What is new on molecular characteristics of Avian metapneumovirus
strains circulating in Europe?
Abstract
In the present study one hundred and sixteen partial G gene sequences of
Avian metapneumovirus (aMPV) subtype B, obtained during routine
diagnostics in different European Countries in the last few years
(2014-2019), were analysed by sequence and phylogenetic analyses in
order to draw an updated picture of the molecular characteristics of
circulating strains. Nucleotide sequences were compared with other
sequences of European and extra-European aMPV-Bs collected prior to that
period or retrieved from GenBank. Phylogenetic relationships among the
aMPV-B strains, reconstructed using the Maximum Likelihood method
implemented in MEGA X, demonstrated that aMPV-B has evolved in Europe
from its first appearance, frequently displaying a clear relation with
the geographic area of detection. The 40% of aMPV-B viruses analysed
were classified as vaccine-derived strains, being phylogenetically
related, and showing high nucleotide identity with live commercial
vaccine strains licensed in Europe. The remaining 60% were classified
as field strains since they clustered separately and showed a low
nucleotide identity with vaccines and vaccine-derived strains. The
phylogenetic tree showed that the virus has continued to evolve from its
first appearance in the ’80s since more recently detected strains
belonged to clades phylogenetically distant from the older strains.
Unlike vaccine-derived strains, field strains tended to cluster
according to their geographic origin and irrespective of the host
species where the viruses had been detected. In conclusion, the
molecular characterization of aMPV-B and the differentiation between
vaccines and field strains through G gene sequence analysis can be a
useful tool towards correct diagnosis and should be routinely applied in
order to better address the control strategies.