title: Development of genetic markers in the non-structural protein 2 region of a US type 1 porcine reproductive and respiratory syndrome virus: implications for future recombinant marker vaccine development.
abstract: Porcine reproductive and respiratory syndrome virus (PRRSV) continues to be a major problem in the pork industry worldwide. The limitations of current PRRSV vaccines require the development of a new generation of vaccines. One of the key steps in future vaccine development is to include markers for diagnostic differentiation of vaccinated animals from those naturally infected with wild-type virus. Using a cDNA infectious clone of type 1 PRRSV, this study constructed a recombinant green fluorescent protein (GFP)-tagged PRRSV containing a deletion of an immunogenic epitope, ES4, in the nsp2 region. In a nursery pig disease model, the recombinant virus was attenuated with a lower level of viraemia in comparison with that of the parental virus. To complement the marker identification, GFP and ES4 epitope-based ELISAs were developed. Pigs immunized with the recombinant virus lacked antibodies directed against the corresponding deleted epitope, but generated a high-level antibody response to GFP by 14 days post-infection. These results demonstrated that this recombinant marker virus, in conjunction with the diagnostic tests, enables serological differentiation between marker virus-infected animals and those infected with the wild-type virus. This rationally designed marker virus will provide a basis for further development of PRRSV marker vaccines to assist with the control of PRRS.
authors.affiliation: Center for Infectious Disease Research and Vaccinology, Veterinary Science Department, South Dakota State University, Brookings, SD 57007, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Fang
authors.affiliation: Center for Infectious Disease Research and Vaccinology, Veterinary Science Department, South Dakota State University, Brookings, SD 57007, USA.
authors.forename: Jane
authors.initials: J
authors.lastname: Christopher-Hennings
authors.affiliation: Center for Infectious Disease Research and Vaccinology, Veterinary Science Department, South Dakota State University, Brookings, SD 57007, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Brown
authors.affiliation: Center for Infectious Disease Research and Vaccinology, Veterinary Science Department, South Dakota State University, Brookings, SD 57007, USA.
authors.forename: Haixia
authors.initials: H
authors.lastname: Liu
authors.affiliation: Center for Infectious Disease Research and Vaccinology, Veterinary Science Department, South Dakota State University, Brookings, SD 57007, USA.
authors.forename: Zhenhai
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Center for Infectious Disease Research and Vaccinology, Veterinary Science Department, South Dakota State University, Brookings, SD 57007, USA.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Lawson
authors.affiliation: Center for Infectious Disease Research and Vaccinology, Veterinary Science Department, South Dakota State University, Brookings, SD 57007, USA.
authors.forename: Rachael
authors.initials: R
authors.lastname: Breen
authors.affiliation: Center for Infectious Disease Research and Vaccinology, Veterinary Science Department, South Dakota State University, Brookings, SD 57007, USA.
authors.forename: Travis
authors.initials: T
authors.lastname: Clement
authors.affiliation: Center for Infectious Disease Research and Vaccinology, Veterinary Science Department, South Dakota State University, Brookings, SD 57007, USA.
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Gao
authors.affiliation: Center for Infectious Disease Research and Vaccinology, Veterinary Science Department, South Dakota State University, Brookings, SD 57007, USA.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Bao
authors.affiliation: Center for Infectious Disease Research and Vaccinology, Veterinary Science Department, South Dakota State University, Brookings, SD 57007, USA.
authors.forename: David
authors.initials: D
authors.lastname: Knudsen
authors.affiliation: Center for Infectious Disease Research and Vaccinology, Veterinary Science Department, South Dakota State University, Brookings, SD 57007, USA.
authors.forename: Russell
authors.initials: R
authors.lastname: Daly
authors.affiliation: Center for Infectious Disease Research and Vaccinology, Veterinary Science Department, South Dakota State University, Brookings, SD 57007, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Nelson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D006224:Cricetinae; D003546:Cysteine Endopeptidases / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D000939:Epitopes / Q000276:immunology; D017353:Gene Deletion; D005819:Genetic Markers; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D019318:Porcine Reproductive and Respiratory Syndrome / Q000276:immunology / Q000517:prevention & control* / Q000821:virology; D019316:Porcine respiratory and reproductive syndrome virus / Q000145:classification / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity; D013552:Swine; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D014765:Viral Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology
chemical_list: D000939:Epitopes; D005819:Genetic Markers; D010455:Peptides; D014614:Vaccines, Synthetic; D014765:Viral Vaccines; D049452:Green Fluorescent Proteins; D003546:Cysteine Endopeptidases; C078306:nsP2 proteinase