Amphibian ranaviruses in Europe: important directions for future research

Lewis J Campbell,Xavier A Harrison,Alice H Pawlik,David Lesbarrères

doi:10.1139/facets-2020-0007

Lewis J Campbell, Xavier A Harrison + Show 2 more

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https://doi.org/10.1139/facets-2020-0007

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Abstract

Ranaviruses are an emerging group of pathogens capable of infecting all cold-blooded vertebrates. In Europe, ranaviruses pose a particularly potent threat to wild amphibian populations. Since the 1980s research on amphibian-infecting ranaviruses in Europe has been growing. The wide distribution of amphibian populations in Europe, the ease with which many are monitored, and the tractable nature of counterpart ex situ experimental systems have provided researchers with a unique opportunity to study many aspects of host–ranavirus interactions in the wild. These characteristics of European amphibian populations will also enable researchers to lead the way as the field of host–ranavirus interactions progresses. In this review, we provide a summary of the current key knowledge regarding amphibian infecting ranaviruses throughout Europe. We then outline important areas of further research and suggest practical ways each could be pursued. We address the study of potential interactions between the amphibian microbiome and ranaviruses, how pollution may exacerbate ranaviral disease either as direct stressors of amphibians or indirect modification of the amphibian microbiome. Finally, we discuss the need for continued surveillance of ranaviral emergence in the face of climate change.

Highlights

In 1979 a Scandinavian population of captive Atlantic cod (Gadhus morhua) began to exhibit elevated levels of morbidity and mortality
Developing our understanding of how the amphibian skin microbiome, environmental contaminants, and ranavirosis are inter-linked is important for amphibian conservation efforts and for potential mitigation strategies, such as probiotic treatments; to work in wild systems we must have as full an appreciation as possible about how they will influence and be influenced by the complex interactions between host, pathogen, and environment
It is imperative that we continue to monitor the spread of ranaviruses throughout Europe and to assess which currently naïve European amphibian species are likely to be most vulnerable to infection, allowing for the targeting of conservation efforts in regions where the impact of ranaviral emergence is likely to be severe

Summary

Introduction

In 1979 a Scandinavian population of captive Atlantic cod (Gadhus morhua) began to exhibit elevated levels of morbidity and mortality. With the help of these “citizen scientists” researchers in the United Kingdom have been able to establish a network of R. temporaria populations of known disease history, allowing for several comparative and (or) longitudinal studies that have advanced our understanding of interactions between ranaviruses and their hosts at the individual and the population level (Lawson et al 2015).

Results

Conclusion