title: Genetic diversity and evolution of human metapneumovirus fusion protein over twenty years.
abstract: BACKGROUND
  Human metapneumovirus (HMPV) is an important cause of acute respiratory illness in children. We examined the diversity and molecular evolution of HMPV using 85 full-length F (fusion) gene sequences collected over a 20-year period.
  
  
  RESULTS
  The F gene sequences fell into two major groups, each with two subgroups, which exhibited a mean of 96% identity by predicted amino acid sequences. Amino acid identity within and between subgroups was higher than nucleotide identity, suggesting structural or functional constraints on F protein diversity. There was minimal progressive drift over time, and the genetic lineages were stable over the 20-year period. Several canonical amino acid differences discriminated between major subgroups, and polymorphic variations tended to cluster in discrete regions. The estimated rate of mutation was 7.12 x 10(-4) substitutions/site/year and the estimated time to most recent common HMPV ancestor was 97 years (95% likelihood range 66-194 years). Analysis suggested that HMPV diverged from avian metapneumovirus type C (AMPV-C) 269 years ago (95% likelihood range 106-382 years).
  
  
  CONCLUSIONS
  HMPV F protein remains conserved over decades. HMPV appears to have diverged from AMPV-C fairly recently.
authors.affiliation: Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN, USA. yangc@medimmune.com
authors.forename: Chin-Fen
authors.initials: CF
authors.lastname: Yang
authors.forename: Chiaoyin K
authors.initials: CK
authors.lastname: Wang
authors.forename: Sharon J
authors.initials: SJ
authors.lastname: Tollefson
authors.forename: Rohith
authors.initials: R
authors.lastname: Piyaratna
authors.forename: Linda D
authors.initials: LD
authors.lastname: Lintao
authors.forename: Marla
authors.initials: M
authors.lastname: Chu
authors.forename: Alexis
authors.initials: A
authors.lastname: Liem
authors.forename: Mary
authors.initials: M
authors.lastname: Mark
authors.forename: Richard R
authors.initials: RR
authors.lastname: Spaete
authors.forename: James E
authors.initials: JE
authors.lastname: Crowe
authors.forename: John V
authors.initials: JV
authors.lastname: Williams
mesh_terms: D019143:Evolution, Molecular; D014644:Genetic Variation; D006801:Humans; D029121:Metapneumovirus / Q000737:chemistry / Q000145:classification / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D014760:Viral Fusion Proteins / Q000737:chemistry / Q000235:genetics*
chemical_list: D014760:Viral Fusion Proteins