Department of Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido, Japan.
J Vet Diagn Invest. 2024 Mar;36(2):222-228. doi: 10.1177/10406387241229724. Epub 2024 Mar 1.
Since being reported in 1979 and 2006, indirect fluorescent antibody (IFA) tests have not been reported to detect bovine viral diarrhea virus (BVDV) antibodies to our knowledge. Thus, we re-evaluated the efficacy and usefulness of IFA tests for BVDV serology. We tested 4 combinations of 2 antibody conjugates (fluorescein isothiocyanate [FITC]-conjugated rabbit IgG anti-bovine IgG; rabbit IgG F(ab') fragment anti-bovine IgG [F(ab') FITC-IgG]) and 2 washing solutions (PBS; carbonate-bicarbonate-buffered saline [CBBS]) to evaluate the specificity of an IFA test for BVDV. We compared the sensitivity of the optimal combination with virus neutralization (VN) tests and an ELISA, and compared IFA with VN titers against different genotype (subgenotype) strains. For the F(ab') FITC-IgG/CBBS combination, only 1 of the 156 (0.6%) 4-fold diluted cattle sera resulted in a nonspecific reaction; other combinations led to a much higher incidence (22.9-37.2%). For the F(ab') FITC-IgG/CBBS combination, IFA detection rates were identical (36 of 59) for BVDV1 and BVDV2 genotypes, and IFA titers against them were strongly correlated ( = 0.99). The antibody-detection rates of the IFA tests were almost identical to those of VN tests and the ELISA (κ: 0.96 and 0.89, respectively). The IFA titers against 4 strains (BVDV1a, BVDV1j, BVDV2a, and an unidentified strain) were similar, 1,024 to ≥4,096, although the VN titers were different. Thus, our IFA tests were specific and sensitive, and more useful than VN tests given that the IFA tests could evaluate the immune status of cattle using a representative strain, regardless of genotype (subgenotype).
自 1979 年和 2006 年报道以来，据我们所知，间接荧光抗体（IFA）试验尚未用于检测牛病毒性腹泻病毒（BVDV）抗体。因此，我们重新评估了 IFA 试验在 BVDV 血清学中的功效和实用性。我们测试了 2 种抗体缀合物（异硫氰酸荧光素 [FITC] 缀合的兔 IgG 抗牛 IgG；兔 IgG F(ab') 片段抗牛 IgG [F(ab') FITC-IgG]）和 2 种洗涤溶液（PBS；碳酸盐-碳酸氢盐缓冲盐水 [CBBS]）的 4 种组合，以评估 IFA 试验对 BVDV 的特异性。我们比较了最佳组合与病毒中和（VN）试验和 ELISA 的敏感性，并比较了 IFA 与针对不同基因型（亚基因型）株的 VN 滴度。对于 F(ab') FITC-IgG/CBBS 组合，只有 156 份（0.6%）4 倍稀释牛血清中 1 份产生非特异性反应；其他组合导致更高的发生率（22.9-37.2%）。对于 F(ab') FITC-IgG/CBBS 组合，IFA 对 BVDV1 和 BVDV2 基因型的检测率相同（59 个中有 36 个），并且它们的 IFA 滴度呈强相关性（ = 0.99）。IFA 试验的抗体检测率与 VN 试验和 ELISA 几乎相同（κ：0.96 和 0.89）。IFA 对 4 株（BVDV1a、BVDV1j、BVDV2a 和一株未鉴定株）的滴度相似，为 1024 至≥4096，尽管 VN 滴度不同。因此，我们的 IFA 试验具有特异性和敏感性，并且比 VN 试验更有用，因为 IFA 试验可以使用代表株评估牛的免疫状态，而与基因型（亚基因型）无关。
