Boadella Mariana, Gortázar Christian
IREC (CSIC-UCLM-JCCM), Ronda de Toledo s/n, 13071 Ciudad Real, Spain.
BMC Res Notes. 2011 Nov 16;4:498. doi: 10.1186/1756-0500-4-498.
Monitoring wildlife diseases is needed to identify changes in disease occurrence. Wildlife blood samples are valuable for this purpose but are often gathered haemolysed. To maximise information, sera often go through repeated analysis and freeze-thaw cycles. Herein, we used samples of clean and haemolysed Eurasian wild boar (Sus scrofa) serum stored at -20°C and thawed up to five times to study the effects of both treatments on the outcome of a commercial ELISA test for the detection of antibodies against Suid Herpesvirus 1 (ADV).
The estimated prevalence of antibodies against ADV was 50-53% for clean and haemolysed sera. Hence, haemolysis did not reduce the mean observed serum antibody prevalence. However, 10 samples changed their classification after repeated freeze-thawing. This included 3 (15%) of the clean sera and 7 (41%) of the haemolysed sera.
We recommend (1) establishing more restrictive cut-off values when testing wildlife sera, (2) recording serum quality prior to sample banking, (3) recording the number of freezing-thawing cycles and (4) store sera in various aliquots to reduce repeated usage. For instance, sera with more than 3 freeze-thaw cycles and a haemolysis of over 3 on a scale of 4 should better be discarded for serum antibody monitoring. Even clean (almost not haemolysed) sera should not go through more than 5 freeze-thaw cycles.
监测野生动物疾病对于识别疾病发生情况的变化很有必要。野生动物血液样本对此目的很有价值，但采集时常常出现溶血现象。为了最大化信息，血清通常要经过反复分析和冻融循环。在此，我们使用了保存在-20°C且解冻多达五次的清洁和溶血的欧亚野猪血清样本，来研究这两种处理对用于检测抗猪疱疹病毒1（ADV）抗体的商业ELISA检测结果的影响。
清洁血清和溶血血清中抗ADV抗体的估计流行率为50-53%。因此，溶血并没有降低观察到的血清抗体平均流行率。然而，10个样本在反复冻融后改变了分类。这包括3个（15%）清洁血清样本和7个（41%）溶血血清样本。
我们建议：（1）在检测野生动物血清时设定更严格的临界值；（2）在样本储存前记录血清质量；（3）记录冻融循环次数；（4）将血清分装储存以减少重复使用。例如，对于血清抗体监测，冻融循环次数超过3次且溶血程度在4级中超过3级的血清最好丢弃。即使是清洁（几乎未溶血）血清，冻融循环次数也不应超过5次。
