The direct-fluorescent antibody test (dFAT) is considered the “gold standard” assay to diagnose rabies. However, it is crucial to develop molecular techniques, such as RT-PCR and RT-qPCR, since many laboratories lack the needed supplies for performing complementary methods (viral isolation, for example). For this purpose, diagnostic techniques must be specific and sensitive to guarantee accuracy. This present investigation aimed to detect rabies virus (RABV) in 126 clinically suspected cattle in Brazil using different diagnostic tests [dFAT, mouse inoculation test (MIT), immunohistochemistry (IHC), RT-PCR and RT-qPCR] and to compare those results obtained under routine laboratory conditions. The results of the present investigation demonstrate that the molecular techniques are more sensitive and may detect low viral load, even though the non-homogeneous viral distribution caused a false-negative result in dFAT. We also observed a usual alteration in antigens distribution among regions of the central nervous system (CNS). By both dFAT and IHC assays, the most reliable CNS structures were thalamus and midbrain. Although this investigation demonstrated diagnostic sensitivity and specificity close to 100% in all laboratory techniques employed, a dFAT auxiliary test is required for bovine specimens, such as molecular techniques, when there are poor sampling conditions (low viral load combined with unavailability of brainstem structures).

直接荧光抗体检测（dFAT）被认为是诊断狂犬病的“金标准”检测方法。但是，开发分子技术（例如RT-PCR和RT-qPCR）至关重要，因为许多实验室缺乏执行互补方法（例如病毒分离）所需的用品。为此，诊断技术必须特定且敏感，以确保准确性。本研究旨在使用不同的诊断测试[dFAT，小鼠接种测试（MIT），免疫组织化学（IHC），RT-PCR和RT-qPCR]在巴西126例临床可疑牛中检测狂犬病毒（RABV），并比较这些结果在常规实验室条件下获得。本研究的结果表明，分子技术更加灵敏，可以检测出低病毒载量，即使病毒的非均匀分布在dFAT中造成假阴性结果。我们还观察到中枢神经系统（CNS）区域之间抗原分布的通常变化。通过dFAT和IHC分析，最可靠的CNS结构是丘脑和中脑。尽管这项研究表明在所有使用的实验室技术中诊断灵敏度和特异性均接近100％，但是当采样条件较差（病毒载量低且脑干结构不可用）时，对于分子标本等牛标本需要进行dFAT辅助测试。最可靠的中枢神经系统结构是丘脑和中脑。尽管这项研究表明在所有使用的实验室技术中诊断灵敏度和特异性均接近100％，但是当采样条件较差（病毒载量低且脑干结构不可用）时，对于分子标本等牛标本需要进行dFAT辅助测试。最可靠的中枢神经系统结构是丘脑和中脑。尽管这项研究表明在所有采用的实验室技术中诊断灵敏度和特异性均接近100％，但是当采样条件较差（病毒载量低且脑干结构不可用）时，对于分子标本等牛标本需要进行dFAT辅助测试。