Figure 7
Prevalence of N(A 90 ) in genotype 1 PRRSV. PRRSV strains carrying an amino acid other than a threonine at position 90 of N are represented by colored dots in a phylogenetic tree based on 225 ORF7 sequences, with blue for alanine, red for valine and green for serine. The fraction (and percentage) of strains harboring an alanine at position 90 are indicated for each subtype.