van den Hurk J V
Veterinary Infectious Disease Organization, Saskatoon, Saskatchewan, Canada.
Avian Dis. 1990 Jan-Mar;34(1):26-35.
Avirulent hemorrhagic enteritis virus (HEV-A) propagated in turkey leukocyte cell culture was tested as a vaccine to prevent hemorrhagic enteritis (HE) in turkeys in experimental and field trials. Immunization of turkeys with live HEV-A resulted in protection against a challenge with virulent HEV (HEV-V) as measured by the serological response and the absence of clinical disease and HEV antigen in spleens. In field trials, 19 out of 20 flocks seroconverted within 21 days after vaccination with live HEV-A distributed in the drinking water. The average immune response of the turkeys in these flocks was 96%. Most importantly, neither clinical HE nor other adverse effects caused by HEV-A vaccination were observed in any of the vaccinated flocks. Because maternal antibodies can interfere with the immune response to the vaccine, the optimum time for vaccination was determined. Using an established half-life value of 4.25 days for turkey antibody, and knowing the enzyme-linked immunosorbent assay titer of the maternal antibodies and age of the turkey, the time of vaccination could be calculated taking into account that maternal antibody titers should be lower than 40 to vaccinate the turkeys successfully and induce protection. In vivo tests with HEV-A preparations confirmed the replication of the virus in turkey leukocyte cultures and the potential to pass it in culture. Furthermore, in vivo analysis showed that most infectious virus was associated with preparations of the nonadherent cell population, confirming the results obtained by in vitro analysis. The potency of HEV-A preparations was dependent on the production method and varied from an average of 570 to 8135 doses per ml.
在火鸡白细胞细胞培养物中繁殖的无毒出血性肠炎病毒（HEV-A），在实验和田间试验中作为预防火鸡出血性肠炎（HE）的疫苗进行了测试。用活的HEV-A免疫火鸡，通过血清学反应以及脾脏中无临床疾病和HEV抗原，结果显示对强毒HEV（HEV-V）攻击具有保护作用。在田间试验中，20个鸡群中有19个在通过饮水接种活HEV-A后21天内出现血清转化。这些鸡群中火鸡的平均免疫反应为96%。最重要的是，在任何接种鸡群中均未观察到临床HE或HEV-A疫苗接种引起的其他不良反应。由于母源抗体可干扰对疫苗的免疫反应，因此确定了最佳接种时间。利用已确定的火鸡抗体半衰期值4.25天，并了解母源抗体的酶联免疫吸附测定效价和火鸡年龄，考虑到母源抗体效价应低于40才能成功接种火鸡并诱导保护作用，可计算出接种时间。用HEV-A制剂进行的体内试验证实了该病毒在火鸡白细胞培养物中的复制以及在培养物中传代的可能性。此外，体内分析表明，大多数感染性病毒与非贴壁细胞群体的制剂有关，这证实了体外分析获得的结果。HEV-A制剂的效力取决于生产方法，每毫升平均剂量从570到8135剂不等。
