Felten Sandra, Weider Karola, Doenges Stephanie, Gruendl Stefanie, Matiasek Kaspar, Hermanns Walter, Mueller Elisabeth, Matiasek Lara, Fischer Andrea, Weber Karin, Hirschberger Johannes, Wess Gerhard, Hartmann Katrin
1 Clinic of Small Animal Medicine, Ludwig-Maximilians-University Munich, Munich, Germany.
2 LABOKLIN GmbH & Co KG, Bad Kissingen, Germany.
J Feline Med Surg. 2017 Apr;19(4):321-335. doi: 10.1177/1098612X15623824. Epub 2016 Jul 10.
Objectives Feline infectious peritonitis (FIP) is an important cause of death in the cat population worldwide. The ante-mortem diagnosis of FIP in clinical cases is still challenging. In cats without effusion, a definitive diagnosis can only be achieved post mortem or with invasive methods. The aim of this study was to evaluate the use of a combined reverse transcriptase nested polymerase chain reaction (RT-nPCR) and sequencing approach in the diagnosis of FIP, detecting mutations at two different nucleotide positions within the spike (S) gene. Methods The study population consisted of 64 cats with confirmed FIP and 63 cats in which FIP was initially suspected due to similar clinical or laboratory signs, but that were definitively diagnosed with another disease. Serum/plasma and/or effusion samples of these cats were examined for feline coronavirus (FCoV) RNA by RT-nPCR and, if positive, PCR products were sequenced for nucleotide transitions within the S gene. Results Specificity of RT-nPCR was 100% in all materials (95% confidence interval [CI] in serum/plasma 83.9-100.0; 95% CI in effusion 93.0-100.0). The specificity of the sequencing step could not be determined as none of the cats of the control group tested positive for FCoV RNA. Sensitivity of the 'combined RT-nPCR and sequencing approach' was 6.5% (95% CI 0.8-21.4) in serum/plasma and 65.3% (95% CI 50.4-78.3) in effusion. Conclusions and relevance A positive result is highly indicative of the presence of FIP, but as none of the control cats tested positive by RT-nPCR, it was not possible to confirm that the FCoV mutant described can only be found in cats with FIP. Further studies are necessary to evaluate the usefulness of the sequencing step including FCoV-RNA-positive cats with and without FIP. A negative result cannot be used to exclude the disease, especially when only serum/plasma samples are available.
目的 猫传染性腹膜炎（FIP）是全球猫种群中一个重要的死亡原因。临床病例中FIP的生前诊断仍然具有挑战性。在没有积液的猫中，只有在死后或采用侵入性方法才能做出明确诊断。本研究的目的是评估联合逆转录巢式聚合酶链反应（RT-nPCR）和测序方法在FIP诊断中的应用，检测刺突（S）基因内两个不同核苷酸位置的突变。方法 研究群体包括64只确诊为FIP的猫和63只最初因相似临床或实验室体征而怀疑患有FIP，但最终被诊断为其他疾病的猫。通过RT-nPCR检测这些猫的血清/血浆和/或积液样本中的猫冠状病毒（FCoV）RNA，若呈阳性，则对PCR产物进行测序以检测S基因内的核苷酸转换。结果 RT-nPCR在所有材料中的特异性均为100%（血清/血浆中的95%置信区间[CI]为83.9 - 100.0；积液中的95%CI为93.0 - 100.0）。由于对照组中没有猫的FCoV RNA检测呈阳性，所以无法确定测序步骤的特异性。“联合RT-nPCR和测序方法”在血清/血浆中的敏感性为6.5%（95%CI为0.8 - 21.4），在积液中的敏感性为65.3%（95%CI为50.4 - 78.3）。结论及意义 阳性结果高度提示FIP的存在，但由于对照组中没有猫通过RT-nPCR检测呈阳性，所以无法证实所描述的FCoV突变体仅存在于患有FIP的猫中。需要进一步研究来评估测序步骤的有用性，包括对有和没有FIP的FCoV - RNA阳性猫进行研究。阴性结果不能用于排除该疾病，尤其是当只有血清/血浆样本可用时。
