title: Toll-like receptor ligands enhance the protective effects of vaccination against porcine reproductive and respiratory syndrome virus in swine.
abstract: Porcine reproductive and respiratory syndrome virus (PRRSV) is mainly responsible for the heavy economic losses in pig industry in the world. Current vaccination strategies provide only a limited protection. Previous studies have demonstrated the immunostimulatory adjuvant effects of Toll-like receptor (TLR) ligands, synthetic double-stranded RNA polyriboinosinic polyribocytidylic [poly(I:C)], lipoteichoic acid (LTA) and CL097 in humans and animals. To study the effects of these compounds on the induction of PRRSV-specific immune responses, mice were immunized subcutaneously with killed virus (KV) antigens incorporating pairs of TLR ligands. It was found that poly(I:C) and CL097 induced the higher IFN-γ levels and PRRSV-specific antibodies, comparing with that KV with or without LTA in mice. Piglets were vaccinated with the KV mixed with poly(I:C) or CL097 and the protective effects of the vaccination were evaluated. The results showed that PRRSV-specific antibodies and T lymphocyte proliferation levels in KV mixed with poly(I:C) or CL097 groups were higher than those in KV group. Following challenge with PRRSV, pigs inoculated with KV mixed with poly(I:C) or CL097 showed lighter clinical signs, lower viremia and less pathological lesion of lungs, as compared to those of KV and challenge control groups. It indicated that co-administration of poly(I:C) and CL097 with killed PRRSV vaccine conferred higher protection against PRRSV challenge. TLR3 and TLR7/8 ligands are promising adjuvant candidates for the development of novel vaccines against PRRSV.
authors.affiliation: Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Zhang
authors.forename: Juan
authors.initials: J
authors.lastname: Bai
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Xiaoye
authors.initials: X
authors.lastname: Wang
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Li
authors.forename: Ping
authors.initials: P
authors.lastname: Jiang
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D007093:Imidazoles / Q000494:pharmacology*; D007371:Interferon-gamma / Q000097:blood; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D019318:Porcine Reproductive and Respiratory Syndrome / Q000473:pathology / Q000517:prevention & control*; D019316:Porcine respiratory and reproductive syndrome virus / Q000276:immunology*; D011804:Quinolines / Q000494:pharmacology*; D013552:Swine; D015164:Vaccines, Inactivated / Q000276:immunology*; D014765:Viral Vaccines / Q000276:immunology*
chemical_list: D000276:Adjuvants, Immunologic; D000914:Antibodies, Viral; C547051:CL097 compound; D007093:Imidazoles; D011804:Quinolines; D015164:Vaccines, Inactivated; D014765:Viral Vaccines; D007371:Interferon-gamma