title: Transmission bottlenecks and RNAi collectively influence tick-borne flavivirus evolution.
abstract: Arthropod-borne RNA viruses exist within hosts as heterogeneous populations of viral variants and, as a result, possess great genetic plasticity. Understanding the micro-evolutionary forces shaping these viruses can provide insights into how they emerge, adapt, and persist in new and changing ecological niches. While considerable attention has been directed toward studying the population dynamics of mosquito-borne viruses, little is known about tick-borne virus populations. Therefore, using a mouse andIxodes scapularistick transmission model, we examined Powassan virus (POWV;Flaviviridae, Flavivirus) populations in and between both the vertebrate host and arthropod vector. We found that genetic bottlenecks, RNAi-mediated diversification, and selective constraints collectively influence POWV evolution. Together, our data provide a mechanistic explanation for the slow, long-term evolutionary trends of POWV, and suggest that all arthropod-borne viruses encounter similar selective pressures at the molecular level (i.e. RNAi), yet evolve much differently due to their unique rates and modes of transmission.
authors.affiliation: Department of Microbiology Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, CO, USA.
authors.forename: Nathan D
authors.initials: ND
authors.lastname: Grubaugh
authors.affiliation: Department of Microbiology Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, CO, USA.
authors.forename: Claudia
authors.initials: C
authors.lastname: Rückert
authors.affiliation: The Connecticut Agricultural Experiment Station, Center for Vector Biology and Zoonotic Diseases, New Haven, CT, USA.
authors.forename: Philip M
authors.initials: PM
authors.lastname: Armstrong
authors.affiliation: The Connecticut Agricultural Experiment Station, Center for Vector Biology and Zoonotic Diseases, New Haven, CT, USA.
authors.forename: Angela
authors.initials: A
authors.lastname: Bransfield
authors.affiliation: The Connecticut Agricultural Experiment Station, Center for Vector Biology and Zoonotic Diseases, New Haven, CT, USA.
authors.forename: John F
authors.initials: JF
authors.lastname: Anderson
authors.affiliation: Department of Microbiology Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, CO, USA.
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Ebel
authors.affiliation: The Connecticut Agricultural Experiment Station, Center for Vector Biology and Zoonotic Diseases, New Haven, CT, USA.
authors.forename: Doug E
authors.initials: DE
authors.lastname: Brackney
keywords: Ixodes; Powassan virus; RNAi; evolution; flavivirus; tick.