Field avian metapneumovirus evolution avoiding vaccine induced immunity.
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.
Catelli
Elena
E
Dipartimento di Sanità Pubblica Veterinaria e Patologia Animale, University of Bologna, Ozzano Emilia (BO), Italy. elena.catelli@unibo.it
Lupini
Caterina
C
Cecchinato
Mattia
M
Ricchizzi
Enrico
E
Brown
Paul
P
Naylor
Clive J
CJ
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*
D012367:RNA, Viral; D014765:Viral Vaccines