Department of Biological Sciences, George Washington University, Washington, DC, United States.
Front Immunol. 2021 Aug 20;12:737403. doi: 10.3389/fimmu.2021.737403. eCollection 2021.
The global amphibian declines are compounded by ranavirus infections such as Frog Virus 3 (FV3), and amphibian tadpoles more frequently succumb to these pathogens than adult animals. Amphibian gastrointestinal tracts represent a major route of ranavirus entry, and viral pathogenesis often leads to hemorrhaging and necrosis within this tissue. Alas, the differences between tadpole and adult amphibian immune responses to intestinal ranavirus infections remain poorly defined. As interferon (IFN) cytokine responses represent a cornerstone of vertebrate antiviral immunity, it is pertinent that the tadpoles and adults of the anuran frog mount disparate IFN responses to FV3 infections. Presently, we compared the tadpole and adult responses to intestinal FV3 infections. Our results indicate that FV3-challenged tadpoles mount more robust intestinal type I and III IFN responses than adult frogs. These tadpole antiviral responses appear to be mediated by myeloid cells, which are recruited into tadpole intestines in response to FV3 infections. Conversely, myeloid cells bearing similar cytology already reside within the intestines of healthy (uninfected) adult frogs, possibly accounting for some of the anti-FV3 resistance of these animals. Further insight into the differences between tadpole and adult frog responses to ranaviral infections is critical to understanding the facets of susceptibility and resistance to these pathogens.
全球两栖动物数量的减少与蛙病毒 3（FV3）等 Ranavirus 感染有关，而两栖动物的蝌蚪比成年动物更容易受到这些病原体的影响。两栖动物的胃肠道是 Ranavirus 进入的主要途径，病毒的发病机制常常导致该组织内出血和坏死。然而，蝌蚪和成年两栖动物对肠道 Ranavirus 感染的免疫反应之间的差异仍未得到明确界定。由于干扰素 (IFN) 细胞因子反应是脊椎动物抗病毒免疫的基石，因此有必要研究无尾目蛙类的蝌蚪和成年个体对 FV3 感染的 IFN 反应存在差异。目前，我们比较了蝌蚪和成年个体对肠道 FV3 感染的反应。研究结果表明，FV3 感染的蝌蚪比成年青蛙在肠道中产生更强的 I 型和 III 型 IFN 反应。这些蝌蚪的抗病毒反应似乎是由髓样细胞介导的，这些细胞在受到 FV3 感染时会被招募到蝌蚪的肠道中。相反，具有相似细胞学特征的髓样细胞已经存在于健康（未感染）成年青蛙的肠道中，这可能是这些动物对 FV3 具有一定抵抗力的原因之一。进一步了解蝌蚪和成年青蛙对 Ranavirus 感染的反应之间的差异，对于理解这些病原体的易感性和抗性方面至关重要。
