Host and Potential Vector Susceptibility to an Emerging Orbivirus in the United States (original) (raw)
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Viruses
We report the detection and gene coding sequences of three novel Orbivirus species found in six dead farmed white-tailed deer in the United States. Phylogenetic analyses indicate that the new orbiviruses are genetically closely related to the Guangxi, Mobuck, Peruvian horse sickness, and Yunnan orbiviruses, which are thought to be solely borne by mosquitos. However, four of the six viruses analyzed in this work were found as co-infecting agents along with a known cervid pathogen, epizootic hemorrhagic disease virus-2 (EHDV-2), raising questions as to whether the new viruses are primary pathogens or secondary pathogens that exacerbate EHDV-2 infections. Moreover, EHDV-2 is known to be a Culicoides-borne virus, raising additional questions as to whether Culicoides species can also serve as vectors for the novel orbiviruses, if mosquitoes can vector EHDV-2, or whether the deer were infected through separate bites by the insects. Our findings expand knowledge of the possible viral patho...
Viruses
Epizootic hemorrhagic disease viruses (EHDVs) are arboviral pathogens of white-tailed deer and other wild and domestic ruminants in North America. Transmitted by various species of Culicoides, EHDVs circulate wherever competent vectors and susceptible ruminant host populations co-exist. The impact of variation in the level and duration of EHDV viremia in white-tailed deer (Odocoileus virginianus) on Culicoides infection prevalence is not well characterized. Here we examined how infection prevalence in a confirmed North American vector of EHDV-2 (Culicoides sonorensis) varies in response to fluctuations in deer viremia. To accomplish this, five white-tailed deer were experimentally infected with EHDV-2 and colonized C. sonorensis were allowed to feed on deer at 3, 5, 7, 10, 12, 14, 18, and 24 days post infection (dpi). Viremia profiles in deer were determined by virus isolation and titration at the same time points. Blood-fed Culicoides were assayed for virus after a 10-day incubatio...
Epizootic hemorrhagic disease virus serotype 6 experimentation on adult cattle
Research in Veterinary Science, 2013
Brief Communication Epizootic hemorrhagic disease (EHD) is an infectious, noncontagious viral disease transmitted by insects of the genus Culicoides; it affects wild and domestic ruminants, primarily white-tailed deer (Odocoileus virginianus) and cattle 6 (https://goo.gl/U1JHsf). The disease is caused by species Epizootic hemorrhagic disease virus (EHDV; genus Orbivirus, family Reoviridae). It is a double-stranded RNA virus with a linear genome of 10 segments, coding 7 structural (VP1-VP7) and 3 or 4 nonstructural (NS1-NS4) proteins. It shares many morphologic and structural characteristics with the other members of the genus, such as bluetongue virus (BTV), African horse sickness virus, and equine encephalosis virus 4 (https://goo.gl/U1JHsf). Like BTV, the primary determinant of serotype specificity is the outer capsid VP2 protein; at least 7 distinct serotypes have been identified (https://goo.gl/q3QzbL). EHDV has been isolated from cattle worldwide, including Africa, North America, Australia, Japan, and, during the last decade, the Mediterranean basin. 6 Severe clinical signs also have been observed in cattle infected by the Ibaraki strain (EHDV-2) in Japan 5 and EHDV-6, viruses similar to EHDV-6/ EHDV-318 in the countries of the Mediterranean basin. 6,9 Many cases of EHD were observed in the United States in cattle in the summer and fall of 2012 caused by the North American serotypes EHDV-1, EHDV-2, and EHDV-6. 7 In Israel, EHD was suspected in 1951, 3 but was first confirmed as an EHDV-7 outbreak in 2006. 11 The disease was reported in 83 dairy herds, each comprising 380 cows on average, and 22 beef herds. 2 Observed clinical signs-not all in any individual animal-included reduced milk production, anorexia, reduced rumination, fever, weakness, clear-to-purulent nasal discharge, drooling, nasal and labial redness with scaling, tongue swelling, cyanosis and erosions, conjunctival 726826V DIXXX10.
