SUSCEPTIBILITY OF HARES AND RABBITS TO A BELGIAN ISOLATE OF EUROPEAN BROWN HARE SYNDROME VIRUS

Signs and pathologic changes of European brown hare syndrome (EBHS) we re reproduced in four hares (Lepus europaeus) after experimental inocu lation of a liver suspension from hares from Belgium, which naturally died of EBHS. Virus particles were demonstrated by electron microscopy in the liver of an experimentally infected hare. They were spherical with a diameter of 28 to 30 nm. After density gradient centrifugation, virus particles were detected in the density zone of 1.34 g/ml. Based on immunoelectron microscopy with a convalescent serum, we identified the virus as the cause of EBHS. Clinical signs were not produced in t hree seronegative domestic rabbits after subcutaneous inoculation of t he EBHS virus. Although low levels of antibodies against EBHS virus we re found in the serum of these three rabbits 4 weeks after the inocula tion of EBHS virus, the rabbits were not protected when challenged wit h viral hemorrhagic disease (VHD) virus. The different pathogenicity o f the Belgian EBHS and VHD virus isolates in rabbits and the lack of p rotection in rabbits with circulating EBHS virus antibodies against a challenge with VHD virus indicates that both Belgian virus isolates fo rm two different virus populations.