A Prime-Boost Vaccination Strategy in Cattle to Prevent Foot-and-Mouth Disease Using a "Single-Cycle" Alphavirus Vector and Empty Capsid Particles

PLoS One. 2016 Jun 13;11(6):e0157435. doi: 10.1371/journal.pone.0157435. eCollection 2016.

Abstract

Foot-and-mouth disease (FMD) remains one of the most economically important infectious diseases of production animals globally. Vaccination can successfully control this disease, however, current vaccines are imperfect. They are made using chemically inactivated FMD virus (FMDV) that is produced in large-scale mammalian cell culture under high containment conditions. Here, we have expressed the FMDV capsid protein precursor (P1-2A) of strain O1 Manisa alone or with the FMDV 3C protease (3Cpro) using a "single cycle" packaged alphavirus self-replicating RNA based on Semliki Forest virus (SFV). When the FMDV P1-2A was expressed with 3Cpro then processing of the FMDV capsid precursor protein is observed within cells and the proteins assemble into empty capsid particles. The products interact with anti-FMDV antibodies in an ELISA and bind to the integrin αvβ6 (a cellular receptor for FMDV). In cattle vaccinated with these rSFV-FMDV vectors alone, anti-FMDV antibodies were elicited but the immune response was insufficient to give protection against FMDV challenge. However, the prior vaccination with these vectors resulted in a much stronger immune response against FMDV post-challenge and the viremia observed was decreased in level and duration. In subsequent experiments, cattle were sequentially vaccinated with a rSFV-FMDV followed by recombinant FMDV empty capsid particles, or vice versa, prior to challenge. Animals given a primary vaccination with the rSFV-FMDV vector and then boosted with FMDV empty capsids showed a strong anti-FMDV antibody response prior to challenge, they were protected against disease and no FMDV RNA was detected in their sera post-challenge. Initial inoculation with empty capsids followed by the rSFV-FMDV was much less effective at combating the FMDV challenge and a large post-challenge boost to the level of anti-FMDV antibodies was observed. This prime-boost system, using reagents that can be generated outside of high-containment facilities, offers significant advantages to achieve control of FMD by vaccination.

MeSH terms

  • Animals
  • Antibodies, Viral / immunology*
  • Capsid / immunology*
  • Capsid Proteins / genetics
  • Capsid Proteins / immunology
  • Capsid Proteins / therapeutic use
  • Cattle / immunology
  • Cattle / virology*
  • Cell Line
  • Cricetinae
  • Foot-and-Mouth Disease / immunology
  • Foot-and-Mouth Disease / prevention & control*
  • Foot-and-Mouth Disease Virus / genetics
  • Foot-and-Mouth Disease Virus / immunology*
  • Genetic Vectors / genetics
  • Plasmids / genetics
  • Semliki forest virus / genetics
  • Swine
  • Transfection
  • Vaccination
  • Viral Vaccines / genetics
  • Viral Vaccines / immunology*
  • Viral Vaccines / therapeutic use

Substances

  • Antibodies, Viral
  • Capsid Proteins
  • Viral Vaccines

Grants and funding

This work was supported by the Danish Council for Independent Research | Technology and Production Sciences (FTP grant 09-070549) to CP and GJB, plus Defra (UK) project number SE1127 to TJ and internal funding from DTU National Veterinary Institute to GJB.