Araújo J P, Montassier H J, Pinto A A
Departamento de Microbiologia e Imunologia, Universidade Estadual Paulista, Distrito de Rubiäo Jr Botucatu-SP, Brazil.
Am J Vet Res. 1996 Jun;57(6):840-3.
To develop and apply the liquid-phase blocking sandwich ELISA (BLOCKING-ELISA) for the quantification of antibodies against foot-and-mouth disease virus (FMDV) strains O1 Campos, A24 Cruzeiro, and C3 Indaial. DESIGN--Antibody quantification.
158 water buffalo from various premises of Sao Paulo State-Brazil. The sera were collected either from systemically vaccinated or nonvaccinated animals.
The basic reagents of BLOCKING-ELISA (capture and detector antibodies, virus antigens, and conjugate) were prepared and the reaction was optimized and standardized to quantify water buffalo antibodies against FMDV. An alternative procedure based on mathematical interpolation was adopted to estimate more precisely the antibody 50% competition titers in the BLOCKING-ELISA. These titers were compared with the virus-neutralization test (VNT) titers to determine the correlation between these techniques. The percentages of agreement, cutoff points, and reproducibility also were determined.
The antibody titers obtained in the BLOCKING-ELISA had high positive correlation coefficients with VNT, reaching values of 0.90 for O1 Campos and C3 Indaial, and 0.82 for the A24 Cruzeiro (P < 0.0005). The cutoff points obtained by use of the copositivity and conegativity curves allowed determination of high levels of agreement between BLOCKING-ELISA and VNT antibody titers against the 3 FMDV strains analyzed.
The results characterized by high correlation coefficients, levels of agreement, and reproducibility indicate that the BLOCKING-ELISA may replace the conventional VNT for detection and quantification of antibodies from water buffalo sera to FMDV.
开发并应用液相阻断夹心酶联免疫吸附测定法（BLOCKING-ELISA）来定量检测针对口蹄疫病毒（FMDV）O1坎波斯株、A24克鲁塞罗株和C3因代亚尔株的抗体。设计——抗体定量。
来自巴西圣保罗州不同养殖场的158头水牛。血清采集自经系统疫苗接种或未接种疫苗的动物。
制备BLOCKING-ELISA的基本试剂（捕获抗体和检测抗体、病毒抗原及缀合物），并对反应进行优化和标准化，以定量水牛针对FMDV的抗体。采用基于数学插值的替代程序，更精确地估计BLOCKING-ELISA中的抗体50%竞争效价。将这些效价与病毒中和试验（VNT）效价进行比较，以确定这些技术之间的相关性。还确定了一致性百分比、临界值和重现性。
BLOCKING-ELISA中获得的抗体效价与VNT具有高度正相关系数，O1坎波斯株和C3因代亚尔株达到0.90，A24克鲁塞罗株达到0.82（P<0.0005）。通过共阳性和共阴性曲线获得的临界值，能够确定BLOCKING-ELISA与VNT针对所分析的3种FMDV株的抗体效价之间具有高度一致性。
以高相关系数、一致性水平和重现性为特征的结果表明，BLOCKING-ELISA可替代传统的VNT，用于检测和定量水牛血清中针对FMDV的抗体。
