A Possible Oligosaccharide-Conjugate Vaccine Candidate for Clostridium difficile Is Antigenic and Immunogenic

Abstract

Nosocomial infections with the Gram-positive pathogen Clostridium difficile pose a major risk for hospitalized patients and result in significant costs to health care systems. Here, we present the chemical synthesis of a PS-II hapten of a cell wall polysaccharide of hypervirulent ribotype 027 of C. difficile. Mice were immunized with a conjugate consisting of the synthetic hexasaccharide and the diphtheria toxoid variant CRM(197). The immunogenicity of the glycan repeating unit was demonstrated by the presence of specific IgG antibodies in the serum of immunized mice. Murine monoclonal antibodies interact with the synthetic hexasaccharide, as determined by microarray analysis. Finally, we found that specific IgA antibodies in the stool of hospital patients infected with C. difficile recognize the synthetic PS-II hexasaccharide hapten.

Vaccines againstClostridium difficile

“…142 The PSII polysaccharide conjugated to diphtheria toxoid CRM197 was tested in Balb/C mice formulated with adjuvant MF59, and elicited high levels of IgG. 139 Importantly, in the same study it was evidenced that one single repeating unit phosphorylated at the non-terminal sugar was able to reach IgG levels comparable to the polymer, and the charged phosphate group is critical to induce IgG antibodies able to recognize the entire native polysaccharide.…”

The potential for emerging therapeutic options forClostridium difficileinfection

“…135 Oberli et al chemically synthesized an oligosaccharide-conjugate vaccine composed of the PSII hapten of a C. difficile R027 strain. 136 The authors found that immunized mice displayed specific IgG antibodies in serum in response to the synthetic hexasaccharide and diphtheria toxoid variant CRM(197) conjugate vaccine. The IgG antibodies were mounted specifically against the glycan repeating subunit of the conjugate vaccine.…”

“…The IgG antibodies were mounted specifically against the glycan repeating subunit of the conjugate vaccine. 136 DNA-based and other types of vaccines Baliban et al investigated the effect of cloning the receptor binding domain (RBD) of TcdA and TcdB on protection against C. difficile and vaccination with such DNA sequences elicited high levels of anti-RBD antibodies in mouse models. 137 In another study, a gene which encoded the receptor binding domain of TcdA was synthesized and designed for expression in human cells.…”

Adaptive immune response to Clostridium difficile infection: A perspective for prevention and therapy

“…In particular, SLPs of C. difficile are not only responsible for adhesion to intestinal epithelial cells, but are also capable of inducing immune responses in CDI patients [47][48][49]. Because of this discovery, SLPs and other non-toxin proteins such as flagellin (FliC), flagellar cap protein (FliD), and cell wall protein (Cwps), in addition to oligosaccharides [50], lipoteichoic acids, and carbohydrate polymers (PS-II) [51] look to be promising antigens for vaccinations. Péchiné et al studied FliC, FliD and various Cwps for expression, variability, and serum antibody responses in 17 CDI patients.…”