The results also indicated that the virulence of the most ibdv field collected in recent years was between the typical very virulent and standard virulent strains . a very virulent strain gx8 / 99 of ibdv was studied for its mortality in spf chickens and commercial egg - type chickens at different age inoculated with bursal suspension of 20 - 2000 eld50 in repeated experiments 选择致病性最强的来自广西的gx8 99株，在对法氏囊悬液中病毒用鸡胚半数致死量( eld _ ( 50 ) )定量测定后，在不同年龄的spf鸡和商品代蛋用型坞多次重复地比较研究了该毒株的致病性。
