Table 1. Nucleotide divergence for open reading frame sequences between representative West Nile virus strains and other closely related strains from North America, Arizona, USA, 2010*.

Strain	Nucleotide divergence (%) from
	NY99	Cluster A	Cluster B	Cluster C
AZ10–581	0.58	0.25–0.52	0.66–0.85	0.61–1.10
AZ10–91	0.66	0.74–1.04	0.49–0.52	0.69–1.16
AZ10–892	0.65	0.84–1.18	0.92–1.04	0.27–0.62

*Strains used for analysis in each cluster are those color coded with representative AZ10 strains and shown in Figure 2, panel B. For cluster A: BSL2–2005 (SD 2005; GenBank accession no. DQ666452), BSL2–09 (NV 2009, JF957175), BSL4–11 (AZ 2011, JQ700438); cluster B: v4530 (NM 2005, HM756677), 144WG-AZ06PI (AZ 2006, GQ507482); cluster C: v4798 (NY 2004, HM756671), BSL3–10 (AZ 2010, JF957186), BSL2–10 (AZ 2010 JF957185), BSL23–11 (AZ 2011, JQ700440).