title: The evolution of porcine reproductive and respiratory syndrome virus: quasispecies and emergence of a virus subpopulation during infection of pigs with VR-2332.
abstract: GP5, the principal envelope glycoprotein of porcine reproductive and respiratory syndrome virus (PRRSV), contains a hypervariable region within the ectodomain which is responsible for generating diversity in field isolates. The purpose of this study was to gain insight into the possible origin of this diversity by following GP5 sequence changes in pigs exposed to PRRSV strain VR-2332 in utero. A region of the PRRS virus genome containing portions of ORF4 and ORF5 was amplified directly from tissues of infected pigs from birth to 132 days of age. We observed the emergence of a new PRRSV population, identified by a single nucleotide change in the ectodomain. The Asp to Asn change at amino acid 34 was also found as a minor component in pigs that expressed the wild-type sequence. The results from this study suggest that the variability in the ectodomain of ORF5 is the result of positive or negative selection, of which the mechanism remains to be determined.
authors.affiliation: Department of Biology-Microbiology, South Dakota State University, Brookings, South Dakota, 57007, USA. rowlandr@mg.sdstate.edu
authors.forename: R R
authors.initials: RR
authors.lastname: Rowland
authors.forename: M
authors.initials: M
authors.lastname: Steffen
authors.forename: T
authors.initials: T
authors.lastname: Ackerman
authors.forename: D A
authors.initials: DA
authors.lastname: Benfield
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D014644:Genetic Variation; D008198:Lymph Nodes / Q000821:virology; D008969:Molecular Sequence Data; D009154:Mutation; D009500:Neutralization Tests; D019318:Porcine Reproductive and Respiratory Syndrome / Q000821:virology*; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics* / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D013552:Swine; D014470:Umbilical Cord / Q000821:virology; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology
chemical_list: D000914:Antibodies, Viral; D014759:Viral Envelope Proteins; C114789:glycoprotein 5, PRRSV