Polysaccharide Vaccines: A Perspective on Non-Typhoidal Salmonella

Abstract

Polysaccharides are often the most abundant antigens found on the extracellular surfaces of bacterial cells. These polysaccharides play key roles in interactions with the outside world, and for many bacterial pathogens, they represent what is presented to the human immune system. As a result, many vaccines have been or currently are being developed against carbohydrate antigens. In this review, we explore the diversity of capsular polysaccharides (CPS) in Salmonella and other selected bacterial species and explain the classification and function of CPS as vaccine antigens. Despite many vaccines being developed using carbohydrate antigens, the low immunogenicity and the diversity of infecting strains and serovars present an antigen formulation challenge to manufacturers. Vaccines tend to focus on common serovars or have changing formulations over time, reflecting the trends in human infection, which can be costly and time-consuming. We summarize the approaches to generate carbohydrate-based vaccines for Salmonella, describe vaccines that are in development and emphasize the need for an effective vaccine against non-typhoidal Salmonella strains.

Meeting Summary: Global Vaccine and Immunization Research Forum, 2021

“…Other priority diseases. Clinical studies have been launched for multiple vaccines that target schistosomiasis [80] , [81] or invasive non-typhoidal salmonella [82] , [83] , [84] . Two typhoid conjugate vaccines have been pre-qualified by WHO [85] and programs using these vaccines are learning how to integrate them into broader disease control programs and conducting post-introduction effectiveness studies.…”

Phage-Derived Depolymerase: Its Possible Role for Secondary Bacterial Infections in COVID-19 Patients

“…One method of phage resistance is to produce polysaccharide-thick layers, such as capsules, slime, or biofilm matrix, to prevent virion adsorption to the bacterial surface [ 22 ]. Bacteria use capsular polysaccharides (CPS) to defend against viral infection [ 23 ]. However, some phages evolved a particular technique to overcome this obstacle.…”

Combinatorial multimer staining and spectral flow cytometry facilitate quantification and characterization of polysaccharide-specific B cell immunity

“…These carbohydrate chains portray extensive biochemical diversity coming from the constituting monosaccharides and their type of linkage, which results in distinct serotypes with varying antigenicity, immunogenicity and pathogenicity 1 . Serotype-specific PS are immunodominant antigens and commonly used as vaccine targets to induce protective B cell responses and neutralizing antibodies, as shown by current vaccines against S. pneumoniae (Spn or pneumococcus), Haemophilus influenzae type b, Neisseria meningitidis and Salmonella typhoid VI 2 .…”