DEVELOPMENT OF A MARKER FOOT AND MOUTH DISEASE VIRUS VACCINE CANDIDATE THAT IS ATTENUATED IN THE NATURAL HOST

摘要

We have generated novel molecularly marked FMDV A24LL3DYR and A24LL3BPVKV3DYR vaccine candidates. The mutant viruses contain a deletion of the leader coding region (LL) rendering the virus attenuated in vivo and negative antigenic markers introduced in one or both of the viral non-structural 3Dpol and 3B proteins. Mutations were introduced into MAb F32-44 epitope in FMDV A24Cruzeiro spanning residues H27N31 in 3Dpol protein to obtain the homologous amino acid sequence of bovine rhinitis virus type B (BRV-2, Y27R31). Mutations in 3B consisted of a deletion of 3B1 and a mutation in 3B2 (RQKP->PVKV, found in BRV-2) that abolishes reactivity with MAb F8B. These attenuated marker viruses provide safe alternatives for FMD vaccine manufacturing. The vaccine platform includes unique restriction endonuclease sites for easy swapping of capsid proteins for different FMDV subtypes and serotypes. Chimeric viruses were produced to contain the capsid of distantly related type A/Turkey/06 or Asia type FMDV: Asia1-A24LL3BPVKV3DYR and A/Turkey/06 -A24LL3BPVKV3DYR. A24LL3DYR and A24LL3BPVKV3DYR mutant viruses produced no signs of FMD and no shedding of virulent virus in cattle. No clinical signs of disease or fever were observed and no transmission to in-contact animals was detected in pigs inoculated with live A24LL3DYR or the chimeric A-Turkey/06-A24LL3BPVKV3DYR or Asia1-A24LL3BPVKV3DYR viruses. Cattle immunized with chemically inactivated A24LL3DYR and A24LL3BPVKV3DYRvaccine candidates showed an efficacy comparable to a polyvalent commercial FMDV vaccine and protected 100% the animals from challenge with parental virus. The single and double marked-FMDV vaccine candidates used in conjunction with a cELISA provide a suitable target for DIVA companion tests.