Abstract
This study aimed to establish immune level and protection of Ukraine vaccine against viral rabbit hemorrhagic disease (VRHD) and determine Histopathological changes among different affected ages. 10 random vaccinated adult breeding rabbits and 10 random unvaccinated weaned rabbit (5 from mother vaccinated at mid-pregnancy &5 from mother vaccinated at labor) were selected from a total of 200 rabbits (128 females, 40 males and 32 weaned) which vaccinated with Ukraine VRHDV (viral rabbit hemorrhagic disease vaccine) as seasonal vaccination routine work at 18/12/2017, blood samples were collected for obtaining their sera to determine HI titer at 16, 23, 30, 37 and 70 days post vaccination (dpv) in adult breeding rabbits, while collected from weaned rabbits at 45, 60 old age. This rabbit farm as a whole observed for natural outbreak through one year. Adult breeding rabbits showed HI titer of 240±23.851, 380±77.974, 480±47.703, 960±95.406 and 800±143.108 at 16, 23, 30, 37 and 70 dpv respectively while weaned rabbits from mother vaccinated at mid-pregnancy showed HI titer of 440±61.968 & 200±20.656 at 45 & 60 old age respectively also weaned rabbits from mother vaccinated at labor showed HI titer of 290±67.132 & 140±10.328 at 45 & 60 old age respectively. 1st Natural outbreak of RHD (rabbit hemorrhagic disease) occurred 5 months' post vaccination affecting non vaccinated weaned rabbits only, while 2nd Natural outbreak affecting both vaccinated and non-vaccinated rabbits at 9 months' post vaccination with severe mortalities. Histopathology of livers, kidneys, lungs and hearts were applied exhibiting hemorrhage, edema and inflammatory cells infiltrations in all organs with coagulative necrosis of liver and renal tubules accompanied by myocardial degeneration, these lesions varied in its severity and spreading according to affected ages. Finally, Ukraine VRHDV protect against RHD viral infection for a limited period which required to be determined in other studies.

Key words: Rabbit, viral hemorrhagic vaccine, immunity, histopathology.