长期冷冻对用于诊断马原虫性脑脊髓炎的间接荧光抗体效价的影响。
Effect of Long-Term Freezing on Indirect Fluorescent Antibody Titers for the Diagnosis of Equine Protozoal Myeloencephalitis.
作者信息
Valderrama-Martinez Claudia, Packham Andrea, Smith Woutrina, Mendoza-Flores Jorge Eduardo, Zheng Shichen, Chigerwe Munashe, Plancarte Magdalena, Aleman Monica
机构信息
Departamento de Salud Animal, Facultad de Medicina Veterinaria y Zootecnia. Universidad Nacional de, Bogotá, Colombia.
One Health Institute, School of Veterinary Medicine, University of California Davis, Davis, California, USA.
出版信息
J Vet Intern Med. 2025 Sep-Oct;39(5):e70225. doi: 10.1111/jvim.70225.
BACKGROUND
Long-term freezing storage can alter the stability of proteins, thereby compromising accurate determination of indirect fluorescent antibody test (IFAT) titers that support the diagnosis of equine protozoal myeloencephalitis.
OBJECTIVE
Assess the effect of long-term storage at -80°C on IFAT against S. neurona and N. hughesi in equine serum and cerebrospinal fluid (CSF).
SAMPLES
Paired serum and CSF (n = 46), and serum only (n = 25) samples.
METHODS
Prospective study of samples stored 6-12, 13-18, and 19-24 months. Comparing antibody titers across time points, McNemar and Wilcoxon rank tests were used for statistical analysis.
RESULTS
After long-term freezing storage for 19-24 months, N. hughesi IFAT results for CSF were significantly different compared with their fresh-testing time point (p = 0.04), but a similar difference was not observed for serum samples. No statistical differences were observed for serum or CSF samples tested for S. neurona after 6-12, 13-18, or 19-24 months compared with their original fresh testing results. However, the serum to CSF ratio cutoff of ≤ 64 in support of disease changed in 41% (19 of 46) of paired samples.
CONCLUSIONS AND CLINICAL IMPORTANCE
Freezing samples at -80°C for more than 18 months might alter test results, leading to possible changes in serum to CSF ratio calculations and affecting the interpretation of results for clinical and research purposes.
背景
长期冷冻保存会改变蛋白质的稳定性，从而影响支持马原虫性脑脊髓炎诊断的间接荧光抗体试验（IFAT）效价的准确测定。
目的
评估在-80°C长期保存对马血清和脑脊液（CSF）中针对神经孢子虫和休氏新孢子虫的IFAT的影响。
样本
配对的血清和脑脊液样本（n = 46），以及仅血清样本（n = 25）。
方法
对保存6 - 12个月、13 - 18个月和19 - 24个月的样本进行前瞻性研究。比较不同时间点的抗体效价，采用McNemar检验和Wilcoxon秩和检验进行统计分析。
结果
在-80°C长期冷冻保存19 - 24个月后，脑脊液中针对休氏新孢子虫的IFAT结果与其新鲜检测时间点相比有显著差异（p = 0.04），但血清样本未观察到类似差异。与原始新鲜检测结果相比，在6 - 12个月、13 - 18个月或19 - 24个月后检测神经孢子虫的血清或脑脊液样本未观察到统计学差异。然而，在41%（46对样本中的19对）的配对样本中，支持疾病诊断的血清与脑脊液比值截断值≤64发生了变化。
结论及临床意义
在-80°C冷冻样本超过18个月可能会改变检测结果，导致血清与脑脊液比值计算可能发生变化，并影响临床和研究目的的结果解读。
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