Engineering Viable Foot-and-Mouth Disease Viruses with Increased Thermostability as a Step in the Development of Improved Vaccines

Abstract

We have rationally engineered foot-and-mouth disease virus to increase its stability against thermal dissociation into subunits without disrupting the many biological functions needed for its infectivity. Amino acid side chains located near the capsid intersubunit interfaces and either predicted or found to be dispensable for infectivity were replaced by others that could establish new disulfide bonds or electrostatic interactions between subunits. Two engineered viruses were normally infectious, genetically stable, and antigenically indistinguishable from the natural virus but showed substantially increased stability against irreversible dissociation. Electrostatic interactions mediated this stabilizing effect. For foot-and-mouth disease virus and other viruses, some evidence had suggested that an increase in virion stability could be linked to an impairment of infectivity. The results of the present study show, in fact, that virion thermostability against dissociation into subunits may not be selectively constrained by functional requirements for infectivity. The thermostable viruses obtained, and others similarly engineered, could be used for the production, using current procedures, of foot-and-mouth disease vaccines that are less dependent on a faultless cold chain. In addition, introduction of those stabilizing mutations in empty (nucleic acid-free) capsids could facilitate the production of infectionrisk-free vaccines against the disease, one of the economically most important animal diseases worldwide.

The pH Stability of Foot-and-Mouth Disease Virus Particles Is Modulated by Residues Located at the Pentameric Interface and in the N Terminus of VP1

“…Understanding the molecular basis that control capsid stability is relevant not only for the knowledge of a basic aspect of FMDV biology, but also to gain information to improve stability of conventional vaccines based on inactivated virions (12,36) or future vaccines based on empty capsids (37). In this study, we have isolated a panel of FMDV mutants with increased sensitivity to acidic pH by performing infections in the presence of NH 4 Cl.…”

Intra-serotype SAT2 chimeric foot-and-mouth disease vaccine protects cattle against FMDV challenge

“…Chimeric, genome-length clones could form the basis for the rational engineering of viruses with improved structural features as vaccine seed viruses. Viruses can be engi-neered with structurally stabilising mutations to be less reliant on a faultless cold chain [25,26,51], with BHK-21 cell culture adap-tation and increased antigen yield [31] or defective FMDV can be generated with deletions in various parts of the genome [52][53][54]. Furthermore, viruses can be engineered with modifications incorporated into the genome to support serological differentiation of infected from vaccinated animals [33] for surveillance of FMD in sub-Saharan Africa.…”

Identification of Positively Charged Residues in Enterovirus 71 Capsid Protein VP1 Essential for Production of Infectious Particles

“…Taking the findings together, conditional thermostable mutants can be generated by altering the charge characteristics of VP1. Rational engineering of viable EV71 virus with increased thermostability by introduction of a stabilizing mutation(s) using reverse genetic tools is an attractive approach for development of improved vaccines which reduce the dependence on a cold chain (36,37). Sensitivities of mutants and revertants to an EV71 entry inhibitor.…”