# Spread and Evolution of West Nile virus in the United States

> **NIH NIH R56** · SCRIPPS RESEARCH INSTITUTE, THE · 2020 · $911,734

## Abstract

Since its emergence 20 years ago, West Nile virus (WNV) has become the most important mosquito-borne
virus in the United States. Cycles of WNV outbreaks have led to an estimated 7 million human infections
and have decimated certain bird populations. Even though there are expansive WNV surveillance and
vector control systems in place, we critically lack a detailed understanding of how the virus is spreading
and what drives outbreaks, which is integral to reducing the burden of disease. These knowledge gaps
include: ( 1 ) how WNV spreads regionally and nationally, ( 2 ) what facilitates emergence and spread, ( 3 ) if
WNV is evolving to local vector and host populations, and ( 4 ) how WNV genetic diversity influences virus
phenotypes. We hypothesize that there are ecological, biological, and genetic barriers that determine
endemic spread of WNV, leading to regional segregation of the virus. Furthermore, we predict that these
factors and their impact on WNV genetic diversity contribute to the patterns of WNV outbreaks.
Incorporating genomic approaches into traditional epidemiological and experimental investigations has
the power to give us deep insights into how viruses emerge, spread, and evolve. Therefore, to test our
hypotheses, and to uncover how virus movement and diversity contributes to outbreaks, we have
established the “WestNile 4K Project” and will complete the following research: ( 1 ) generate and analyze
an ultra large dataset of at least 8,000 new WNV genomes, by sequencing thousands of viruses from our
large network of collaborating public health partners across the United States, and ( 2 ) directly examine
the impact of WNV genetics on virus fitness and phenotype using a series of controlled laboratory
experiments. The rationale is that by completion of our research goals, we will obtain a high definition
reconstruction of WNV emergence, spread, and evolution, allowing us to define WNV transmission
networks, investigate the role of virus diversity in outbreaks, and examine the impact of WNV genetics on
virus phenotype. By sharing our data and analyses in real-time with our public health partners and the
research community, our goal is to provide up-to-date resources to help inform WNV control.

## Key facts

- **NIH application ID:** 10239500
- **Project number:** 1R56AI149004-01A1
- **Recipient organization:** SCRIPPS RESEARCH INSTITUTE, THE
- **Principal Investigator:** Kristian Graugaard Andersen
- **Activity code:** R56 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $911,734
- **Award type:** 1
- **Project period:** 2020-09-02 → 2022-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10239500

## Citation

> US National Institutes of Health, RePORTER application 10239500, Spread and Evolution of West Nile virus in the United States (1R56AI149004-01A1). Retrieved via AI Analytics 2026-08-17 from https://api.ai-analytics.org/grant/nih/10239500. Licensed CC0.

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