Haddad E E, Whitfill C E, Avakian A P, Ricks C A, Andrews P D, Thoma J A, Wakenell P S
EMBREX Inc., Research Triangle Park, NC 27560, USA.
Avian Dis. 1997 Oct-Dec;41(4):882-9.
Two experiments were conducted to test the efficacy of a novel infectious bursal disease virus (IBDV) vaccine in broiler chickens with maternal IBDV immunity. The IBDV vaccine was formulated by mixing IBDV strain 2512 with bursal disease antibodies (BDA) to produce the IBDV-BDA complex vaccine. In Expt. I, 1-day-old Cobb x Cobb broiler chickens were vaccinated subcutaneously with either IBDV-BDA or commercial live intermediate IBDV vaccine (vaccine A) or were left unvaccinated. In Expt. 2, the vaccine A group was not included; instead, IBDV strain 2512 was included. Chickens were maintained in isolation houses. On day 28 (Expt. 1) and day 32 (Expt. 2) of age, chickens from each group were challenged with a standard USDA IBDV (STC strain) challenge. Challenged and unchallenged chickens were evaluated for their bursa/body weight ratios and antibody titers 3 days post-challenge. Bursae collected from Expt. 2 were examined histologically to evaluate bursal lesions and confirm gross examination. None of the unvaccinated chickens was protected against the challenge virus as evidenced by the presence of acute bursal lesions (edema/hemorrhage). All chickens receiving the IBDV-BDA complex or the IBDV strain 2512 (Expt. 2) were protected from the challenge virus as evidenced by no acute bursal lesions. Additionally, chickens receiving the IBDV-BDA complex vaccine or the IBDV strain 2512 had antibody titers to IBDV, indication the presence of an active immune response. In Expt. 1, chickens vaccinated with vaccine A and challenged had bursal lesions similar to those observed in the unvaccinated, challenged chickens. These chickens also showed no indication of active immunity against the virus. These results suggest that the 1-day-of-age-administered IBDV-BDA complex vaccine can induce active immunity and protection against a standard IBDV challenge in the face of variable levels of maternal IBDV immunity.
进行了两项实验，以测试一种新型传染性法氏囊病病毒（IBDV）疫苗在具有母源IBDV免疫力的肉鸡中的效力。IBDV疫苗是通过将IBDV 2512株与法氏囊病抗体（BDA）混合配制而成，以生产IBDV-BDA复合疫苗。在实验I中，1日龄的科宝×科宝肉鸡皮下接种IBDV-BDA或市售活的中等毒力IBDV疫苗（疫苗A），或不进行接种。在实验2中，未设置疫苗A组；取而代之的是加入了IBDV 2512株。鸡饲养在隔离舍中。在28日龄（实验1）和32日龄（实验2）时，每组鸡用美国农业部标准IBDV（STC株）进行攻毒。在攻毒后3天，对攻毒和未攻毒的鸡评估其法氏囊/体重比和抗体滴度。从实验2中收集的法氏囊进行组织学检查，以评估法氏囊病变并确认大体检查结果。未接种疫苗的鸡均未对攻毒病毒产生保护，表现为存在急性法氏囊病变（水肿/出血）。所有接种IBDV-BDA复合物或IBDV 2512株（实验2）的鸡均受到攻毒病毒的保护，表现为无急性法氏囊病变。此外，接种IBDV-BDA复合疫苗或IBDV 2512株的鸡具有IBDV抗体滴度，表明存在活跃的免疫反应。在实验1中，接种疫苗A并攻毒的鸡出现的法氏囊病变与未接种疫苗且攻毒的鸡所观察到的病变相似。这些鸡也未显示出对该病毒的主动免疫迹象。这些结果表明，1日龄接种的IBDV-BDA复合疫苗在母源IBDV免疫力水平不同的情况下，能够诱导主动免疫并提供针对标准IBDV攻毒的保护。
