title: Recombinant antigens based on toxins A and B of Clostridium difficile that evoke a potent toxin-neutralising immune response.
abstract: Infection with the bacterium Clostridium difficile causes symptoms ranging from mild to severe diarrhoea with life-threatening complications and remains a significant burden to healthcare systems throughout the developed world. Two potent cytotoxins, TcdA and TcdB are the prime mediators of the syndrome and rapid neutralisation of these would afford significant benefits in disease management. In the present study, a broad range of non-toxic, recombinant fragments derived from TcdA and TcdB were designed for soluble expression in E. coli and assessed for their capacity to generate a potent toxin-neutralising immune response as assessed by cell-based assays. Significant differences between the efficacies of isolated TcdA and TcdB regions with respect to inducing a neutralising immune response were observed. While the C-terminal repeat regions played the principal role in generating neutralising antibodies to TcdA, in the case of TcdB, the central region domains dominated the neutralising immune response. For both TcdA and TcdB, fragments which comprised domains from both the central and C-terminal repeat region of the toxins were found to induce the most potent neutralising immune responses. Generated antibodies neutralised toxins produced by a range of C. difficile isolates including ribotype 027 and 078 strains. Passive immunisation of hamsters with a combination of antibodies to TcdA and TcdB fragments afforded complete protection from severe CDI induced by a challenge of bacterial spores. The results of the study are discussed with respect to the development of a cost effective immunotherapeutic approach for the management of C. difficile infection.
authors.affiliation: Public Health England, Porton Down, Salisbury, Wiltshire SP4 0JG, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Maynard-Smith
authors.affiliation: Public Health England, Porton Down, Salisbury, Wiltshire SP4 0JG, UK.
authors.forename: Helen
authors.initials: H
authors.lastname: Ahern
authors.affiliation: Public Health England, Porton Down, Salisbury, Wiltshire SP4 0JG, UK.
authors.forename: Joanna
authors.initials: J
authors.lastname: McGlashan
authors.affiliation: Public Health England, Porton Down, Salisbury, Wiltshire SP4 0JG, UK.
authors.forename: Philip
authors.initials: P
authors.lastname: Nugent
authors.affiliation: Public Health England, Porton Down, Salisbury, Wiltshire SP4 0JG, UK.
authors.forename: Roger
authors.initials: R
authors.lastname: Ling
authors.affiliation: Public Health England, Porton Down, Salisbury, Wiltshire SP4 0JG, UK.
authors.forename: Harriet
authors.initials: H
authors.lastname: Denton
authors.affiliation: MicroPharm Ltd, Station Road Industrial Estate, Newcastle Emlyn, Carmarthenshire SA38 9BY, UK.
authors.forename: Ruth
authors.initials: R
authors.lastname: Coxon
authors.affiliation: MicroPharm Ltd, Station Road Industrial Estate, Newcastle Emlyn, Carmarthenshire SA38 9BY, UK.
authors.forename: John
authors.initials: J
authors.lastname: Landon
authors.affiliation: Public Health England, Porton Down, Salisbury, Wiltshire SP4 0JG, UK.
authors.forename: April
authors.initials: A
authors.lastname: Roberts
authors.affiliation: Public Health England, Porton Down, Salisbury, Wiltshire SP4 0JG, UK. Electronic address: cliff.shone@phe.gov.uk.
authors.forename: Clifford
authors.initials: C
authors.lastname: Shone
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology*; D057134:Antibodies, Neutralizing / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology*; D001427:Bacterial Toxins / Q000276:immunology*; D002522:Chlorocebus aethiops; D016360:Clostridioides difficile; D006224:Cricetinae; D004768:Enterotoxins / Q000276:immunology*; D004926:Escherichia coli / Q000378:metabolism; D007106:Immune Sera / Q000276:immunology; D007116:Immunization, Passive; D011994:Recombinant Proteins / Q000276:immunology; D012756:Sheep; D014709:Vero Cells
chemical_list: D000907:Antibodies, Bacterial; D057134:Antibodies, Neutralizing; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004768:Enterotoxins; D007106:Immune Sera; D011994:Recombinant Proteins; C041348:tcdA protein, Clostridium difficile; C031815:toxB protein, Clostridium difficile
keywords: Difficile; Immunotherapy; Infection; Recombinant; Toxins; Vaccine