Sequencing

11th Annual Sequencing, Finishing, and Analysis in the Future Meeting
THE NORTHWARD DISSEMINATION OF A NOVEL
CLADE OF WEST NILE VIRUS IS ASSOCIATED WITH
2012 DISEASE OUTBREAK IN NORTH TEXAS
Wednesday, 1st June 14:40 La Fonda Ballroom Talk (OS‐3.03)
Chukwuemika Aroh 1 , Mary D’Anton 2 , Beth Levine 1 , Nan Yan 1 , Edward Wakeland 1
1 UT Southwestern Medical Center, 2 Texas Department of State Health Services
West Nile Virus (WNV) is the leading cause of mosquito‐borne encephalitis in the United States
and thus is of significant public health concern. Since its arrival in the northeast region of United
States in 1999, WNV has disseminated to the rest of the country and has led to frequent epidemics
in birds, horses, and humans. For a long time it has been known that mid‐central United States,
from Texas to North Dakota, has the highest incidence of human West Nile disease, but the cause
remains unclear. In this study we sequenced novel WNV isolates from environmental samples in
Texas from 2012 to 2015 and analyzed these along with endemic WNV isolates in TX and other
parts of the United States. Our results suggest that two lineages of WNV arrived in TX from
northeastern United States between 2008 and 2012. These two lineages were associated with the
most recent WNV epidemic in 2012 and 2013. Of these lineages, only the lineage characterized by a
mutation in the NS2a region of the WNV genome spread into northern states in 2012, suggesting
that this lineage may have readily infected migratory birds. Additionally, in 2013 this northward
dissemination was again observed as 2012 strains from Houston‐gulf area replaced mutant NS2a
bearing strains in North TX area. These observations suggest a general northward dissemination of
WNV strains in mid‐central United States that may lead to the rapid dissemination of pathogenic
viruses during an epidemic.
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