US-UK Collab: The consequences of transmissible vaccines on disease ecology and pathogen evolution: Marek's disease virus as a case study

人类和兽医数十年的证据无疑证明了疫苗接种在控制传染病方面的重要作用。可传播疫苗，或自我传播疫苗，是能够在个人之间传播的疫苗。这种疫苗的本质是能够向本身没有直接接种疫苗的宿主传播，在野生动物种群干预方面显示出很大的希望，因为每种接种的疫苗都有可能接触到原本无法接触到的潜在宿主。它们对养鱼或养鸡等养殖种群也可能有用，因为在这些种群中，为每种动物接种疫苗都将是困难的。此外，这种疫苗可能会随着时间的推移在动物种群中持续存在，降低每次种群变化时接种疫苗的紧迫性，例如在繁殖季节或农场队列之间。然而，这种可传播疫苗对病原体的病毒动力学和进化以及潜在的重组的影响尚未得到检验。这个项目是根据上一次EEID拨款的结果开发的，当时我们发现，更有效的预防马立克氏病的Rispens疫苗可以在禽类之间传播。因此，这项调查的概念是更多地研究在禽类之间传播的可传播疫苗的传播动态和保护。作为该项目的一部分，我们将调查可传播疫苗是否也可以推动病毒进化到更强的毒力，以及这种疫苗是否可以促进重组。我们将试图通过在鸡身上进行对照实验来回答关键问题，即可传播的疫苗是会让事情变得更好还是更糟。到目前为止，一些关于可传播疫苗的理论研究还没有给出确凿的答案。我们相信，马立克氏病有效的可传播疫苗模型将对检验如何将理论和经验数据结合起来询问可传播疫苗对疾病生态和进化的总体后果具有重要意义。

Decades of evidence from Human and Veterinary Medicine has undoubtedly demonstrated the important role of vaccination in the control of infectious diseases. Transmissible vaccines, or self-disseminating vaccines, are vaccines capable of transmitting between individuals. Such vaccines, by nature of their ability to disseminate to hosts that were themselves not directly vaccinated, show substantial promise for interventions in wildlife populations, because each administered vaccine has the potential to reach otherwise inaccessible potential hosts. They may also be useful on farmed populations such as fish or chickens where vaccinating every animal will be difficult. Moreover, such vaccines might be capable of persisting in the animal population over time, reducing the urgency to vaccinate every time populations turn over, such as during reproductive seasons or between farm cohorts. However, the effects of such transmissible vaccines on the virus dynamics and evolution of pathogens, as well as potential recombination have not been examined. This project is developed from the findings of the previous EEID grant, where we found that the more efficient Rispens vaccine against Marek's disease is transmissible between birds. So the concept of the investigation is to examine more about the transmission dynamics and protection of transmissible vaccines that spread between birds. As part of the project, we will investigate whether transmissible vaccine can also drive virus evolution to greater virulence and whether such vaccines can contribute to recombination. The key question we will try to answer using controlled experiments in chickens as to whether transmissible vaccines will make things better or worse. So far a number of theoretical studies on transmissible vaccines have not given conclusive answers. We believe that the efficient transmissible vaccine model in Marek's disease will be valuable to examine how the theory and empirical data can be combined to ask what the overall consequences of transmissible vaccines are on disease ecology and evolution.