Exploring Genetic Diversity and Focal Hot-Spots of Deer Tick Virus in Wells National Estuarine Research Reserve Público

Abstract

Powassan virus (POWV) is a tick-borne flavivirus that can cause severe encephalitis and meningitis in humans. It is the sole tick-borne encephalitis serological complex virus found in North America. It has two lineages, with the second lineage, known as deer tick virus (DTV), being more prevalent and associated with a tick vector that also transmits Lyme disease and other tick-borne diseases. This study used phylogenetic analyses to understand the geographic distribution and evolution of DTV lineages and sub-lineages over time. We collected and aligned complete genome sequences of DTV from the National Center for Biotechnology Information (NCBI) GenBank database, filtered them based on quality and relevance, and created a maximum likelihood tree to determine phylogenetic relationships. We included 99 sequences in the final analysis, including samples from ticks collected at hotspot locations in Wells National Estuarine Research Reserve (WNERR) in Maine, USA. The phylogenetic analysis conducted in this study reveals four major clades from WNERR, each showing different levels of genetic diversity. Transects within WNERR also exhibited different levels of viral diversity, with some transects associated with only one clade and others linked to two or more clades. This indicated the potential differences in the composition and distribution of viral variants across different transects. This study uniquely examines the viral diversity of Powassan virus on a fine-scale geographic level, shedding light on the dynamics of DTV populations in a localized area. Our results provide insights into the geographic distribution and evolution of DTV lineages and highlight the importance of understanding the ecology and epidemiology of tick-borne diseases for effective surveillance and control strategies. Further research is needed to investigate the factors driving the persistence and spread of DTV in tick populations and its potential impact on human health.

Table of Contents

Introduction ................................................................................................................................. 1

Aims........................................................................................................................................ 1

Preliminary Data...................................................................................................................... 2

Figure 1. Map of WNERR transects and hotspots ......................................................................... 3

Methods ...................................................................................................................................... 3

Collecting and aligning complete genomes................................................................................... 3

Table 1. Reference sequence metadata ........................................................................................ 5

Assessing temporal signal and building a maximum likelihood tree in Interactive Tree of Life (iTOL). 6

Results ........................................................................................................................................ 6

Figure 2. Maximum likelihood tree with cities and states annotated................................................ 7

Figure 3. Maximum likelihood tree with major clades annotated ...................................................10

Figure 4. Maximum likelihood tree showing the relationship between major clades and transects.....13

Discussion ..................................................................................................................................14

References ..................................................................................................................................17 

About this Master's Thesis

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School	Rollins School of Public Health
Department	Epidemiology
Degree	M.P.H.
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Public Health
Palabra Clave	emerging virus powassan virus phylodynamics tick-borne flavivirus deer tick virus
Committee Chair / Thesis Advisor	Gonzalo Vazquez-Prokopec, Emory University
Committee Members	Anne Piantadosi, Emory University

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