title: Field avian metapneumovirus evolution avoiding vaccine induced immunity.
abstract: Live avian metapneumovirus (AMPV) vaccines have largely brought turkey rhinotracheitis (TRT) under control in Europe but unexplained outbreaks still occur. Italian AMPV longitudinal farm studies showed that subtype B AMPVs were frequently detected in turkeys some considerable period after subtype B vaccination. Sequencing showed these to be unrelated to the previously applied vaccine. Sequencing of the entire genome of a typical later isolate showed numerous SH and G protein gene differences when compared to both a 1987 Italian field isolate and the vaccine in common use. Experimental challenge of vaccinated birds with recent virus showed that protection was inferior to that seen after challenge with the earlier 1987 isolate. Field virus had changed in key antigenic regions allowing replication and leading to disease in well vaccinated birds.
authors.affiliation: Dipartimento di Sanità Pubblica Veterinaria e Patologia Animale, University of Bologna, Ozzano Emilia (BO), Italy. elena.catelli@unibo.it
authors.forename: Elena
authors.initials: E
authors.lastname: Catelli
authors.forename: Caterina
authors.initials: C
authors.lastname: Lupini
authors.forename: Mattia
authors.initials: M
authors.lastname: Cecchinato
authors.forename: Enrico
authors.initials: E
authors.lastname: Ricchizzi
authors.forename: Paul
authors.initials: P
authors.lastname: Brown
authors.forename: Clive J
authors.initials: CJ
authors.lastname: Naylor
mesh_terms: D000220:Adaptation, Biological; D000818:Animals; D019143:Evolution, Molecular; D016679:Genome, Viral; D007558:Italy; D029121:Metapneumovirus / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification; D018184:Paramyxoviridae Infections / Q000517:prevention & control / Q000662:veterinary* / Q000821:virology; D010802:Phylogeny; D011201:Poultry Diseases / Q000276:immunology / Q000517:prevention & control* / Q000821:virology*; D012367:RNA, Viral / Q000235:genetics; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D014422:Turkeys; D014765:Viral Vaccines / Q000276:immunology*
chemical_list: D012367:RNA, Viral; D014765:Viral Vaccines