title: Attempts to enhance cross-protection against porcine reproductive and respiratory syndrome viruses using chimeric viruses containing structural genes from two antigenically distinct strains.
abstract: Due to significant antigenic variations between field isolates of porcine reproductive and respiratory syndrome virus (PRRSV), suboptimal cross-protection between different viruses impedes the effective control of PRRS via vaccination. Our previous study showed that chimeric viruses containing mixed structural genes from two distinct strains (VR2332 and JA142) of PRRSV were highly susceptible to the viral neutralizing activity of antisera generated against both parental strains. In this study, three chimeric viruses (JAP5, JAP56 and JAP2-6) were constructed by replacing ORF5, ORFs 5 and 6, and ORFs 2-6 of VR2332 with the corresponding genes of JA142, respectively, and their ability to confer cross-protection against challenge with the VR2332 and JA142 strains was evaluated in vivo. A total of 114 pigs were divided into 6 groups, and each group was intramuscularly injected with one of the 3 chimeric viruses (n=16 pigs per group), VR2332 (n=24), JA142 (n=24), or sham inoculum (n=18). At 44days post-inoculation (dpi), these pigs were further divided into 15 groups (n=6 or 8 pigs per group) and intranasally challenged with VR2332, JA142, or sham inoculum. All pigs inoculated with one of the chimeric viruses prior to challenge had lower viremia levels than the challenge control pigs. Prior inoculation with JAP56 markedly decreased viremia to nearly undetectable levels in pigs challenged with either VR2332 or JA142. These results suggest that chimeric viruses harboring mixed structural genes from two distinct PRRSV strains can provide protection against both donor viruses.
authors.affiliation: Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50010, USA.
authors.forename: Dong
authors.initials: D
authors.lastname: Sun
authors.affiliation: College of Veterinary Medicine, Chonbuk National University, Iksan, Republic of Korea.
authors.forename: Amina
authors.initials: A
authors.lastname: Khatun
authors.affiliation: College of Veterinary Medicine, Chonbuk National University, Iksan, Republic of Korea. Electronic address: kwi0621@jbnu.ac.kr.
authors.forename: Won-Il
authors.initials: WI
authors.lastname: Kim
authors.affiliation: Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50010, USA.
authors.forename: Vickie
authors.initials: V
authors.lastname: Cooper
authors.affiliation: Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50010, USA.
authors.forename: Yong-Il
authors.initials: YI
authors.lastname: Cho
authors.affiliation: Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50010, USA.
authors.forename: Chong
authors.initials: C
authors.lastname: Wang
authors.affiliation: Viral Disease Division, Animal Plant Fisheries Quarantine Agency, Anyang, Republic of Korea.
authors.forename: Eun-Jin
authors.initials: EJ
authors.lastname: Choi
authors.affiliation: Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50010, USA; Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50010, USA. Electronic address: kyoon@iastate.edu.
authors.forename: Kyoung-Jin
authors.initials: KJ
authors.lastname: Yoon
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D000940:Antigenic Variation; D056738:Cross Protection; D016366:Open Reading Frames; D010802:Phylogeny; D019318:Porcine Reproductive and Respiratory Syndrome / Q000276:immunology* / Q000517:prevention & control; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics* / Q000276:immunology*; D059386:Reverse Genetics; D013552:Swine; D014611:Vaccination; D015678:Viral Structural Proteins / Q000235:genetics*; D014765:Viral Vaccines / Q000235:genetics / Q000276:immunology*; D014766:Viremia
chemical_list: D000914:Antibodies, Viral; D015678:Viral Structural Proteins; D014765:Viral Vaccines
keywords: Chimeric virus; Cross protection; Infectious clone; PRRSV; Reverse genetics; Structural genes; Vaccine