title: Glycoprotein gene truncation in avian metapneumovirus subtype C isolates from the United States.
abstract: The length of the published glycoprotein (G) gene sequences of avian metapneumovirus subtype-C (aMPV-C) isolated from domestic turkeys and wild birds in the United States (1996-2003) remains controversial. To explore the G gene size variation in aMPV-C by the year of isolation and cell culture passage levels, we examined 21 turkey isolates of aMPV-C at different cell culture passages. The early domestic turkey isolates of aMPV-C (aMPV/CO/1996, aMPV/MN/1a-b, and 2a-b/97) had a G gene of 1,798 nucleotides (nt) that coded for a predicted protein of 585 amino acids (aa) and showed >97% nt similarity with that of aMPV-C isolated from Canada geese. This large G gene got truncated upon serial passages in Vero cell cultures by deletion of 1,015 nt near the end of the open reading frame. The recent domestic turkey isolates of aMPV-C lacked the large G gene but instead had a small G gene of 783 nt, irrespective of cell culture passage levels. In some cultures, both large and small genes were detected, indicating the existence of a mixed population of the virus. Apparently, serial passage of aMPV-C in cell cultures and natural passage in turkeys in the field led to truncation of the G gene, which may be a mechanism of virus evolution for survival in a new host or environment.
authors.affiliation: Department of Veterinary and Biomedical Sciences, University of Minnesota, 301C Vet Sci Bldg, 1971 Commonwealth Avenue, Saint Paul, MN 55108, USA.
authors.forename: Binu T
authors.initials: BT
authors.lastname: Velayudhan
authors.forename: Qingzhong
authors.initials: Q
authors.lastname: Yu
authors.forename: Carlos N
authors.initials: CN
authors.lastname: Estevez
authors.forename: Kakambi V
authors.initials: KV
authors.lastname: Nagaraja
authors.forename: David A
authors.initials: DA
authors.lastname: Halvorson
mesh_terms: D000818:Animals; D001483:Base Sequence; D002522:Chlorocebus aethiops; D029121:Metapneumovirus / Q000235:genetics* / Q000302:isolation & purification*; D008969:Molecular Sequence Data; D018184:Paramyxoviridae Infections / Q000662:veterinary* / Q000821:virology; D011201:Poultry Diseases / Q000821:virology*; D017384:Sequence Deletion; D012692:Serial Passage; D014421:Turkey; D014481:United States; D014709:Vero Cells; D014759:Viral Envelope Proteins / Q000235:genetics*
chemical_list: D014759:Viral Envelope Proteins