Phylogeny of North American Powassan virus.
To determine whether Powassan virus (POW) and deer tick virus (DTV) constitute distinct flaviviral populations transmitted by ixodid ticks in North America, we analysed diverse nucleotide sequences from 16 strains of these viruses. Two distinct genetic lineages are evident, which may be defined by geographical and host associations. The nucleotide and amino acid sequences of lineage one (comprising New York and Canadian POW isolates) are highly conserved across time and space, but those of lineage two (comprising isolates from deer ticks and a fox) are more variable. The divergence between lineages is much greater than the variation within either lineage, and lineage two appears to be more diverse genetically than is lineage one. Application of McDonald-Kreitman tests to the sequences of these strains indicates that adaptive evolution of the envelope protein separates lineage one from lineage two. The two POW lineages circulating in North America possess a pattern of genetic diversity suggesting that they comprise distinct subtypes that may perpetuate in separate enzootic cycles.
Ebel
Gregory D
GD
Laboratory of Public Health Entomology, Department of Immunology and Infectious Diseases, Harvard School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA1.
Spielman
Andrew
A
Laboratory of Public Health Entomology, Department of Immunology and Infectious Diseases, Harvard School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA1.
Telford
Sam R
SR
Laboratory of Public Health Entomology, Department of Immunology and Infectious Diseases, Harvard School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA1.
D020413:3' Untranslated Regions / Q000235:genetics; D000818:Animals; D004669:Encephalitis Viruses, Tick-Borne / Q000145:classification* / Q000235:genetics; D005589:Foxes / Q000821:virology*; D006801:Humans; D018884:Ixodes / Q000821:virology*; D008969:Molecular Sequence Data; D009656:North America; D010802:Phylogeny; D014759:Viral Envelope Proteins / Q000235:genetics; D017361:Viral Nonstructural Proteins / Q000235:genetics
D020413:3' Untranslated Regions; C096041:NS5 protein, flavivirus; D014759:Viral Envelope Proteins; D017361:Viral Nonstructural Proteins