Antibody Response in Mice Inoculated with DNA Expressing Foot-and-Mouth Disease Virus Capsid Proteins

Abstract

Candidate foot-and-mouth disease (FMD) DNA vaccines designed to produce viral capsids lacking infectious viral nucleic acid were evaluated. Plasmid DNAs containing a portion of the FMDV genome coding for the capsid precursor protein (P1-2A) and wild-type or mutant viral proteinase 3C (plasmids P12X3C or P12X3Cmut, respectively) were constructed. Cell-free translation reactions programmed with pP12X3C (wild-type 3C) and pP12X3C-mut produced a capsid precursor, but only the reactions programmed with the plasmid encoding the functional proteinase resulted in P1-2A processing and capsid formation. Baby hamster kidney (BHK) cells also produced viral capsid proteins when transfected with these plasmids. Plasmid P12X3C was administered to mice by intramuscular, intradermal, and epithelial (gene gun) inoculations. Anti-FMD virus (FMDV) antibodies were detected by radioimmunoprecipitation (RIP) and plaque reduction neutralization assays only in sera of mice inoculated by using a gene gun. When pP12X3C and pP12X3C-mut were inoculated into mice by using a gene gun, both plasmids elicited an antibody response detectable by RIP but only pP12X3C elicited a neutralizing antibody response. These results suggest that capsid formation in situ is required for effective immunization. Expression and stimulation of an immune response was enhanced by addition of an intron sequence upstream of the coding region, while addition of the FMDV internal ribosome entry site or leader proteinase (L) coding region either had no effect or reduced the immune response.

DNA vaccination against foot‐and‐mouth disease via electroporation: study of molecular approaches for enhancing VP1 antigenicity

“…cDNA coding for other capsid proteins has also been utilized for vaccination. Mason and colleagues have developed two types of DNA vaccine against the FMDV serotype A12 24–26. One contains a full‐length cDNA of the FMDV genome and the other a cDNA construct containing the P1‐2A and 3C (proteases) encoding regions which have been shown to elicit neutralizing antibody and partially protected test pigs against viral infection 24–26.…”

Comparative studies of the capsid precursor polypeptide P1 and the capsid protein VP1 cDNA vectors for DNA vaccination against foot‐and‐mouth disease virus

“…co-expression) of viral proteases, but not the VP1 protein by itself, can elicit a significant level of neutralizing antibodies and confer an effective level of protection against viral challenge with FMDV. Previous studies have shown that the whole virus particle or an 'authentic' empty capsid assembly was very important for induction of neutralizing antibodies and protection against viral challenge [21][22][23].…”

“…Previously, Mason and colleagues have developed two types of DNA vaccine against the FMDV serotype A12 [21][22][23]. One contains a full-length cDNA of the FMDV genome and the other a cDNA construct containing the P1-2A and 3C (proteases) encoding regions which have been shown to elicit neutralizing antibody and have partially protected test pigs against viral infection [21][22][23]. According to these cDNA constructs, it seems that capsid formation in situ is required for effective immunization [22][23][24][25].…”

“…One contains a full-length cDNA of the FMDV genome and the other a cDNA construct containing the P1-2A and 3C (proteases) encoding regions which have been shown to elicit neutralizing antibody and have partially protected test pigs against viral infection [21][22][23]. According to these cDNA constructs, it seems that capsid formation in situ is required for effective immunization [22][23][24][25]. The immunogens produced by capsid assembly may provide efficacious conformational epitopes [22,24].…”

“…According to these cDNA constructs, it seems that capsid formation in situ is required for effective immunization [22][23][24][25]. The immunogens produced by capsid assembly may provide efficacious conformational epitopes [22,24]. Huang et al [26] and Wong et al [27] designed another approach, where several plasmids encoding various FMDV epitopes and leading signal peptide sequence were employed in the study.…”