Adair B M, McNulty M S, Todd D, Connor T J, Burns K
Department of Agriculture, Veterinary Research Laboratories, Stormont, Belfast, Northern Ireland.
Avian Pathol. 1989 Jan;18(1):175-92. doi: 10.1080/03079458908418589.
A quantitative single-well ELISA for estimation of Newcastle disease (ND) virus antibodies in chickens and turkeys was developed using purified antigen from PMV-1/Chicken/Ulster 2C/71. The test was standardised using sera from 20-week-old chickens or 20- 30-week-old turkeys. Absorbance values for negative sera in chickens increased with the age of the birds but overall was lower than the cut-off for the test. ND haemagglutination inhibition (HI) positive field sera were always positive by ELISA and the mean was significantly higher than that of the negative population. Standard antisera to four of seven of the other PMV serotypes (including PMV-3) gave positive reactions in ELISA and three were also positive at low level by PMV-1 HI test. Absorbance values remained negative in turkeys given two inoculations of PMV-3 vaccine in spite of good PMV-3 HI responses. Doubling dilutions of chicken and turkey sera were tested by ELISA and end-point titres calculated. Standard curves relating ELISA titre and absorbance of each sample at 1/100 dilution were constructed and used to determine titres of test samples from single well absorbance values. A significant positive correlation between ELISA titre and HI titre for chicken and turkey sera was demonstrated. Sensitivity of the test was investigated using birds experimentally infected with PMV-1/Chicken/Ulster 2C/71 or a pigeon PMV-1 isolate. Seroconversion was detected at the same time by ELISA and HI. In experiments to estimate the ELISA titre required to protect birds against virulent ND, five groups of chickens were vaccinated twice with one of four commercial ND vaccines (three inactivated; one live) on two occasions and challenged with a virulent ND strain (PMV-1/ Chicken/Antrim/73). Two of the groups vaccinated with inactivated vaccines were protected against challenge. In another group also given inactivated vaccine, clinical signs were seen in one bird and ELISA proved a better indicator of immune status than HI. In the groups given living vaccine, no signs of ND were seen and ELISA indicated a much higher level of vaccinal antibody than HI test. In turkeys given two inoculations with inactivated vaccine, antibody levels were boosted to acceptable levels by ELISA and HI indicating that vaccinal antibody levels were adequate.
利用来自PMV - 1/鸡/阿尔斯特2C/71的纯化抗原，开发了一种用于定量检测鸡和火鸡新城疫（ND）病毒抗体的单孔ELISA方法。该检测方法使用20周龄鸡或20 - 30周龄火鸡的血清进行标准化。鸡的阴性血清吸光度值随鸡龄增加，但总体低于检测的临界值。ND血凝抑制（HI）阳性的田间血清在ELISA检测中始终呈阳性，其平均值显著高于阴性群体。针对其他七种PMV血清型中的四种（包括PMV - 3）的标准抗血清在ELISA检测中呈阳性反应，其中三种在PMV - 1 HI检测中也呈低水平阳性。尽管火鸡对PMV - 3疫苗有良好的HI反应，但在接种两次PMV - 3疫苗后，ELISA检测吸光度值仍为阴性。通过ELISA检测鸡和火鸡血清的倍比稀释液，并计算终点滴度。构建了1/100稀释度下各样本的ELISA滴度与吸光度的标准曲线，并用于根据单孔吸光度值确定检测样本的滴度。结果表明，鸡和火鸡血清的ELISA滴度与HI滴度之间存在显著正相关。使用经PMV - 1/鸡/阿尔斯特2C/71或鸽源PMV - 1分离株实验感染的禽类研究了该检测方法的敏感性。ELISA和HI同时检测到血清转化。在评估保护禽类免受强毒ND所需的ELISA滴度的实验中，五组鸡分两次用四种商业ND疫苗（三种灭活疫苗；一种活疫苗）之一进行免疫接种，并接种强毒ND毒株（PMV - 1/鸡/安特里姆/73）进行攻毒。两组接种灭活疫苗的鸡受到保护，未被攻毒。在另一组同样接种灭活疫苗的鸡中，有一只出现临床症状，ELISA检测结果证明其比HI检测更能准确反映免疫状态。在接种活疫苗的组中，未出现ND症状，ELISA检测显示疫苗抗体水平比HI检测高得多。在接种两次灭活疫苗的火鸡中，ELISA和HI检测均显示抗体水平提高到了可接受水平，表明疫苗抗体水平足够。
