Toll-like receptor agonists as adjuvants for inactivated porcine reproductive and respiratory syndrome virus (PRRSV) vaccine

Sandra Vreman*, Joanne McCaffrey, Ditta J. Popma-de Graaf, Hans Nauwynck, Huub F.J. Savelkoul, Anne Moore, Johanna M.J. Rebel, Norbert Stockhofe-Zurwieden

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

3 Citations (Scopus)

Abstract

Toll-like receptor (TLR) agonists can effectively stimulate antigen-presenting cells (APCs) and are anticipated to be promising adjuvants in combination with inactivated vaccines. In this study, the adjuvant potential of three different TLR-agonists were compared with an oil-in-water (O/W) adjuvant in combination with inactivated porcine reproductive and respiratory syndrome virus (iPRRSV) applied by different administration routes: intramuscular (i.m.) or into the skin using dissolving microneedle (DMN) patches. Pigs received a prime vaccination followed by a booster vaccination four weeks later. TLR1/2 (Pam3Cys), TLR7/8 (R848) or TLR9 (CpG ODN) agonists were used as adjuvant in combination with iPRRSV strain 07V063. O/W adjuvant (Montanide™) was used as reference control adjuvant and one group received a placebo vaccination containing diluent only. All animals received a homologous challenge with PRRSV three weeks after the booster vaccination. Antibody and IFN-γ production, serum cytokines and viremia were measured at several time-points after vaccination and/or challenge, and lung pathology at necropsy. Our results indicate that a TLR 1/2, 7/8 or 9 agonist as adjuvant with iPRRSV does not induce a detectable PRRSV-specific immune response, independent of the administration route. However, the i.m. TLR9 agonist group showed reduction of viremia upon challenge compared to the non-vaccinated animals, supported by a non-antigen-specific IFN-γ level after booster vaccination and an anamnestic antibody response after challenge. Montanide™-adjuvanted iPRRSV induced antigen-specific immunity after booster combined with reduction of vireamia. Skin application of TLR7/8 agonist, but not the other agonists, induced a local skin reaction. Further research is needed to explore the potential of TLR agonists as adjuvants for inactivated porcine vaccines with a preference for TLR9 agonists.

Original languageEnglish
Pages (from-to)27-37
Number of pages11
JournalVeterinary Immunology and Immunopathology
Volume212
DOIs
Publication statusPublished - 1 Jun 2019

Keywords

  • Adjuvant
  • PRRSV
  • Skin vaccination
  • Toll-like receptor agonist
  • Vaccine

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