALT. Given the importance of the local gut immune response, focus on developing vaccines that are effective at producing a strong mucosal response ( Gayet et al, 2017 ) may be the key to reducing Salmonella colonization of the intestine and subsequent shedding in feces. In this study, hens were euthanized at the end of the trial and further studies are required to study secretory IgA response in the gut of vaccinated and vaccinated challenged birds, euthanized at periodic intervals after infection.…”

A Systematic Review: The Role of Resident Memory T Cells in Infectious Diseases and Their Relevance for Vaccine Development

“…is a group of Gram-negative bacilli that is a common cause of gastrointestinal infections responsible for “food poisoning.” Transmitted orally, this heterogeneous group of bacteria contains typhoid or enteric-fever causing serovars that can be potentially fatal to humans ( 170 ). Current vaccines against Salmonella are poorly immunogenic and risk disease in immunocompromised individuals ( 171 ). An effective vaccine that prevents gastrointestinal infection is much needed to prevent outbreaks of salmonellosis.…”

Salmonella Virulence and Immune Escape

“…However, the presence of host AMPs activates the PbgA which is required to maintain PhoPQ system of S. Typhimurium, promoting remodeling of outer membrane and resistance to innate immune AMPs [157]. The transcytosis of Salmonella across the gut epithelium by M cells is important for the induction of efficient immune responses to mucosal antigens in the Peyer's patches [158]. M cells function as the antigen-sampling cells, selectively transporting Salmonella antigens and delivering the latter to the underlying lymphoid tissues where protective immune responses are initiated [22,159].…”