title: Cysteine residues of the porcine reproductive and respiratory syndrome virus small envelope protein are non-essential for virus infectivity.
abstract: Porcine reproductive and respiratory syndrome virus (PRRSV) open reading frame (ORF) 2a contains a small internal ORF (2b) capable of encoding a protein of 73 aa, termed E protein. The function of E protein is currently unknown. The E protein possesses two cysteines at positions 49 and 54 that are highly conserved among North American isolates. In the present study, it was shown that E protein did not homodimerize with itself nor did it heterodimerize with the nucleocapsid (N) protein. However, E protein was interactive non-covalently with itself or with the N protein as shown by pull-down assays. The significance of the E protein cysteine residues on virus replication was determined using an infectious clone. Each cysteine was substituted by serine and the mutations were introduced into a full-length clone of PRRSV. When transfected into Marc-145 cells, all cysteine mutant clones induced PRRSV-specific cytopathic effects and produced infectious progeny virus. The data indicate that cysteine residues in the E protein are not essential for replication of North American genotype PRRSV.
authors.affiliation: Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
authors.forename: Changhee
authors.initials: C
authors.lastname: Lee
authors.affiliation: Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
authors.forename: Dongwan
authors.initials: D
authors.lastname: Yoo
mesh_terms: D000818:Animals; D002460:Cell Line; D003545:Cysteine / Q000235:genetics / Q000378:metabolism*; D019318:Porcine Reproductive and Respiratory Syndrome / Q000821:virology; D019316:Porcine respiratory and reproductive syndrome virus / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D013552:Swine; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000502:physiology*
chemical_list: D014759:Viral Envelope Proteins; D003545:Cysteine