Accuracy is crucial for polymerase chain reaction (PCR) diagnostic laboratories. We noticed inconsistent PCR results or false negatives that sometimes occurred when changing commercial brand of Taq DNA polymerase enzyme. Here, we tested 6 primer sets specific for 3 important aquaculture viruses (scale drop disease virus (SDDV), tilapia lake virus (TiLV), and white spot syndrome virus (WSSV)) using 7 brands of Taq DNA polymerase enzymes (RBC Bioscience, Invitrogen, PCRBiosystems, Bio-Helix, biotechrabbit, GeneAll, and New England BioLabs) with their original reaction buffers. False negative detection and variation in sensitivity of 10–1000 times were observed. Interestingly, only enzymes from RBC Bioscience and Invitrogen could amplify SDDV 252 bp products, while 5 other brands failed to do so. The use of reaction buffer from RBC Bioscience with Taq polymerase enzymes from other brands resulted in improvement of detection sensitivity and avoided false negatives. Comparison of ingredients of the 7 reaction buffers indicated that bovine serum albumin (BSA) and ammonium sulfate were present in the RBC Bioscience buffer but absent or not specified in 6 other brands. Subsequently, we found that adding ammonium sulfate to the original buffers of the 4 selected brands improved detection efficiency for most test reactions, while adding BSA alone or BSA plus ammonium sulfate showed no or little improvement. When tested with serial dilutions of DNA extracted from 2 SDDV-infected fish, adding ammonium sulfate into the original buffer of biotechrabbit brand could improve detection sensitivity 100 times, equal to the result of RBC Bioscience kit. We thus recommend that PCR reaction buffer with ammonium sulfate (10 mM) added might improve detection sensitivity and avoid false negative results in PCR detection assays.

准确性对于聚合酶链反应（PCR）诊断实验室至关重要。我们注意到改变Taq DNA聚合酶的商业品牌时，PCR结果不一致或有时会出现假阴性。在这里，我们使用7种品牌的Taq DNA聚合酶（RBC Bioscience， Invitrogen，PCRBiosystems，Bio-Helix，biotechrabbit，GeneAll和New England BioLabs）及其原始反应缓冲液。观察到假阴性检测和灵敏度变化10-1000倍。有趣的是，只有RBC Bioscience和Invitrogen的酶才能扩增SDDV 252 bp产品，而其他5个品牌则无法扩增。将RBC Bioscience的反应缓冲液与其他品牌的Taq聚合酶一起使用可提高检测灵敏度并避免假阴性。对7种反应缓冲液成分的比较表明，RBC Bioscience缓冲液中存在牛血清白蛋白（BSA）和硫酸铵，但在其他6个品牌中未指定或未指定。随后，我们发现将硫酸铵添加到4个所选品牌的原始缓冲液中可提高大多数测试反应的检测效率，而单独添加BSA或添加BSA加硫酸铵则无改善或几乎没有改善。用从2只SDDV感染鱼中提取的DNA进行连续稀释测试时，在biotechrabbit品牌的原始缓冲液中添加硫酸铵可以将检测灵敏度提高100倍，这与RBC Bioscience试剂盒的结果相同。