Isolation and Phylogenetic Grouping of Equine Encephalosis Virus in Israel

Aharonson-Raz, Karin; Steinman, Amir; Bumbarov, Velizar; Maan, Sushila; Maan, Narender S.; Nomikou, Kyriaki; Batten, Carrie; Potgieter, Christiaan; Gottlieb, Yuval; Mertens, Peter P. C.; Klement, Eyal

doi:10.3201/eid1710.110350

Cited by 20 publications

(31 citation statements)

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“…Until 2008, EEV was thought to be confined to South Africa. However, during a febrile outbreak in horses in Israel in 2008–2009, we succeeded to isolate EEV for the first time outside of Africa and phylogenetically characterized it as a separate cluster from the South African strains but with 92% nucleotide identity to the Kaaplas South African reference strain (Aharonson‐Raz et al., ). This relatively high difference between the Israeli and the South African serotypes together with a recent serological study conducted in 2013 in Israel (Wescott et al., ) suggests that the virus is endemic in Israel, at least since 2001.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Association of Climate, Weather and Herd Immunity with the Spread of Equine Encephalosis Virus in Horses in Israel

Aharonson-Raz

Steinman

Kavkovsky

et al. 2015

Transbound Emerg Dis

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It is claimed that the distribution of Culicoides-borne viruses is highly influenced by climate. Equine encephalosis virus (EEV) is a Culicoides-borne orbivirus which affects horses and was recently found to be endemic in Israel. To test whether climate is a crucial factor in the geographical distribution of EEV, we collected blood samples from horses in Israel during the years 2002, 2007 and 2010 and tested them for the abundance of antibodies to EEV. Samples were also collected in 2011 from horses that were seronegative to the virus in 2010, to determine the rate of infection with EEV. It was found that seroprevalence fluctuated between the years and that in each year it was highest in a different climatic region. Interestingly, analysis of infection rate at the different farms showed a negative association with seroprevalence at prior observations. In addition, analysis of precipitation preceding the outbreak of EEV which occurred during 2008 revealed that an extremely dry period existed several months prior to the febrile outbreak with the average precipitation of spring 2008 being significantly lower than the average spring precipitation of the years 1997-2009. It is therefore conjectured that exposure to EEV is not climate specific. Rather, it is highly influenced by herd immunity and weather fluctuations which might change annually. This finding may have important implications for the prediction of the abundance of Culicoides-borne viruses in endemic regions.

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Section: Introductionmentioning

confidence: 99%

Analysis of the Association of Climate, Weather and Herd Immunity with the Spread of Equine Encephalosis Virus in Horses in Israel

Aharonson-Raz

Steinman

Kavkovsky

et al. 2015

Transbound Emerg Dis

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“…Only one serotype of EEV had been isolated in Israel that was similar, but not identical to the South African EEV‐3 (Aharonson‐Raz et al . ), and the method used for detection of specific antibodies was based on this isolate (Aharonson‐Raz et al . ).…”

Section: Discussionmentioning

confidence: 99%

“…These viruses were isolated on Vero cells in 2009 during the EEV outbreak in Israel, and formed a distinct group, similar to EEV‐3, but with characteristics of both south‐African serologic groups (Aharonson‐Raz et al . ). The serum neutralization test was performed as described previously (Aharonson‐Raz et al .…”

Section: Methodsmentioning

confidence: 97%

“…The Israeli EEV strains (H3, H8) (Aharonson‐Raz et al . ) were used as the neutralized viruses for the serum neutralization test. These viruses were isolated on Vero cells in 2009 during the EEV outbreak in Israel, and formed a distinct group, similar to EEV‐3, but with characteristics of both south‐African serologic groups (Aharonson‐Raz et al .…”

Section: Methodsmentioning

confidence: 99%

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Seroprevalence and risk factor analysis for exposure to equine encephalosis virus in Israel, Palestine and Jordan

Tirosh-Levy

Gelman²,

Zivotofsky³

et al. 2017

Vet Med Sci

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Equine encephalosis virus (EEV) is an orbivirus transmitted by Culicoides species. Most infected horses show mild clinical signs and mortality is usually very low. EEV is closely related and similarly transmitted to other, more pathogenic and economically important, orbiviruses such as African horse sickness virus (AHSV), bluetongue virus (BTV) and epizootic haemorrhagic disease viruses (EHDV), and may serve as an indicator for possible transmission of the latter. Israel has been reported to be endemic for EEV since 2001. This study was initiated to re‐evaluate the current seroprevalence and risk factors for EEV exposure in Israel, and to assess, for the first time, the seroprevalence of EEV in Palestine and Jordan. Three hundred and sixteen serum samples were collected from apparently healthy horses at 21 farms in Israel, 66 horses at nine farms in Palestine and 100 horses at three farms in Jordan. The presence of EEV antibodies was detected by a serum neutralization assay. Seroprevalence of EEV was 58.2% (184/316 horses) in Israel, 48.5% (32/66 horses) in Palestine and 2% (2/100 horses) in Jordan. Seroprevalence in Jordan was significantly lower than in Israel and Palestine (P < 0.001). The farm (P < 0.001) and horse age (P = 0.003) were found as significant risk factors for EEV exposure in Israel in multivariable statistical analysis. The results of this study further demonstrate that EEV is no longer limited to South Africa and is endemic in both Israel and Palestine and horses in Jordan were also exposed to this virus emphasizing the potential of pathogens to invade new ecological niches.

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“…The viral genome encodes 7 structural proteins (virus capsid proteins [VPs] 1–7) and 3 nonstructural proteins (NS1–3). On the basis of cross-neutralizing antibodies, 7 distinct serotypes of EEV (EEV-1–7) have been characterized ( 6 ). …”

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confidence: 99%