Towards Development of a Non-Toxigenic Clostridioides difficile Oral Spore Vaccine against Toxigenic C. difficile

Abstract

Clostridioides difficile is an opportunistic gut pathogen which causes severe colitis, leading to significant morbidity and mortality due to its toxins, TcdA and TcdB. Two intra-muscular toxoid vaccines entered Phase III trials and strongly induced toxin-neutralising antibodies systemically but failed to provide local protection in the colon from primary C. difficile infection (CDI). Alternatively, by immunising orally, the ileum (main immune inductive site) can be directly targeted to confer protection in the large intestine. The gut commensal, non-toxigenic C. difficile (NTCD) was previously tested in animal models as an oral vaccine for natural delivery of an engineered toxin chimera to the small intestine and successfully induced toxin-neutralising antibodies. We investigated whether NTCD could be further exploited to induce antibodies that block the adherence of C. difficile to epithelial cells to target the first stage of pathogenesis. In NTCD strain T7, the colonisation factor, CD0873, and a domain of TcdB were overexpressed. Following oral immunisation of hamsters with spores of recombinant strain, T7-0873 or T7-TcdB, intestinal and systemic responses were investigated. Vaccination with T7-0873 successfully induced intestinal antibodies that significantly reduced adhesion of toxigenic C. difficile to Caco-2 cells, and these responses were mirrored in sera. Additional engineering of NTCD is now warranted to further develop this vaccine.

Characterisation of the butyrate production pathway in probiotic MIYAIRI588 by a combined whole genome-proteome approach

“…DNA was extracted from 10 mL culture grown to A 600nm 0.6 and Illumina sequencing performed as described by Hughes et al ., (2021) (34). For PacBio sequencing, a DNA library was prepared following the Pacific Biosciences Procedure & Checklist – Preparing whole genome and metagenome libraries using SMRTbell© prep kit 3.0.…”

Non-Toxin-Based Clostridioides difficile Vaccination Approaches

“…Moreover, hamsters immunized in the same way were partially protected from the lethal effects of CD toxins [ 59 ]. A NtTCD strain T7 was used as a vaccine platform to overexpress a colonization factor CD0873 and a domain of TcdB, whose spores were then administered to hamsters orally [ 60 ]. T7 with overexpressed CD0873 colonization factor effectively induced specific intestinal antibodies, which lowered the adhesion of pathogenic CD to Caco-2 cells.…”

Mucosal Vaccination Strategies against Clostridioides difficile Infection

“…Building off of our work on NTCD-based vaccines, another group sought to develop a modified NTCD vaccine that placed special emphasis on neutralizing colonization factors to block early pathogenesis [ 143 ]. The NTCD strain T7 was modified to express the colonization factor CD0873 and a domain of TcdB.…”

“…Likewise, a recombinant protein vaccine using the TcdB RBD offered full protection in an earlier study [ 37 ]. Oral administration of modified T7 spores in hamsters triggered a strong systemic and intestinal immune response, as measured by IgG and IgA levels [ 143 ]. Antibodies recovered from intestinal fluid and sera significantly reduced the adhesion of toxigenic C. difficile to Caco-2 cells [ 143 ].…”

“…Oral administration of modified T7 spores in hamsters triggered a strong systemic and intestinal immune response, as measured by IgG and IgA levels [ 143 ]. Antibodies recovered from intestinal fluid and sera significantly reduced the adhesion of toxigenic C. difficile to Caco-2 cells [ 143 ]. Since our research group also demonstrated that oral vaccination of hamsters with an unmodified NTCD strain (CCUG37785) also offered near-complete protection from CDI while also reducing spore shedding [ 144 ], this raises the opportunity for future studies to compare the effectiveness of NTCD vaccines that express recombinant antigens versus those that do not.…”