title: Development of a recombinant toxin fragment vaccine for Clostridium difficile infection.
abstract: Clostridium difficile infection (CDI) is the major cause of antibiotic-associated diarrhea and pseudomembranous colitis, a disease associated with significant morbidity and mortality. The disease is mostly of nosocomial origin, with elderly patients undergoing anti-microbial therapy being particularly at risk. C. difficile produces two large toxins: Toxin A (TcdA) and Toxin B (TcdB). The two toxins act synergistically to damage and impair the colonic epithelium, and are primarily responsible for the pathogenesis associated with CDI. The feasibility of toxin-based vaccination against C. difficile is being vigorously investigated. A vaccine based on formaldehyde-inactivated Toxin A and Toxin B (toxoids) was reported to be safe and immunogenic in healthy volunteers and is now undergoing evaluation in clinical efficacy trials. In order to eliminate cytotoxic effects, a chemical inactivation step must be included in the manufacturing process of this toxin-based vaccine. In addition, the large-scale production of highly toxic antigens could be a challenging and costly process. Vaccines based on non-toxic fragments of genetically engineered versions of the toxins alleviate most of these limitations. We have evaluated a vaccine assembled from two recombinant fragments of TcdB and explored their potential as components of a novel experimental vaccine against CDI. Golden Syrian hamsters vaccinated with recombinant fragments of TcdB combined with full length TcdA (Toxoid A) developed high titer IgG responses and potent neutralizing antibody titers. We also show here that the recombinant vaccine protected animals against lethal challenge with C. difficile spores, with efficacy equivalent to the toxoid vaccine. The development of a two-segment recombinant vaccine could provide several advantages over toxoid TcdA/TcdB such as improvements in manufacturability.
authors.affiliation: Merck Research Laboratories, Vaccine Basic Research, West Point, PA, United States. Electronic address: jerzy.karczewski@fhcmb.org.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Karczewski
authors.affiliation: Merck Research Laboratories, Vaccine Basic Research, West Point, PA, United States.
authors.forename: Julie
authors.initials: J
authors.lastname: Zorman
authors.affiliation: Merck Research Laboratories, Vaccine Basic Research, West Point, PA, United States.
authors.forename: Su
authors.initials: S
authors.lastname: Wang
authors.affiliation: Eurofins Laboratories, Lancaster, PA, United States.
authors.forename: Matthew
authors.initials: M
authors.lastname: Miezeiewski
authors.affiliation: Merck Research Laboratories, Vaccine Basic Research, West Point, PA, United States.
authors.forename: Jinfu
authors.initials: J
authors.lastname: Xie
authors.affiliation: Eurofins Laboratories, Lancaster, PA, United States.
authors.forename: Keri
authors.initials: K
authors.lastname: Soring
authors.affiliation: Merck Research Laboratories, Laboratory Animal Resources, West Point, PA, United States.
authors.forename: Ioan
authors.initials: I
authors.lastname: Petrescu
authors.affiliation: Merck Research Laboratories, Laboratory Animal Resources, West Point, PA, United States.
authors.forename: Irene
authors.initials: I
authors.lastname: Rogers
authors.affiliation: Merck Research Laboratories, Vaccine Drug Product Development, West Point, PA, United States.
authors.forename: David S
authors.initials: DS
authors.lastname: Thiriot
authors.affiliation: Merck Research Laboratories, Vaccine Basic Research, West Point, PA, United States.
authors.forename: James C
authors.initials: JC
authors.lastname: Cook
authors.affiliation: Agile 1, Torrance, CA, United States.
authors.forename: Mihaela
authors.initials: M
authors.lastname: Chamberlin
authors.affiliation: Merck Research Laboratories, Vaccine Basic Research, West Point, PA, United States.
authors.forename: Rachel F
authors.initials: RF
authors.lastname: Xoconostle
authors.affiliation: Merck Research Laboratories, Vaccine Basic Research, West Point, PA, United States.
authors.forename: Debbie D
authors.initials: DD
authors.lastname: Nahas
authors.affiliation: Merck Research Laboratories, Vaccine Basic Research, West Point, PA, United States.
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Joyce
authors.affiliation: Merck Research Laboratories, Vaccine Basic Research, West Point, PA, United States.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Bodmer
authors.affiliation: Merck Research Laboratories, Vaccine Basic Research, West Point, PA, United States.
authors.forename: Jon H
authors.initials: JH
authors.lastname: Heinrichs
authors.affiliation: Merck Research Laboratories, Vaccine Basic Research, West Point, PA, United States.
authors.forename: Susan
authors.initials: S
authors.lastname: Secore
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D057134:Antibodies, Neutralizing / Q000097:blood; D001426:Bacterial Proteins / Q000276:immunology*; D001427:Bacterial Toxins / Q000276:immunology*; D001428:Bacterial Vaccines / Q000276:immunology*; D016360:Clostridioides difficile; D003015:Clostridium Infections / Q000517:prevention & control*; D004761:Enterocolitis, Pseudomembranous / Q000517:prevention & control*; D004768:Enterotoxins / Q000276:immunology*; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D008647:Mesocricetus; D009500:Neutralization Tests; D011994:Recombinant Proteins / Q000276:immunology; D014614:Vaccines, Synthetic / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D057134:Antibodies, Neutralizing; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D001428:Bacterial Vaccines; D004768:Enterotoxins; D007074:Immunoglobulin G; D011994:Recombinant Proteins; D014614:Vaccines, Synthetic; C041348:tcdA protein, Clostridium difficile; C031815:toxB protein, Clostridium difficile
keywords: Clostridium difficile; Recombinant vaccine; TcdA; TcdB