2012
Background: Culicoides sonorensis (Diptera: Ceratopogonidae) is a vector of epizootic hemorrhagic disease virus (EHDV) serotypes 1 and 2 in North America, where these viruses are well-known pathogens of white-tailed deer (WTD) and other wild ruminants. Although historically rare, reports of clinical EHDV infection in cattle have increased in some parts of the world over the past decade. In 2006, an EHDV-7 epizootic in cattle resulted in economic loss for the Israeli dairy industry. White-tailed deer are susceptible to EHDV-7 infection and disease; however, this serotype is exotic to the US and the susceptibility of C. sonorensis to this cattle-virulent EHDV is not known. The objective of the study was to determine if C. sonorensis is susceptible to EHDV-7 infection and is a competent vector. Methods: To evaluate the susceptibility of C. sonorensis, midges were fed on EHDV-7 infected WTD, held at 22 ± 1°C, and processed individually for virus isolation and titration on 4-16 days post feeding (dpf). Midges with a virus titer of ≥10 2.7 median tissue culture infective doses (TCID 50)/midge were considered potentially competent. To determine if infected C. sonorensis were capable of transmitting EHDV-7 to a host, a susceptible WTD was then fed on by a group of 14-16 dpf midges. Results: From 4-16 dpf, 45% (156/350) of midges that fed on WTD with high titer viremia (>10 7 TCID 50 /ml) were virus isolation-positive, and starting from 10-16 dpf, 32% (35/109) of these virus isolation-positive midges were potentially competent (≥10 2.7 TCID 50 /midge). Midges that fed on infected deer transmitted the virus to a susceptible WTD at 14-16 dpf. The WTD developed viremia and severe clinical disease. Conclusion: This study demonstrates that C. sonorensis is susceptible to EHDV-7 infection and can transmit the virus to susceptible WTD, thus, C. sonorensis should be considered a potential vector of EHDV-7. Together with previous work, this study demonstrates that North America has a susceptible ruminant and vector host for this exotic, cattle-virulent strain of EHDV-7.
Arquivo Brasileiro de Medicina Veterinária e Zootecnia, 2019
Epizootic hemorrhagic disease viruses (EHDV) are dsRNA arboviruses transmitted by biting midges of the genus Culicoides that cause disease in domestic and wild ruminants. Epizootic hemorrhagic disease (EHD) is considered the most important infectious disease of white tailed deer (WTD) in North America, some studies in Northeast Mexico reported EHDV-seropositive WTD and EHDV-infected Culicoides vectors. The increasing population of WTD that share habitat with livestock in Northeast México highlights the importance of EHD for the livestock industry in the transboundary region with the U.S. One hundred and twenty two samples from WTD in Tamaulipas state, Mexico were tested by ELISA and RT-PCR for EHDV antibodies and nucleic acid, respectively. Twelve animals were seropositive to ELISA and eleven animals were positive by RT-PCR. This is the first report of EHDV nucleic acid detection in WTD from Mexico. It is hypothesized that applying the transboundary disease approach to interdiscipli...
Viruses
We report an outbreak of a novel reassortant epizootic hemorrhagic disease virus serotype 6 (EHDV-6) in white-tailed deer (WTD) on a Florida farm in 2019. At necropsy, most animals exhibited hemorrhagic lesions in the lung and heart, and congestion in the lung, liver, and spleen. Histopathology revealed multi-organ hemorrhage and congestion, and renal tubular necrosis. Tissues were screened by RT-qPCR and all animals tested positive for EHDV. Tissues were processed for virus isolation and next-generation sequencing was performed on cDNA libraries generated from the RNA extracts of cultures displaying cytopathic effects. Six isolates yielded nearly identical complete genome sequences of a novel U.S. EHDV-6 strain. Genetic and phylogenetic analyses revealed the novel strain to be most closely related to a reassortant EHDV-6 strain isolated from cattle in Trinidad and both strains received segment 4 from an Australian EHDV-2 strain. The novel U.S. EHDV-6 strain is unique in that it acq...