Khin Shwe Thiri Maung Maung, Jafar Sheikhi Mohammad, Ju Minglin, Murakoshi Fumi, Furuya Tetsuya
Cooperative Division of Veterinary Sciences, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan.
Cooperative Division of Veterinary Sciences, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan; Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan.
J Virol Methods. 2025 Dec;338:115216. doi: 10.1016/j.jviromet.2025.115216. Epub 2025 Jul 1.
Feline morbillivirus (FeMV) is a globally emerging virus that has been linked to chronic kidney disease (CKD) in infected cats. Immunological assays, such as enzyme-linked immunosorbent assay (ELISA), are important for studying the virus and monitoring its prevalence. A study using rabbit antiserum demonstrated antigenic cross-reactivity between nucleocapsid (N) proteins of FeMV and canine distemper virus (CDV), suggesting not only the risk of false-positive anti-FeMV antibody detection in ELISAs but also potentially false-positive FeMV antigen detection in Western blotting. To examine whether such cross-reactivity occurs in tests using cat plasma samples, we developed ELISAs using affinity-purified recombinant N proteins of FeMV and CDV with expression in Escherichia coli and tested 100 cat plasma samples collected from veterinary clinics in Japan. Twenty samples were found to be positive for anti-FeMV antibodies, while 6 were positive for anti-CDV antibodies. All these latter 6 samples were double-positive for anti-FeMV antibodies. Western blotting with the purified proteins confirmed the specificity of these antibodies to their target viral antigens. A reverse transcription-quantitative PCR assay with a detection limit of 100 copies failed to detect CDV genomic RNA in these 6 double-positive samples. These results strongly suggest the cross-reactivity between anti-FeMV N protein antibodies in cat plasma samples and the CDV N protein. This antigenic cross-reactivity should be considered in future studies using immunological methods employing FeMV or CDV N proteins, or antibodies targeting them.
猫瘟病毒（FeMV）是一种在全球范围内新出现的病毒，已被证实与受感染猫的慢性肾病（CKD）有关。免疫分析方法，如酶联免疫吸附测定（ELISA），对于研究该病毒及其流行情况监测至关重要。一项使用兔抗血清的研究表明，FeMV的核衣壳（N）蛋白与犬瘟热病毒（CDV）之间存在抗原交叉反应，这不仅提示了在ELISA中存在抗FeMV抗体假阳性检测的风险，还可能在蛋白质印迹法中出现FeMV抗原假阳性检测。为了研究在使用猫血浆样本的检测中是否会发生这种交叉反应，我们利用在大肠杆菌中表达的亲和纯化的FeMV和CDV重组N蛋白开发了ELISA，并检测了从日本兽医诊所收集的100份猫血浆样本。发现20份样本抗FeMV抗体呈阳性，6份样本抗CDV抗体呈阳性。后6份样本均同时抗FeMV抗体呈双阳性。用纯化蛋白进行的蛋白质印迹法证实了这些抗体对其靶病毒抗原的特异性。检测限为100拷贝的逆转录定量PCR检测未能在这6份双阳性样本中检测到CDV基因组RNA。这些结果有力地表明了猫血浆样本中抗FeMV N蛋白抗体与CDV N蛋白之间的交叉反应。在未来使用FeMV或CDV N蛋白或针对它们的抗体的免疫方法研究中，应考虑这种抗原交叉反应。
