Location: Arthropod-borne Animal Diseases ResearchTitle: Susceptibility of Culicoides sonorensis to infection with EHDV-6 (Indiana) and comparison to EHDV-1 and -2) Author
Submitted to: Wildlife Disease Association Annual Meeting
Publication Type: Abstract only
Publication Acceptance Date: 6/13/2011
Publication Date: 8/14/2011
Citation: Ruder, M.G., Carter, D.L., Allison, A.B., Drolet, B.S., Stallknecht, D.E., Howerth, E.W., Mead, D.G. 2011. Susceptibility of Culicoides sonorensis to infection with EHDV-6 (Indiana) and comparison to EHDV-1 and -2. Wildlife Disease Association Annual Meeting. p. 138. Interpretive Summary:
Technical Abstract: Epizootic hemorrhagic disease virus (EHDV) serotypes 1 and 2 are endemic to North America. Although Culicoides sonorensis is considered to be the primary vector, outbreaks have occurred in regions of the US where C. sonorensis are not typically found. In 2006, EHDV-6, a serotype not previously documented in North America, was isolated from a dead white-tailed deer (WTD) in Indiana. Although additional virus isolations from multiple states in subsequent years suggest this virus may be endemic, the vector of EHDV-6 remains unknown. To evaluate C. sonorensis as a potential vector of serotype 6 and compare its susceptibility to infection with EHDV-1 and -2, we conducted experimental infections of colonized C. sonorensis with all three serotypes. Midges were fed WTD blood spiked with EHDV-1, -2, or -6 through a parafilm membrane and were then incubated at 25 °C. Beginning day 0 through 14 of incubation, = 10 midges were processed for virus isolation and titration every 48 hours. Midges with a virus titer of =102.7 TCID50/midge were considered potentially competent vectors. From day 4 through 14 of incubation, the percent of virus-positive midges was 11% (17/156), 85% (70/82), and 75% (87/116) for EHDV-6, -1, and -2, respectively. The percent of midges with a virus titer of =102.7 TCID50 was 4% (6/156), 60% (49/82), and 36% (42/116) for EHDV-6, -1, and -2, respectively. These results indicate that while C. sonorensis is susceptible to infection with EHDV-6, the rate of infection and replication to high titer is low compared to EHDV-1 and -2. The possibility that other Culicoides species are involved in EHDV-6 transmission should be explored.