title: SAT2 Foot-and-Mouth Disease Virus Structurally Modified for Increased Thermostability.
abstract: Foot-and-mouth disease virus (FMDV), particularly strains of the O and SAT serotypes, is notoriously unstable. Consequently, vaccines derived from heat-labile SAT viruses have been linked to the induction of immunity with a poor duration and hence require more frequent vaccinations to ensure protection.In silicocalculations predicted residue substitutions that would increase interactions at the interpentamer interface, supporting increased stability. We assessed the stability of the 18 recombinant mutant viruses in regard to their growth kinetics, antigenicity, plaque morphology, genetic stability, and temperature, ionic, and pH stability by using Thermofluor and inactivation assays in order to evaluate potential SAT2 vaccine candidates with improved stability. The most stable mutant for temperature and pH stability was the S2093Y single mutant, while other promising mutants were the E3198A, L2094V, and S2093H single mutants and the F2062Y-H2087M-H3143V triple mutant. Although the S2093Y mutant had the greatest stability, it exhibited smaller plaques, a reduced growth rate, a change in monoclonal antibody footprint, and poor genetic stability properties compared to those of the wild-type virus. However, these factors affecting production can be overcome. The addition of 1 M NaCl was found to further increase the stability of the SAT2 panel of viruses. The S2093Y and S2093H mutants were selected for future use in stabilizing SAT2 vaccines.IMPORTANCEFoot-and-mouth disease virus (FMDV) causes a highly contagious acute vesicular disease in cloven-hoofed livestock and wildlife. The control of the disease by vaccination is essential, especially at livestock-wildlife interfaces. The instability of some serotypes, such as SAT2, affects the quality of vaccines and therefore the duration of immunity. We have shown that we can improve the stability of SAT2 viruses by mutating residues at the capsid interface through predictive modeling. This is an important finding for the potential use of such mutants in improving the stability of SAT2 vaccines in countries where FMD is endemic, which rely heavily on the maintenance of the cold chain, with potential improvement to the duration of immune responses.
authors.affiliation: Transboundary Animal Disease Programme, ARC-Onderstepoort Veterinary Institute, Onderstepoort, South Africa.|Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Scott
authors.affiliation: Division of Structural Biology, University of Oxford, Headington, Oxford, United Kingdom.
authors.forename: Abhay
authors.initials: A
authors.lastname: Kotecha
authors.affiliation: The Pirbright Institute, Pirbright, Woking, United Kingdom.
authors.forename: Julian
authors.initials: J
authors.lastname: Seago
authors.affiliation: Division of Structural Biology, University of Oxford, Headington, Oxford, United Kingdom.
authors.forename: Jingshan
authors.initials: J
authors.lastname: Ren
authors.affiliation: Division of Structural Biology, University of Oxford, Headington, Oxford, United Kingdom.
authors.forename: Elizabeth E
authors.initials: EE
authors.lastname: Fry
authors.affiliation: Division of Structural Biology, University of Oxford, Headington, Oxford, United Kingdom.|Life Science Division, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, United Kingdom.
authors.forename: David I
authors.initials: DI
authors.lastname: Stuart
authors.affiliation: The Pirbright Institute, Pirbright, Woking, United Kingdom.
authors.forename: Bryan
authors.initials: B
authors.lastname: Charleston
authors.affiliation: Transboundary Animal Disease Programme, ARC-Onderstepoort Veterinary Institute, Onderstepoort, South Africa mareef@arc.agric.za.|Department of Microbiology and Plant Pathology, Faculty of Agricultural and Natural Sciences, University of Pretoria, Pretoria, South Africa.
authors.forename: Francois F
authors.initials: FF
authors.lastname: Maree
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D029544:Foot-and-Mouth Disease Virus / Q000235:genetics* / Q000276:immunology / Q000502:physiology*; D042822:Genomic Instability; D006863:Hydrogen-Ion Concentration; D000071497:Immunogenicity, Vaccine; D007477:Ions; D007700:Kinetics; D009154:Mutation; D065288:Serogroup; D012965:Sodium Chloride / Q000494:pharmacology; D013696:Temperature; D064166:Vaccine Potency; D014765:Viral Vaccines / Q000737:chemistry / Q000235:genetics*
chemical_list: D007477:Ions; D014765:Viral Vaccines; D012965:Sodium Chloride
keywords: FMDV; SAT2; stability