Phylogenetic tree of HRSV-A strains.

<p>The phylogenetic tree was constructed based on a 624-nucleotide fragment of the G protein, consisting of the two hypervariable regions. The nucleotide sequences of the Belgian strains isolated during 5 consecutive epidemic seasons (2006–2011) were compared with reference strains from Italy (ITA), Madrid (MAD), Montevideo (MON), West Virginia (WV) and Birmingham (BIR). The outgroup is represented by the Long strain. Bootstrap values are indicated at the internal nodes and are calculated for 1000 replicates by using the neighbour joining method. Only bootstrap values >70 are shown. The numbers between brackets are the number of strains identical to one shown in the tree. The amino acid lengths predicted for the G protein are indicated next to the Belgian isolates. For both the GA2 and GA5 genotypes, a strong temporal clustering of the strains per epidemic season is observed.