West Nile virus, Usutu virus, Zika virus, and St. Louis encephalitis virus are all transmitted by mosquitoes and cause a significant threat to human health.

Nisha Duggal, an assistant professor of biomedical sciences and pathobiology in the      Virginia-Maryland College of Veterinary Medicine, has recently received three R21 grants from the National Institutes of Health (NIH) totaling $825,000 to combat the transmission of these diseases, develop therapeutics, and predict future disease in humans.

“Mosquito-borne viruses are emerging globally, with increasing host range and disease potential. With this funding, we are determining who is most at risk for transmission and looking to develop future vaccines and therapeutics,” said Duggal, who is also an affiliated faculty member of the Center for Emerging, Zoonotic, and Arthropod-borne Pathogens and the Fralin Life Sciences Institute.

Duggal’s long-term goal is to understand how viral adaptation during emergence affects virus transmission and pathogenesis. Her interests involve emerging viruses, host-virus co-evolution, virus transmission, and immunity in birds.

With these grants, Duggal and her research team will tackle Usutu virus, West Nile virus, and St. Louis encephalitis virus transmission and pathogenesis in mosquitos and birds; study Zika virus sexual transmission in humans; and use molecular virology and phylogenetic tools to predict future viral emergence and disease.

“Nisha’s innovative research on these medically important, mosquito-borne viruses fits nicely in an important thematic area of vector biology and vector-borne diseases within the Center for Emerging, Zoonotic and Arthropod-borne Pathogens. These grants will allow Nisha to continue her ongoing collaborations both within and outside of Virginia Tech and further establish her as a rising star in the field of emerging and vector-borne viral diseases,” said X.J. Meng, University Distinguished Professor and interim executive director of the Fralin Life Sciences Institute.

West Nile virus and Usutu virus research

West Nile virus and Usutu virus are closely related mosquito-borne viruses that cause disease in the human nervous system. West Nile virus emerged from Africa and Europe into the U.S. in 1999, and it is now the most common mosquito-borne disease in the continental U.S.; however, no vaccines or therapeutics are available. Usutu virus is emerging in Europe, where it has been introduced at least three times from Africa by migratory birds, and human disease cases are increasing.

For this project, Duggal is developing a reverse genetics system by transforming the viral RNA into DNA that can be more easily manipulated for experiments. Duggal hopes to discover cross-reactivity in immune responses to determine if future vaccines can be used for both viruses. The long-term goal is the development of therapeutics to reduce disease.

Zika virus research

Outbreaks of Zika virus disease have been recorded in Africa, the Americas, Asia, and the Pacific. Zika virus is also transmitted from mother to fetus during pregnancy and through sexual contact, transfusion of blood and blood products, and organ transplantation.

Duggal and her team plan to use this grant funding to identify the infectious potential of Zika virus in semen and the window of time in which infection is possible between sexual partners. Upon successful completion of the proposed research, the anticipated impact of this work will be the identification of the cellular source of Zika virus in semen and the ability to assess and prevent the risk of Zika virus sexual transmission.

West Nile virus, St. Louis encephalitis virus, and Usutu virus research

West Nile virus, St. Louis encephalitis virus, and Usutu virus are closely related mosquito-borne viruses that are maintained in overlapping bird and mosquito transmission cycles, with spillover to humans.

Duggal and her team will study North American birds and mosquitoes to identify possible transmission cycles. The long-term goal of this project is to understand the factors that influence novel virus emergence in order to predict future outbreaks in humans.

“These projects require a lot of collaboration, and we are thrilled to partner with Dr. James Weger-Lucarelli at Virginia Tech and Dr. Angela Bosco-Lauth at Colorado State University to move this research forward. It is important to track viruses of concern in order to prevent future pandemics,” said Duggal.

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