Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Construction and assessment of the efficacy of ODN, CpG rich constructs, ubiquitin fusion constructs and Sindbis based constructs coding for gB and gD

Studies were performed to improving the efficacy of nucleic acid vaccines i) by using auto-replicative vectors (Sindbis based replicons) for enhanced foreign gene, ii) by using CpG motifs for adjuvation and iii) by redirecting antigen processing through ubiquitination to improve the cell-mediated immune response.

Ad i) DNA vaccines constituting of pSIN (Sindbis) constructs encoding PRV glycoproteins gB, gC or gD of Pseudorabies virus (PRV) were constructed. The efficacy of these constructs were tested and compared with the conventional DNA vaccine constructs. A cocktail of DNA vaccines constituting of three pSIN encoding PRV glycoproteins gB, gC or gD was shown to induce a similar specific and protective immunity against PRV infection as compared to the conventional pcDNA3 vector-base vaccine. Furthermore, the dose could be lowered from 340µg to 13µg without loosing out on efficacy.

Ad ii) The adjuvant activity of a porcine-specific type A CpG-containing oligodeoxynucleotide (CpG-ODN) was evaluated. CpG-ODN improved the PrV-specific humoral immune response and cell-mediated immune (CMI) response, and improved clinical protection against lethal PrV-infection.

Ad iii) Plasmids encoding individually PRV gB, gC and gD fused to ubiquitin (Ubi-PRV-pcDNA3) were constructed and compared to or native glycoproteins constructs (PRV-pcDNA3). Whereas there were no differences in the PRV-specific IgG1 type antibody responses, vaccination with the ubiqituinated constructs resulted in a delay in the IgG2 response. In terms of the CMI response, ubiquitinated constructs resulted in a CMI response, which seemingly weaned off earlier than when using non-ubiquitinated constructs.

Ubiquitinated constructs did not result in improved protection against challenge infection.

Reported by

AFSSA
Po box 53
F-22440 Ploufragan
France