The Prevalence of Bourbon Virus in Field-Collected Ticks in Saint Louis County, Missouri

Undergraduate #81
Discipline: Ecology Environmental and Earth Sciences
Subcategory: Microbiology/Immunology/Virology
Session: 1
Room: Hoover

Derek McFarland - Harris-Stowe State University
Co-Author(s): Adrianus Boon, Ph.D., Washington University School of Medicine, St. Louis, MO; Solny Adalsteinsson, Ph.D, Washington University Tyson Research Center, Eureka, MO

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Bourbon virus (BRBV) is an emerging RNA virus that can be transmitted to both humans and wildlife through the bite of infected Amblyomma americanum ticks. Since the recent discovery of BRBV in 2014, cases of human disease have been reported, some of which have been fatal. However, there is still not much known about the epidemiology, clinical treatments, or ecology of BRBV. Host-seeking ticks were collected during May and June by drag-sampling in old field, glade, and forest habitats at Tyson Research Center in Eureka, Missouri. Ideally, ~20,000 ticks are needed to assess the incidence of BRBV. Ticks were stored in vials and kept at -80? C or on dry ice before and after identification. Using a dichotomous key and dissecting microscope, ticks were sorted into pools defined by life stage, sex, species, collection date, and location. Pools with adult ticks are limited to 5 individuals while nymphal pools are limited to 25 individuals. Pools will be homogenized and tested for the prevalence of BRBV using RNA extraction and quantitative rRT-PCR with virus-specific primers and probes. So far, 1,472 ticks have been successfully identified only 10-20% of the targeted population. Most of the identified ticks were Lone Star ticks (A. americanum) and accounted for 98.91% of the sample (1,456 ticks: 282 adult males; 263 adult females; 911 nymphs). The American dog tick (Dermacentor variabilis) made up 0.68% (10 ticks: 4 adult males; 5 adult females; 1 nymph) and the blacklegged tick (Ixodes scapularis) represented 0.41% of the sample. Previously, studies in eastern Kansas found BRBV in adult male A. americanum with an infection rate (IR) of 0.32 per 1,000 adult males (~1 in 3,125 adult males) and an IR of 0.07 per 1,000 nymphs. Therefore, we hypothesize that BRBV will be found in approximately 1 out of 3,000 adults ? with adults having higher prevalence than nymphs. More ticks are needed to fully assess the incidence of BRBV in Tyson Research Center.

Funder Acknowledgement(s): NIH-NIDDK STEP-UP Grant

Faculty Advisor: Solny Adalsteinsson, PhD, solny.adalsteinsson@wustl.edu

Role: I was performed all facets of this research. Tick collectiion, homogenizations, identifications, QRTPCR, RNA Extractions, Quantification, and Modeling.