Nucleotide sequence comparison of the 3'-terminal regions of severe, mild, and non-papaya infecting strains of papaya ringspot virus.

The 3'-terminal 2,561 nucleotide residues of the severe HA strain of papaya ringspot virus (PRSV) was determined. Comparison with the published sequence of the mild strain PRSV HA 5-1 showed that they shared a 99.4% identity in their 3'-terminal 2,235 residues. There were ten residues different at the NIb gene, resulting in five amino acid changes, and two residues different in the coat protein gene, resulting in two amino acid changes. The 3'-untranslated regions were identical, but HA contained two more nucleotides (AG) at the 3' extreme. Comparison with the published non-papaya infecting type W strain PRSV-W revealed that they shared a 97.9% identity in their 3'-terminal 2,235 residues. There were 40 nucleotides different in the coding region, which resulted in four amino acid changes in the NIb gene and six in the CP gene, and seven nucleotides different in the 3'-untranslated region.