title: Inactivated and subunit vaccines against porcine reproductive and respiratory syndrome: Current status and future direction.
abstract: Within a few years of its emergence in the late 1980s, the PRRS virus had spread globally to become the foremost infectious disease concern for the pork industry. Since 1994, modified live-attenuated vaccines against porcine reproductive and respiratory syndrome virus (PRRSV-MLV) have been widely used, but have failed to provide complete protection against emerging and heterologous field strains of the virus. Moreover, like many other MLVs, PRRSV-MLVs have safety concerns including vertical and horizontal transmission of the vaccine virus and several documented incidences of reversion to virulence. Thus, the development of efficacious inactivated vaccines is warranted for the control and eradication of PRRS. Since the early 1990s, researchers have been attempting to develop inactivated PRRSV vaccines, but most of the candidates have failed to elicit protective immunity even against homologous virus challenge. Recent research findings relating to both inactivated and subunit candidate PRRSV vaccines have shown promise, but they need to be pursued further to improve their heterologous efficacy and cost-effectiveness before considering commercialization. In this comprehensive review, we provide information on attempts to develop PRRSV inactivated and subunit vaccines. These includes various virus inactivation strategies, adjuvants, nanoparticle-based vaccine delivery systems, DNA vaccines, and recombinant subunit vaccines produced using baculovirus, plant, and replication-deficient viruses as vector vaccines. Finally, future directions for the development of innovative non-infectious PRRSV vaccines are suggested. Undoubtedly there remains a need for novel PRRSV vaccine strategies targeted to deliver cross-protective, non-infectious vaccines for the control and eradication of PRRS.
authors.affiliation: Food Animal Health Research Program, Ohio Agricultural Research and Development Center, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH, United States. Electronic address: gourapura.1@osu.edu.
authors.forename: Gourapura J
authors.initials: GJ
authors.lastname: Renukaradhya
authors.affiliation: Department of Biomedical Sciences and Pathobiology, College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States.
authors.forename: Xiang-Jin
authors.initials: XJ
authors.lastname: Meng
authors.affiliation: Zoetis, Kalamazoo, MI, United States.
authors.forename: Jay G
authors.initials: JG
authors.lastname: Calvert
authors.affiliation: Boehringer Ingelheim Vetmedica, Inc., Ames, IA, United States.
authors.forename: Michael
authors.initials: M
authors.lastname: Roof
authors.affiliation: Virology Swine Research Unit, National Animal Disease Center, U.S. Department of Agriculture, Ames, IA, United States. Electronic address: kelly.lager@ars.usda.gov.
authors.forename: Kelly M
authors.initials: KM
authors.lastname: Lager
mesh_terms: D000818:Animals; D055808:Drug Discovery / Q000639:trends; D019318:Porcine Reproductive and Respiratory Syndrome / Q000517:prevention & control*; D019316:Porcine respiratory and reproductive syndrome virus / Q000276:immunology*; D013552:Swine; D015164:Vaccines, Inactivated / Q000276:immunology / Q000302:isolation & purification; D022223:Vaccines, Subunit / Q000276:immunology / Q000302:isolation & purification; D014765:Viral Vaccines / Q000276:immunology* / Q000302:isolation & purification*
chemical_list: D015164:Vaccines, Inactivated; D022223:Vaccines, Subunit; D014765:Viral Vaccines
keywords: Cross-protection; Delivery system; Immunity; Inactivated/killed PRRSV; Porcine reproductive and respiratory syndrome virus (PRRSV)