EVOLUTION OF THE FUSION (F), ATTACHMENT (G), AND NUCLEOPROTEIN (N) GENES FROM THE AVIAN METAPNEUMOVIRUS SUBGROUP A

Abstract

Avian metapneumovirus (aMPV), the primary causative agent of severe rhinotracheitis in turkeys, is associated with the swollen head syndrome in chickens and it is a source of significant economic losses during animal production. In this study, the partial sequences of the genes predicted to encode the fusion protein (F), attachment protein (G), and nucleoprotein (N) of six Brazilian aMPV isolates were analyzed and compared with previously published data for the aMPV genes. A phylogenetic analysis of the nucleotide sequences indicated that these Brazilian isolates have the same genetic subtype, previously named subtype A (aMPV/A). An analysis of the synonymous and non-synonymous nucleotide substitution ratio (dn/ds) for the F, G, and N genes yielded values higher than 1 when comparing the sequences of the aMPV/A viruses with those of viruses in other aMPV subgroups. However, the average dn/ds ratio was lower than 1 for the F, G and N genes when comparing sequences within the aMPV/A subgroup. From these results, the selective pressure analysis revealed a negative selection based on the F, G, and N genes among the aMPV/A viruses. Moreover, because different aMPV subgroups are highly diverse, the low dn/ds ratio for F, G and N genes among the aMPV/A viruses indicates that these genes are subject to positive selection. DOI:  http://dx.doi.org/10.17525/vrrjournal.v16i1-2.52