title: Novel Ricin Subunit Antigens With Enhanced Capacity to Elicit Toxin-Neutralizing Antibody Responses in Mice.
abstract: RiVax is a candidate ricin toxin subunit vaccine antigen that has proven to be safe in human phase I clinical trials. In this study, we introduced double and triple cavity-filling point mutations into the RiVax antigen with the expectation that stability-enhancing modifications would have a beneficial effect on overall immunogenicity of the recombinant proteins. We demonstrate that 2 RiVax triple mutant derivatives, RB (V81L/C171L/V204I) and RC (V81I/C171L/V204I), when adsorbed to aluminum salts adjuvant and tested in a mouse prime-boost-boost regimen were 5- to 10-fold more effective than RiVax at eliciting toxin-neutralizing serum IgG antibody titers. Increased toxin neutralizing antibody values and seroconversion rates were evident at different antigen dosages and within 7 days after the first booster. Quantitative stability/flexibility relationships analysis revealed that the RB and RC mutations affect rigidification of regions spanning residues 98-103, which constitutes a known immunodominant neutralizing B-cell epitope. A more detailed understanding of the immunogenic nature of RB and RC may provide insight into the fundamental relationship between local protein stability and antibody reactivity.
authors.affiliation: Department of Pharmaceutical Chemistry, Macromolecule and Vaccine Stabilization Center, University of Kansas, Lawrence, Kansas 66047.
authors.forename: Newton
authors.initials: N
authors.lastname: Wahome
authors.affiliation: Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York 12208.
authors.forename: Erin
authors.initials: E
authors.lastname: Sully
authors.affiliation: Department of Physics and Optical Science, University of North Carolina at Charlotte, Charlotte, North Carolina 28223.
authors.forename: Christopher
authors.initials: C
authors.lastname: Singer
authors.affiliation: Department of Pharmaceutical Chemistry, Macromolecule and Vaccine Stabilization Center, University of Kansas, Lawrence, Kansas 66047.
authors.forename: Justin C
authors.initials: JC
authors.lastname: Thomas
authors.affiliation: Department of Pharmaceutical Chemistry, Macromolecule and Vaccine Stabilization Center, University of Kansas, Lawrence, Kansas 66047.
authors.forename: Lei
authors.initials: L
authors.lastname: Hu
authors.affiliation: Department of Pharmaceutical Chemistry, Macromolecule and Vaccine Stabilization Center, University of Kansas, Lawrence, Kansas 66047.
authors.forename: Sangeeta B
authors.initials: SB
authors.lastname: Joshi
authors.affiliation: Department of Pharmaceutical Chemistry, Macromolecule and Vaccine Stabilization Center, University of Kansas, Lawrence, Kansas 66047.
authors.forename: David B
authors.initials: DB
authors.lastname: Volkin
authors.affiliation: Applied Bioinformatics Laboratory, Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66047.
authors.forename: Jianwen
authors.initials: J
authors.lastname: Fang
authors.affiliation: Department of Molecular Biosciences, Center for Computational Biology, University of Kansas, Lawrence, Kansas 66045.
authors.forename: John
authors.initials: J
authors.lastname: Karanicolas
authors.affiliation: Department of Physics and Optical Science, University of North Carolina at Charlotte, Charlotte, North Carolina 28223. Electronic address: djacobs1@uncc.edu.
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Jacobs
authors.affiliation: Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York 12208; Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, New York 12201. Electronic address: nicholas.mantis@health.ny.gov.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Mantis
authors.affiliation: Department of Pharmaceutical Chemistry, Macromolecule and Vaccine Stabilization Center, University of Kansas, Lawrence, Kansas 66047. Electronic address: middaugh@ku.edu.
authors.forename: C Russell
authors.initials: CR
authors.lastname: Middaugh
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood*; D000941:Antigens / Q000097:blood; D002619:Chemical Warfare Agents / Q000494:pharmacology; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012276:Ricin / Q000008:administration & dosage* / Q000235:genetics; D014612:Vaccines / Q000097:blood* / Q000737:chemistry; D022223:Vaccines, Subunit / Q000008:administration & dosage* / Q000235:genetics
chemical_list: D057134:Antibodies, Neutralizing; D000941:Antigens; D002619:Chemical Warfare Agents; C509236:RiVax; D014612:Vaccines; D022223:Vaccines, Subunit; D012276:Ricin
keywords: computational biology; immunology; physical stability; protein structure; ricin; vaccines