Sequential pathologic changes and viral distribution in rabbits experimentally infected with new Korean strain of rabbit hemorrhagic disease virus (RHDVa)

Abstract

Department of Clinical Laboratory Science, Semyung University, Jecheon 390-711, Korea(Received: May 11, 2012; Revised: June 20, 2012; Accepted: June 21, 2012)Abstract : Rabbit hemorrhagic disease is a highly acute and fatal viral disease caused by rabbit hemorrhagicdisease virus (RHDV). Since first outbreak in Korea 1987, RHDV has been continually affected in thecountry, but the pattern of outbreak seem to be changed. In this study, to understand the pathogenesis ofthe new RHDVa serotype, we therefore carried out to inoculate RHDVa to rabbits, and to examine thesequential histopathologic changes and viral distribution. Macroscopically, various sized dark red or whitespots or appearance were observed in the liver, lung, kidney uterus and ureter. In euhanized rabbits,significant pathologic findings such as infiltration of heterophils and mononuclear cells were observed at24 hours after inoculation (HAI), and these were sequentially extended periportal to centrilobular area.However, in dead rabbits, severe hepatic degeneration and/or necrosis with relatively weak inflammatoryresponses were observed. RHDV antigens began to detect in liver, spleen, and lung from 12 HAI by PCR.Immunohistochemically, RHDV positive cells were seen in only liver from 24 HAI, and the degree ofimmunogen reactivity was stronger in dead rabbits than in euthanized ones. In conclusion, RHDVa causedthe subacute or chronic infection accompanying low mortality and moderate to severe inflammatory reactionin rabbits, suggesting the possibility that RHD could become endemic.Keywords : chronic infection, histopathologic changes, new RHDVa serotype, rabbit hemorrhagic disease,viral distribution