Protecting Human and Animal Health by Mitigating the Spread of Viruses
ARS research informs and provides solutions to improve the U.S. biodefense posture, a cross-cutting issue for both agriculture and public health. The risk of disease introduction—whether natural, intentional, or accidental—is increasing due to climate change and the increased movement of animals, plants, arthropods, and people around the globe. These diseases are a threat to food security and to human, animal, and environmental health. The following FY 2020 accomplishments highlight multidisciplinary efforts across ARS to prevent, mitigate, and respond to the spread of viruses.
COVID antiviral cotton facemasks. During the COVID-19 enforced maximal telework period ARS researchers at New Orleans, LA, in collaboration with a medical trauma wound dressing company, revealed that a jointly developed cotton nonwoven product exhibited antiviral activity. The natural compound in cotton (hydrogen peroxide) was discovered by ARS and tested by a contract company and was found to have antiviral activity based on a molecular model of SARS-CoV-2 virus. The product exhibited 99.999 percent antiviral activity after 1 hour of contact with the fabric. Nonwoven cotton will be studied with collaborators to determine its ability to inhibit COVID-19, which is caused by the current SARS-CoV-2 virus. Following testing by a secondary company to obtain a Food and Drug Administration-approved ISO test for antiviral textiles, the company plans to develop a prototype for use in facemasks.
Integrated West Nile virus (WNV) early warning surveillance system developed. West Nile fever/encephalitis is the most important mosquito-borne disease in the continental United States. The disease is caused by a flavivirus that is separated into distinct lineages, with lineage 1 (L1) and lineage 2 (L2) encompassing all WNV known isolates associated with human and veterinary disease. Currently, all known U.S. WNV isolates belong to L1. L2 isolates, usually found in sub-Saharan Africa, were recently found in Europe and caused large human and equine WNV outbreaks. The invasive threat and risk of WNV L2 invading the United States is significant because recent evidence has demonstrated that North American mosquito species are competent vectors of WNV L2 isolates from Africa and Europe. ARS scientists in Greece associated with the European Biological Control Laboratory designed an integrated WNV early warning surveillance system specifically targeting the L2 strains. The system relies on detecting viral RNA in field-collected mosquitoes and screening sentinel chickens for WNV-specific antibodies. The surveillance system was successfully implemented and provided information on WNV mosquito circulation and enzootic transmission 1 month prior to human cases, thereby allowing for targeted and proactive vector control interventions. Knowledge of the WNV L2 ecology in Europe combined with optimized field-based surveillance systems and laboratory diagnostic tools can be applied to enhance early detection and early warning systems to control and reduce this emerging threat.
Under-the-radar dengue virus infections in natural populations of Aedes aegypti mosquitoes. Metagenomics has helped identify dengue virus in Florida prior to any human infection. ARS researchers in Stoneville, MS, have demonstrated the ability to monitor vector-borne diseases ahead of outbreaks using metagenomics. To date, the current U.S. public health system’s response to outbreaks has been largely reactive, but this research shows that by monitoring mosquito populations, it may be possible to identify emerging mosquito-borne diseases in high-risk, high-tourism areas of the United States to enable proactive, targeted vector control before potential outbreaks occur.
Venereal transmission of Vesicular Stomatitis Virus in biting midges. Biting midges are well-known agricultural pests that transmit vesicular stomatitis virus (VSV) to cattle, horses, and swine. Vesicular stomatitis outbreaks occur every 3–8 years in the United States and result in significant economic losses due to animal disease, animal movement restrictions, and quarantines. In temperate regions, viruses appear to overwinter in the absence of infected animals through unknown mechanisms, resulting in new infections the following year. ARS scientists in Manhattan, KS, collaborated with Kansas State University to examine whether VSV could pass between male and female midges during mating to better understand whether virus may be maintained in insect populations in multi-year outbreaks. They found that during mating, VSV-infected females could transmit virus to uninfected naïve males that had never been exposed to the virus, and that infected males could transmit virus to uninfected naïve females. This research shows the importance of males in VSV transmission dynamics, and the role vectors may play in the maintenance of VSV. This is the first evidence for venereal transmission of any arbovirus (viruses that infect arthropods) in biting midges, and the first evidence for venereal transmission of VSV in any known vector species. These results highlight the need to incorporate alternative routes of transmission in understanding arbovirus outbreaks, and could lead to a more comprehensive understanding of: 1) potential virus persistence in nature between outbreaks; 2) the ability of some virus strains to survive through the winter leading to multi-year outbreaks; and 3) virus transmission dynamics during VSV outbreaks.