Abstract
A study was performed to examine the effect of viral inoculum size on the appearance of clinical signs in equine Getah virus (GV) infection by intramuscular inoculation with 101.3 to 106.3 TCID50 of the MI-110 strain in 6 experimental horses. When inoculated with more than 103.3 TCID50 of the virus, every horse developed pyrexia, edema in the hind legs, serous nasal discharge, lymphopenia and viremia in the relatively early stage of disease. On the other hand, enlargement of the submandibular lymph node was observed only in horses inoculated with 105.3 and 106.3 TCID50 of the virus, while typical eruptions were developed in every horse inoculated with 104.3 TCID50 or less. These results demonstrated that the appearance of clinical signs in equine GV infection was dependent on viral inoculum size. Besides, it was assumed to be rare chance that eruptions and enlargement of the submandibular lymph node were developed simultaneously in a horse.
