title: Efficacy of Type 2 PRRSV vaccine against Chinese and Vietnamese HP-PRRSV challenge in pigs.
abstract: Porcine reproductive and respiratory syndrome virus (PRRSV) causes significant reproductive losses in the sow herd and respiratory disease in growing pigs. The virus belongs to the family Arteriviridae and there are two major genotypes. Type 1 is represented by Lelystad virus, the European prototype virus, and Type 2 is represented by the North American prototype virus, VR-2332. Depending on husbandry, immune status of the herd, and virulence of the isolate, the severity of disease and magnitude of economic loss can be variable. Vaccine use is not always successful indicating a lack of cross-protection between vaccine strains and circulating wild-type viruses. To date, there is no clear method to demonstrate if a vaccine confers protection against a specific isolate except for empirical animal studies. In 2006, a new lineage of Type 2 PRRSV emerged in Chinese swine herds that were suffering dramatic losses resulting in those viruses being described as "Highly Pathogenic PRRSV" (HP-PRRSV). Experimental reproduction of severe disease with HP-PRRSV isolates and virus derived from HP-PRRSV clones demonstrated the causal role of this virus. Recently, partial heterologous protection has been reported for Type 1 and Type 2 attenuated PRRSV vaccines against challenge by different Chinese HP-PRRSV isolates providing some hope for reducing economic loss. This paper reports the efficacy of a commercially available Type 2 attenuated vaccine in young pigs against heterologous challenge with a Chinese and Vietnamese HP-PRRSV isolate. When compared to unvaccinated pigs, vaccination decreased the length of viremia and viral titer, diminished the time of high fever and reduced macroscopic lung scores following homologous and heterologous PRRSV challenge. These results demonstrate the potential use of vaccine as an aid in the control of HP-PRRSV outbreaks.
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, Agricultural Research Service, USDA, Ames, IA, USA. Electronic address: kelly.lager@ars.usda.gov.
authors.forename: Kelly M
authors.initials: KM
authors.lastname: Lager
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, Agricultural Research Service, USDA, Ames, IA, USA.
authors.forename: Sarah N
authors.initials: SN
authors.lastname: Schlink
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, Agricultural Research Service, USDA, Ames, IA, USA.
authors.forename: Susan L
authors.initials: SL
authors.lastname: Brockmeier
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, Agricultural Research Service, USDA, Ames, IA, USA.
authors.forename: Laura C
authors.initials: LC
authors.lastname: Miller
authors.affiliation: Diagnostic Medicine Pathobiology, Kansas State University, Manhattan, KS, USA.
authors.forename: Jamie N
authors.initials: JN
authors.lastname: Henningson
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, Agricultural Research Service, USDA, Ames, IA, USA.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Kappes
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, Agricultural Research Service, USDA, Ames, IA, USA.
authors.forename: Marcus E
authors.initials: ME
authors.lastname: Kehrli
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, Agricultural Research Service, USDA, Ames, IA, USA.
authors.forename: Crystal L
authors.initials: CL
authors.lastname: Loving
authors.affiliation: Veterinary Diagnostic & Production Animal Medicine, Iowa State University, Ames, IA, USA.
authors.forename: Baoquing
authors.initials: B
authors.lastname: Guo
authors.affiliation: National Veterinary Service Laboratories, Animal Plant Health Inspection Service, USDA, Ames, IA, USA.
authors.forename: Sabrina L
authors.initials: SL
authors.lastname: Swenson
authors.affiliation: China Agricultural University, Beijing, China.
authors.forename: Han-Chun
authors.initials: HC
authors.lastname: Yang
authors.affiliation: Virus and Prion Research Unit, National Animal Disease Center, Agricultural Research Service, USDA, Ames, IA, USA.
authors.forename: Kay S
authors.initials: KS
authors.lastname: Faaberg
mesh_terms: D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000821:virology; D056724:Immunity, Humoral; D008168:Lung / Q000473:pathology / Q000821:virology; D019318:Porcine Reproductive and Respiratory Syndrome / Q000517:prevention & control*; D019316:Porcine respiratory and reproductive syndrome virus / Q000145:classification*; D013552:Swine; D014611:Vaccination / Q000662:veterinary; D014613:Vaccines, Attenuated / Q000276:immunology; D019562:Viral Load; D014765:Viral Vaccines / Q000276:immunology*
chemical_list: D014613:Vaccines, Attenuated; D014765:Viral Vaccines
keywords: HP-PRRSV; PRRSV vaccine; Swine