Isolating the first strain of epizootic hemorrhagic disease virus serotype 2 (EHDV-2) in mainland China.

Epizootic hemorrhagic disease virus (EHDV) belongs to the genus Orbivirus of Sedoreoviridae, and is the pathogen of epizootic hemorrhagic disease (EHD) which is lethal for wild white-tailed deer and sometimes cattle. Seven confirmed (i.e. EHDV-1, 2, 4-8) and two putative novel serotypes of EHDV have so far been identified worldwide. In Asia, the strains of serotype 2 are regarded as the most virulent. Although all serotypes except for serotypes 2 and 4 have been isolated in mainland China, no disease has been reported since 1985. However, an EHDV-2 strain was isolated from Culicoides collected on the China-Laos-Myanmar border in Jun 2024, and identified by phylogenetic analysis. This strain presented equivalent virulence with Ibaraki strain CSIRO_439 in bovine aortic endothelial cells (BAEC), therefore becomes a warning of EHD outbreak on the China-Laos-Myanmar border.