Equine infectious anemia (EIA), a disease caused by equine infectious anemia virus (EIAV), is considered an obstacle to the development of the horse industry. There is no treatment or vaccine available for EIA, and its pathogenesis, as well as the immune response against the virus, is not fully understood. Therefore, an immunohistochemistry assay was developed for the detection of viral antigens in tissues of equids naturally infected with EIAV. Sections of organs of six equids from Apodi-RN, Brazil, that tested positive for EIA by serological tests (ELISA and AGID) were fixed in 10% formalin solution and embedded in paraffin. Immunohistochemistry was performed using a polyclonal anti-EIAV antibody. EIAV antigens were observed in red spleen pulp cells and hepatic sinusoids, as well as bronchiolar and alveolar epithelial cells of the lungs and proximal and distal tubules of the kidneys. The presence of EIAV in the spleen and liver was expected due to viral tropism by macrophages, which are abundantly present in these organs. However, EIAV was also found in lung and kidney epithelial cells, indicating that the virus infects cell types other than macrophages. In conclusion, the immunohistochemical assay standardized in this study was able to detect EIAV antigens in spleen, liver, kidney and lung cells from naturally infected EIAV equids. Immunostaining observed in the spleen confirms viral tropism by mononuclear phagocytes; however, the presence of EIAV in lung and kidney epithelial cells indicates that virus may be eliminated in urine and/or oronasal secretions, suggesting new routes for viral excretion.

中文翻译：

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自然感染马匹中马传染性贫血病毒的分子检测，组织病理学分析和免疫组化特征。

马传染性贫血（EIA）是一种由马传染性贫血病毒（EIAV）引起的疾病，被认为是马业发展的障碍。目前尚无可用于EIA的治疗方法或疫苗，其发病机理以及针对病毒的免疫应答尚未得到充分了解。因此，开发了一种免疫组织化学测定法，用于检测被EIAV自然感染的马匹组织中的病毒抗原。通过血清学测试（ELISA和AGID）对EIA呈阳性的来自巴西Apodi-RN的六个马的器官切片固定在10％福尔马林溶液中，并包埋在石蜡中。使用多克隆抗EIAV抗体进行免疫组织化学。在脾脏红细胞和肝窦中观察到EIAV抗原，以及肺的细支气管和肺泡上皮细胞以及肾脏的近端和远端小管。由于巨噬细胞的病毒嗜性，预计在脾脏和肝脏中会存在EIAV，这些病毒大量存在于这些器官中。但是，在肺和肾上皮细胞中也发现了EIAV，表明该病毒感染了巨噬细胞以外的其他细胞类型。总之，本研究中标准化的免疫组织化学测定能够检测自然感染的EIAV设备的脾脏，肝，肾和肺细胞中的EIAV抗原。在脾脏中观察到的免疫染色证实了单核吞噬细胞的病毒嗜性；然而，EIAV在肺和肾上皮细胞中的存在表明病毒可能会在尿液和/或口鼻分泌物中被清除，这提示了病毒排泄的新途径。