Reid Scott M, Parida Satya, King Donald P, Hutchings Geoffrey H, Shaw Andrew E, Ferris Nigel P, Zhang Zhidong, Hillerton J Eric, Paton David J
Institute for Animal Health, Pirbright Laboratory, Ash Road, Pirbright, Woking, Surrey, GU24 0NF, United Kingdom.
Vet Res. 2006 Jan-Feb;37(1):121-32. doi: 10.1051/vetres:2005040.
Foot-and-mouth disease virus (FMDV) can be excreted in milk and thereby spread infection to susceptible animals in other holdings. The feasibility of using real-time reverse transcription polymerase chain reaction (rRT-PCR) as a diagnostic tool for detection of FMDV in milk was assessed by studying the excretion of virus from experimentally-infected cattle. Fore- and machine milk samples were collected over a 4-week period from two dairy cows infected with FMDV and from two in-contact cows held in the same pen. The whole, skim, cream and cellular debris components of the milks were tested by automated rRT-PCR and results compared to virus isolation (VI) in cell culture. The onset of clinical signs of FMD in all four cows correlated with viraemia, and the presence of FMDV in other clinical samples. rRT-PCR results matched closely with VI in detecting FMDV in all milk components and generally coincided with, but did not consistently precede, the onset of clinical signs. rRT-PCR detected FMDV in milk up to 23 days post inoculation which was longer than VI. Furthermore, the detection limit of FMDV in milk was greater by rRT-PCR than VI and, in contrast to VI, rRT-PCR detected virus genome following heat treatment that simulated pasteurisation. rRT-PCR was also able to detect FMDV in preservative-treated milk. In conclusion, this study showed that automated rRT-PCR is quicker and more sensitive than VI and can be used to detect FMDV in whole milk as well as milk fractions from infected animals.
口蹄疫病毒（FMDV）可随乳汁排出，从而将感染传播给其他养殖场中的易感动物。通过研究实验感染牛的病毒排泄情况，评估了使用实时逆转录聚合酶链反应（rRT-PCR）作为检测乳汁中FMDV的诊断工具的可行性。在4周时间内，从两头感染FMDV的奶牛以及同一围栏中与之接触的两头奶牛采集了前乳和机械挤奶样本。对乳汁的全脂、脱脂、奶油和细胞碎片成分进行了自动化rRT-PCR检测，并将结果与细胞培养中的病毒分离（VI）结果进行比较。所有四头奶牛的口蹄疫临床症状发作均与病毒血症以及其他临床样本中FMDV的存在相关。在检测所有乳汁成分中的FMDV时，rRT-PCR结果与VI结果密切匹配，并且通常与临床症状发作时间一致，但并非始终先于临床症状发作。rRT-PCR在接种后长达23天的乳汁中检测到了FMDV，这比VI检测的时间更长。此外，rRT-PCR对乳汁中FMDV的检测限高于VI，并且与VI不同的是，rRT-PCR在模拟巴氏杀菌的热处理后检测到了病毒基因组。rRT-PCR还能够检测经防腐剂处理的乳汁中的FMDV。总之，本研究表明，自动化rRT-PCR比VI更快、更灵敏，可用于检测感染动物全脂乳以及乳汁各部分中的FMDV。
