Homogeneity of Powassan virus populations in naturally infected Ixodes scapularis.
Powassan virus (POWV, Flaviviridae: Flavivirus) is the sole North American member of the tick-borne encephalitis complex and consists of two distinct lineages that are maintained in ecologically discrete enzootic transmission cycles. The underlying genetic mechanisms that lead to niche partitioning in arboviruses are poorly understood. Therefore, intra- and interhost genetic diversity was analyzed to determine if POWV exists as a quasispecies in nature and quantify selective pressures within and between hosts. In contrast to previous reports for West Nile virus (WNV), significant intrahost genetic diversity was not observed. However, pN (0.238) and d(N)/d(S) ratios (0.092) for interhost diversity were similar to those of WNV. Combined, these data suggest that purifying selection and/or population bottlenecks constrain quasispecies diversity within ticks. These same selective and stochastic mechanisms appear to drive minor sequence changes between ticks. Moreover, Powassan virus populations seem not to be structured as quasispecies in naturally infected adult deer ticks.
Brackney
Doug E
DE
University of New Mexico School of Medicine, Department of Pathology, Albuquerque, New Mexico, USA.
Brown
Ivy K
IK
Nofchissey
Robert A
RA
Fitzpatrick
Kelly A
KA
Ebel
Gregory D
GD
D000818:Animals; D016000:Cluster Analysis; D004669:Encephalitis Viruses, Tick-Borne / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D019143:Evolution, Molecular; D014644:Genetic Variation; D018884:Ixodes / Q000821:virology*; D009656:North America; D010802:Phylogeny; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA