Tan Jianming, Cooke Julie, Clarke Nadeene, Tannock Gregory A
Department of Biotechnology and Environmental Biology, School of Applied Sciences, RMIT University, Bundoora Victoria, Australia.
Avian Pathol. 2007 Oct;36(5):351-9. doi: 10.1080/03079450701557149.
A real-time quantitative polymerase chain reaction was utilized to study the in vivo replication of Marek's disease vaccine viruses and of virulent oncogenic strains. In the first of four experiments, the growth of the herpes virus of turkeys (HVT) vaccine was detectable in various organs of infected chicken embryos, with the highest viral loads being present in the spleen. No evidence was obtained for replication of serotype-1 Marek's disease viruses in embryos. In the second experiment, viral loads were measured in several organs of chickens after administration of the Rispens and HVT vaccines immediately after hatching. Lowest levels were noted for the Rispens strain after 1 to 8 weeks. By contrast, HVT vaccine grew well in all tested organs, with the highest loads being present in the spleen. Highest loads were observed in unvaccinated birds after challenge with the highly virulent strain MPF57 at day 8, especially in lymphoid organs. A positive relationship was observed between viral load and clinical signs, including tumour formation. In a third study, viral loads were measured in the organs of chickens administered the Rispens vaccine on the day of hatch and challenged at day 8 with MPF57. High levels of clinical protection were afforded against MPF57 by the Rispens vaccine but, in confirmation of earlier findings, sterilizing immunity was not induced. In a fourth study, two experiments were conducted--in which viral loads were measured after challenge of chickens vaccinated with HVT in ovo or at day 1 after hatching. Similar protection was achieved in birds vaccinated in ovo on embryonic days 11 and 17, although protection was slightly, but not significantly, lower than for birds vaccinated at day 1.
采用实时定量聚合酶链反应研究马立克氏病疫苗病毒和强致癌毒株在体内的复制情况。在四项实验的第一项中，可在感染鸡胚的各个器官中检测到火鸡疱疹病毒（HVT）疫苗的生长，脾脏中的病毒载量最高。未获得1型马立克氏病病毒在胚胎中复制的证据。在第二项实验中，刚孵化后立即接种里森斯疫苗和HVT疫苗后，测量了鸡的几个器官中的病毒载量。1至8周后，里森斯毒株的水平最低。相比之下，HVT疫苗在所有测试器官中生长良好，脾脏中的载量最高。在第8天用高毒力毒株MPF57攻击后，未接种疫苗的鸡中观察到最高载量，尤其是在淋巴器官中。观察到病毒载量与包括肿瘤形成在内的临床症状之间存在正相关。在第三项研究中，测量了孵化当天接种里森斯疫苗并在第8天用MPF57攻击的鸡的器官中的病毒载量。里森斯疫苗对MPF57提供了高水平的临床保护，但正如早期研究结果所证实的那样，未诱导出无菌免疫。在第四项研究中，进行了两项实验——在实验中，测量了在胚胎期或孵化后第1天接种HVT疫苗的鸡受到攻击后的病毒载量。在胚胎第11天和第17天在胚胎期接种疫苗的鸡中获得了类似的保护，尽管保护水平略低于但不显著低于在第1天接种疫苗的鸡。
