The Cholera Toxin B Subunit (CTB) Fused to the Porcine Arterivirus Matrix M and GP5 Envelope Proteins Fails to Enhance the GP5-Specific Antibody Response in Pigs Immunized with Adenovectors

Citation

Roques, E., Lessard, M., Archambault, D. (2015). The Cholera Toxin B Subunit (CTB) Fused to the Porcine Arterivirus Matrix M and GP5 Envelope Proteins Fails to Enhance the GP5-Specific Antibody Response in Pigs Immunized with Adenovectors. Molecular Biotechnology, [online] 57(8), 701-708. http://dx.doi.org/10.1007/s12033-015-9861-6

Abstract

The porcine reproductive and respiratory syndrome virus (PRRSV) is an arterivirus of the Arteriviridae family. As the current commercial vaccines are incompletely protective effective against PRRSV infection, we developed a vaccine strategy using replicating but non-disseminating adenovectors (rAdVs) expressing the PRRSV M matrix protein in fusion with the neutralizing major epitope-carrying GP5 envelope protein (Roques et al. in Vet Res 44:17, 2013). Although production of GP5-specific antibodies (Abs) was observed, no PRRSV-specific neutralizing Abs (NAbs) were induced in pigs given the rAdVs expressing M-GP5 or M-GP5m (GP5m being a mutant form of GP5). Nevertheless, partial protection was observed in the M-GP5m-rAdV-inoculated pigs experimentally infected with PRRSV. Here, we determined the impact of the cholera toxin B subunit (CTB, known for its adjuvant effect) in fusion with the C-terminus of M-GP5m on the Ab response to PRRSV. Three-week-old pigs were immunized twice both intramuscularly and intranasally at 3-week intervals with rAdV-expressing the green fluorescent protein (rAdV-GFP), rAdV-M-GP5m, or rAdV-M-GP5m-CTB. Pigs immunized with rAdV-M-GP5m showed a high level of serum GP5-specific Abs (as determined by an indirect ELISA). In contrast, CTB in fusion with M-GP5m had an unexpected severe negative impact on GP5-specific Ab production. PRRSV-specific NAbs could not be detected in any pigs of all groups.

Publication date

2015-08-25