title: Baculovirus expression of proteins of porcine reproductive and respiratory syndrome virus strain Olot/91. Involvement of ORF3 and ORF5 proteins in protection.
abstract: Porcine reproductive and respiratory syndrome virus (PRRSV) is a new arterivirus that has spread rapidly all around the world in the last few years. The genomic region containing open reading frames (ORFs) 2 to 7 of PRRSV Spanish isolate Olot/91 was cloned and sequenced. The genomic sequence shared 95% identity with Lelystad and Tübingen isolates and between 61-64% with the ORF7 region of the American isolates. ORFs 2 to 7 were inserted into recombinant baculoviruses downstream of the polyhedrin promoter. Only ORFs 2, 3 5 and 7 were expressed in insect cells as detected by PRRS-specific pig antisera. To analyze the immunogenicity of these proteins and their ability to confer protection, Sf9 cells infected with recombinant baculoviruses expressing ORFs 3, 5 and 7 gene products were used to immunize pregnant sows, either individually or in combination. The results obtained indicate that ORFs 3 and 5 gene products could be major candidates for the development of a vaccine against PRRS since they conferred 68.4 and 50% protection, respectively, as evaluated by the number of piglets born alive and healthy at the time of weaning. In addition, piglets born to sows immunized with ORFs 3 and 5 proteins were seronegative to PRRSV after weaning, indicating absence of viral replication. ORF7 is the most immunogenic protein of PRRSV, but the antibodies induced in sows are non-protective and may even interfere with protection.
authors.affiliation: Laboratorios Sobrino, Gerona, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Plana Duran
authors.forename: I
authors.initials: I
authors.lastname: Climent
authors.forename: J
authors.initials: J
authors.lastname: Sarraseca
authors.forename: A
authors.initials: A
authors.lastname: Urniza
authors.forename: E
authors.initials: E
authors.lastname: Cortés
authors.forename: C
authors.initials: C
authors.lastname: Vela
authors.forename: J I
authors.initials: JI
authors.lastname: Casal
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis; D016367:Baculoviridae / Q000235:genetics; D001483:Base Sequence; D002460:Cell Line; D018076:DNA, Complementary / Q000235:genetics; D004279:DNA, Viral / Q000235:genetics; D005260:Female; D015870:Gene Expression; D005822:Genetic Vectors; D007114:Immunization; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D019318:Porcine Reproductive and Respiratory Syndrome / Q000276:immunology / Q000517:prevention & control / Q000821:virology; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics* / Q000276:immunology*; D011247:Pregnancy; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D012098:Reproduction; D018411:Spodoptera; D013552:Swine; D014614:Vaccines, Synthetic / Q000235:genetics / Q000276:immunology / Q000494:pharmacology; D014764:Viral Proteins / Q000235:genetics / Q000276:immunology; D014765:Viral Vaccines / Q000235:genetics / Q000276:immunology / Q000494:pharmacology
chemical_list: D000914:Antibodies, Viral; D018076:DNA, Complementary; D004279:DNA, Viral; D011994:Recombinant Proteins; D014614:Vaccines, Synthetic; D014764:Viral Proteins; D014765:Viral Vaccines