Genetic variability and evolutionary analysis of parietaria mottle virus: role of selection and genetic exchange.

The genetic variability and evolution of parietaria mottle virus (PMoV) of the genus Ilarvirus was studied by analyzing nucleotide sequences of 2b and CP genes from isolates collected in different countries. Phylogenetic analysis showed that PMoV isolates clustered in different clades: one (clade I) composed of only Italian isolates and three clades (clades II-IV) including the Spanish isolates. The Greek isolate GrT-1 used in this study was in clade IV for the CP phylogenetic tree whereas it formed a separate branch in the 2b phylogenetic tree. The nucleotide sequence diversity of both the 2b and CP genes was low (0.062 ± 0.006 and 0.063 ± 0.006 for 2b and CP, respectively) but higher than those of other ilarviruses. Distribution of synonymous and nonsynonymous substitutions revealed that 2b and CP proteins are under purifying selection, with some positions under diversifying selection. Genetic exchange among Spanish isolates was also detected.