Abstract：
Monitoring Marek\'s disease (MD) vaccination is routinely done by evaluating the load of MD vaccine in the feather pulp (FP) between 7 and 10 days of age. However, attempts in our laboratory to detect a novel CVI-LTR vaccine in the FP samples from commercial flocks failed. The objective of this study was to evaluate the most suitable tissue and age to monitor CVI-LTR vaccination. We used two different commercial CVI988 vaccines as controls. One hundred and sixty 1-day-old commercial brown layers were vaccinated with either CVI-LTR, CVI988-A, CVI988-B or remained unvaccinated. Samples of the spleen, thymus, and bursa were collected at 3, 4, 5, and 6 days of age and samples of FP were collected at 7 and 21 days for DNA isolation. Our results showed that CVI-LTR replicated earlier than CVI988 vaccines in the lymphoid organs but was not detected in the FP at either 7 or at 21 days of age. We also confirmed that either the spleen or thymus collected at 4-6 days was a suitable sample to monitor CVI-LTR vaccination in commercial flocks. Finally, we evaluated the load of oncogenic MDV DNA in five commercial flocks that were vaccinated with either CVI-LTR + rHVT or CVI988-A + rHVT. The load of oncogenic MDV DNA was evaluated at 21 days in the FP in 20 chickens per group. Our results demonstrated that CVI-LTR was more successful in reducing oncogenic MDV DNA at 21 days of age than the CVI988-A strain.RESEARCH HIGHLIGHTSCVI-LTR replicates in the thymus and spleen earlier than CVI988.CVI-LTR replicates in lymphoid organs but it cannot be detected in feather pulp.CVI-LTR reduced the load of oncogenic MDV DNA more efficiently than CVI988.
摘要：
监测马立克病（MD）疫苗接种通常是通过评估7-10天龄之间的羽毛浆（FP）中MD疫苗的负荷来完成的。然而,我们实验室在来自商业群的FP样品中检测新型CVI-LTR疫苗的尝试失败了。这项研究的目的是评估最合适的组织和年龄来监测CVI-LTR疫苗接种。我们使用两种不同的商业CVI988作为对照。一百六十个一天大的商业棕色层接种了CVI-LTR，CVI988-A,CVI988-B,或未接种疫苗。脾脏样本,胸腺,并且在3、4、5和6日龄收集法氏囊,并且在7和21天时收集FP的样品用于DNA分离。我们的结果表明，CVI-LTR在淋巴器官中的复制时间比CVI988疫苗早，但在7天或21天大的FP中未检测到。我们还证实,在4-6天收集的脾或胸腺是监测商业鸡群中CVI-LTR疫苗接种的合适样品。最后,我们评估了5个接受CVI-LTR+rHVT或CVI988-A+rHVT疫苗接种的商业群体中致癌MDVDNA的载量。在FP中21天时在每组20只鸡中评估致癌MDVDNA的负荷。我们的结果表明，与CVI988-A菌株相比，CVI-LTR在21日龄时更成功地减少了致癌MDVDNA。
