CAREER: The roles of amphibian macrophages in susceptibility and immunological resistance to the Frog Virus 3 ranavirus

全球青蛙数量正在下降，近三分之二的青蛙物种面临灭绝的威胁。病毒感染，如青蛙病毒3号，是造成这些下降的重要原因。蝌蚪比成年青蛙更容易感染病毒。有必要更好地了解决定青蛙病毒3的易感性和抗性的免疫机制。这些知识可以用来防止青蛙数量的进一步下降。在这方面，值得注意的是，被称为“巨噬细胞”的免疫细胞对于病毒感染青蛙和青蛙对感染的免疫反应都很重要。这个奖项将定义在蝌蚪和成年青蛙中发现的巨噬细胞的不同种群是如何作为这种病毒的免疫屏障，还是作为青蛙病毒3型进入、传播到身体其他部位、持续存在并传播到其他青蛙的门户。这项工作将扩大对包括人类在内的脊椎动物如何抵抗病毒感染的理解，并可能导致针对人类病毒性疾病的新疗法。此外，它将增加当地社区对保护问题的认识，并在各级教育中为学生，包括代表性不足的少数民族提供教育机会。迄今为止研究的几乎所有脊椎动物巨噬细胞的分化都依赖于巨噬细胞集落刺激因子（M-CSF）受体。它被M-CSF配体和白细胞介素34 （IL-34）细胞因子激活。在非洲爪蟾中，M-CSF衍生的巨噬细胞加重蝌蚪和成年蛙的青蛙病毒3感染，而IL-34衍生的巨噬细胞赋予抗病毒抗性。在非洲爪蟾中，与其他脊椎动物一样，il -34刺激的巨噬细胞的主要抗病毒效应物似乎是干扰素。有趣的是，两栖动物拥有更多的干扰素。这些干扰素的不同亚群在蝌蚪和成年青蛙中受到刺激，以响应青蛙病毒3型感染，这表明不同亚群的巨噬细胞对青蛙病毒3型的反应不同。该奖项将(1)阐明m - csf刺激和il -34刺激的巨噬细胞在青蛙病毒3型的易感性和抗性中所起的作用，(2)表征两种巨噬细胞群体产生的不同干扰素亚群的抗青蛙病毒3型能力。这项工作可以通过增强青蛙对病毒感染的抵抗力或使用干扰素治疗来防止青蛙病毒3的复制，从而促进对抗两栖动物数量下降的措施的发展。此外，由于两栖动物和哺乳动物的免疫系统之间有许多相似之处，这项研究可以加深对人类免疫系统如何进化的理解，并为治疗人类病毒感染提供新的方法。该奖项旨在支持旨在提高公众对两栖动物保护意识的宣传活动。它为当地的高中和本科生（包括少数族裔）以及研究生和博士后导师提供动手实验室经验。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Frog populations around the globe are declining with almost two-thirds of all frog species threatened with extinction. Viral infections, such as Frog Virus 3, are significant contributors to these declines. Tadpoles are far more susceptible to viruses than adult frogs. There is a need to better understand the immune mechanisms that dictate susceptibility and resistance to Frog Virus 3. Such knowledge could be used to prevent further decline in frog populations. In this respect, it is notable that immune cells known as 'macrophages' are important both for the virus to infect the frog and for the frog's immune response against the infection. This award will define how distinct populations of macrophages found in the tadpole and adult frog serve either as immune barriers to this virus or as gateways for Frog Virus 3 entry, dissemination to other parts of the body, persistence and spread to other frogs. This work will broaden understanding of how vertebrates, including humans, resist viral infections and potentially lead to new therapies against viral diseases in humans. In addition, it will increase knowledge of conservation issues in the local community and provide educational opportunities to students, including underrepresented minorities, at all educational levels.The differentiation of nearly all vertebrate macrophages studied to date depends on the macrophage colony-stimulating factor (M-CSF) receptor. It is activated by both the M-CSF ligand and the interleukin34 (IL-34) cytokine. In Xenopus laevis, macrophages derived by M-CSF exacerbate Frog Virus 3 infections in the tadpole and adult frog whereas macrophages derived by IL-34 confer anti-viral resistance. In, Xenopus laevis, as in other vertebrates, the major antiviral effectors of IL-34-stimulated macrophages appear to be interferons. Interestingly, amphibians possess an expanded repertoire of interferons. Different subsets of these interferons are stimulated in tadpoles and adult frogs, in response to Frog Virus 3 infection, suggesting that different subsets of macrophages respond differently to Frog Virus 3. This award will (1) elucidate the roles played by M-CSF-stimulated and IL-34-stimulated macrophages in susceptibility and resistance to Frog Virus 3, (2) characterize the anti-Frog Virus 3 capacities of the distinct interferon subsets produced by the two macrophage populations. This work could foster development of measures to counteract amphibian declines by enhancing frog resistance to viral infections or using interferon treatment to prevent Frog Virus 3 replication. Moreover, as there are many parallels between the amphibian and mammalian immune systems, this research could deepen the understanding of how the human immune system evolved and lead to new ways for treating human viral infections. This award supports outreach aimed at raising public awareness of amphibian conservation. It provides hands-on laboratory experience to local high school and undergraduates, including underrepresented minorities, and mentors graduate students and postdoctoral fellows.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.