Biochemical and immunological evaluation of recombinant CS6-derived subunit enterotoxigenic Escherichia coli vaccine candidates
JournalInfection and Immunity
PublisherAmerican Society for Microbiology
MetadataShow full item record
AbstractCS6, a prevalent surface antigen expressed in nearly 20% of clinical enterotoxigenic Escherichia coli (ETEC) isolates, is comprised of two major subunit proteins, CssA and CssB. Using donor strand complementation, we constructed a panel of recombinant proteins of 1 to 3 subunits that contained combinations of CssA and/or CssB subunits and a donor strand, a C-terminal extension of 16 amino acids that was derived from the N terminus of either CssA or CssB. While the entire panel of recombinant proteins could be obtained as soluble, folded proteins, it was observed that the proteins possessing a heterologous donor strand, derived from the CS6 subunit different from the C-terminal subunit, had the highest degree of physical and thermal stability. Immunological characterization of the proteins, using a murine model, demonstrated that robust anti-CS6 immune responses were generated from fusions containing both CssA and CssB. Proteins containing only CssA were weakly immunogenic. Heterodimers, i.e., CssBA and CssAB, were sufficient to recapitulate the anti-CS6 immune response elicited by immunization with CS6, including the generation of functional neutralizing antibodies, as no further enhancement of the response was obtained with the addition of a third CS6 subunit. Our findings here demonstrate the feasibility of including a recombinant CS6 subunit protein in a subunit vaccine strategy against ETEC. Copyright 2019 American Society for Microbiology. All Rights Reserved.
SponsorsWe thank the Walter Reed Army Institute of Research for the provision of recombinant CS6. Additionally, we are thankful for the technical support from Glomil Corbin, William Hulsey, Diana Zhang, Patrick Bonifassi, and Laurence Fourrichon. We also acknowledge Julianne Rollenhagen for her assistance in reviewing the manuscript and Claudia Costabile for her assistance with image formatting. This research was supported by U.S. Army Military Infectious Diseases Research Program Work Unit no. U.S. Navy 6000.RAD1.DA2.A0307, the Henry M. Jackson Foundation for the Advancement of Military Medicine, and Sanofi Pasteur (NCRADA-NMR-09-3183). The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense, or the U.S. Government. S.J.S. and M.G.P. served as military service members over the course of this work, which was prepared as part of their official duties. Title 17 USC §105 provides that “copyright protection under this title is not available for any work of the United States Government.” Title 17 USC §101 defines a U.S. Government work as a work prepared by a military service member or employee of the U.S. Government as part of that person’s official duties. P.D. and G.R-M. are employees of Sanofi Pasteur. S.J.S. served as the principal investigator for the NMRC and USUHS at the time of the study and is now an employee of Sanofi Pasteur. All other authors declare that there are no financial, institutional, or other relationships that might lead to bias or a conflict of interest.
Identifier to cite or link to this itemhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-85061984026&doi=10.1128%2fIAI.00788-18&partnerID=40&md5=17f88f1f330b974d0712ec8897eee7a9; http://hdl.handle.net/10713/8673
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