VESICULAR STOMATITIS VIRUS IN THE ENVIRONMENT: SURVIVABILITY IN NORTH PLAINS GRASSLAND SPECIES

Authors: Drolet, Barbara; Stuart, Melissa

Submitted to: American Society for Virology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 1/11/2005
Publication Date: 6/22/2005
Citation: Drolet, B.S., Stuart, M.A. 2005. Vesicular stomatitis virus in the environment: survivability in north plains grassland species. American Society for Virology Meeting. Paper No. 42-1.

Interpretive Summary: Vesicular stomatitis virus (VSV) is an insect transmitted pathogen which causes economically important, sporadic outbreaks in horses and cattle in the western U.S. When cattle are infected, the excessive salivation that results is laden with virus and contaminates the pastures. Research emphasis on VSV epidemiology has primarily focused on blood feeding insects. Recently, however, grasshoppers have been shown to amplify VSV if they ingest cattle saliva containing virus. If, in turn, uninfected cattle ingest these virus infected grasshoppers, they can become infected. We investigated whether virus which might be shed by infected animals could survive in grassland pastures. Several species common to North Plains grasslands were found to harbor the virus for up to 24 hours, providing a significant window of opportunity for grasshoppers to ingest and replicate virus. This study contributes to the evidence that grasshoppers may play a role in the spread of VSV in the western U.S.

Technical Abstract: Vesicular stomatitis virus (VSV) causes economically important, sporadic outbreaks in horses and cattle in the western U.S. Once in the herd, virus is transmitted between animals by direct contact of virus-laden saliva. However, insects are believed to play important roles in the initial introduction of the virus into the herd from some unknown natural reservoir, as well as between animal herds of the same or different species. Although research emphasis has traditionally been on hematophagous insects as transmission vectors, the migratory grasshopper Melanoplus sanguinipes has recently been shown to be an efficient amplifying reservoir and possible mechanical vector for VSV. Based on these findings, we investigated whether typical range plant species found in the western U.S. cattle pastures, and potentially eaten by these grasshoppers, were capable of sustaining virus for any length of time. We found that several grassland species were capable of harboring virus for periods ranging from 1 to 24 hours, while other species were completely non-supportive of virus. At 24 hours post exposure, viral recovery on plant species ranged from 0.2% to 7% of the inocula. Interestingly monocotyledon species in general were more hospitable for VSV than were the dicotyledonous species tested. While no virus replication was observed in any plants, pastureland monocotyledon species certainly provide a significant window of VSV survivability for grasshopper infections during VSV outbreaks in North Plains grassland pastures of the western United States.