title: Efficacy of Type 2 porcine reproductive and respiratory syndrome virus (PRRSV) vaccine against the 2010 isolate of Vietnamese highly pathogenic PRRSV challenge in pigs.
abstract: The efficacy of a commercial attenuated live type 2 porcine reproductive and respiratory syndrome (PRRS) vaccine was tested under experimental infection with a highly virulent Vietnamese virus isolated from a diseased pig affected with highly pathogenic PRRS (HP-PRRS) using specific pathogen-free (SPF) pigs. Twenty-five 4-week-old SPF pigs were divided into three groups as follows: pigs vaccinated with a single dose of the vaccine (Group 1, n=10), unvaccinated pigs (Group 2, n=10) and unvaccinated and non-infectious control pigs (Group 3, n=5). Four weeks later, Groups 1 and 2 were challenged with a 1 ml inoculum containing 1 × 105.550% tissue culture infectious dose (TCID50)/ml of a Vietnamese HP-PRRS virus isolated in 2010 via the intranasal route. Animals were monitored during the subsequent two-week period post-challenge and necropsied for virological and pathological assays. Results showed a significant reduction in viral replication and shedding in vaccinated pigs compared to unvaccinated pigs. The non-vaccinated pigs showed severe pyrogenic and respiratory illness with marked systematic lesions including interstitial pneumonia and thymic atrophy. In contrast, vaccinated pigs recovered quickly from fever with only mild pathological manifestations. Therefore, although viral shedding was still noted, immunization with the live PRRS vaccine did indeed reduce viral replication and disease severity, suggesting its utility in minimizing outbreaks of HP-PRRS.
authors.affiliation: Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, 3-1-5 Kannondai, Tsukuba, Ibaraki 305-0856 Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Iseki
authors.forename: Kenji
authors.initials: K
authors.lastname: Kawashima
authors.forename: Nguyen
authors.initials: N
authors.lastname: Tung
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Inui
authors.forename: Mitsutaka
authors.initials: M
authors.lastname: Ikezawa
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Shibahara
authors.forename: Makoto
authors.initials: M
authors.lastname: Yamakawa
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D001831:Body Temperature; D019318:Porcine Reproductive and Respiratory Syndrome / Q000276:immunology / Q000473:pathology / Q000517:prevention & control*; D019316:Porcine respiratory and reproductive syndrome virus; D012367:RNA, Viral / Q000032:analysis; D013552:Swine; D014613:Vaccines, Attenuated / Q000008:administration & dosage; D019562:Viral Load; D014765:Viral Vaccines / Q000008:administration & dosage*; D017201:Virus Shedding
chemical_list: D000914:Antibodies, Viral; D012367:RNA, Viral; D014613:Vaccines, Attenuated; D014765:Viral Vaccines