Evolutionary dynamics and genetic diversity from three genes of Anguillid Rhabdovirus

Wild freshwater eel populations have dramatically declined in recent last decades in Europe and America, partially through the impact of several factors including the widespread of infectious diseases. The Anguillid rhabdoviruses Eel Virus European X (EVEX) and Eel Virus American (EVA) play potentially a role in this decline, even if their real contribution is still unclear. In this study, we investigate the evolutionary dynamics and genetic diversity of Anguillid rhabdoviruses by analyzing sequences from the glycoprotein (G), nucleoprotein (N), and phosphoprotein (P) genes of 57 viral strains collected from 7 countries over 40 years using Maximum likelihood and Bayesian approaches. Phylogenetic trees from the three genes are congruent and allow to clearly distinguish two monophyletic groups, European and American. Results of nucleotide substitution rates per site per year indicate that the P gene is subjected to evolve more rapidly. The nucleotide diversity observed is low (2-3 %) for the three genes, with a significantly higher variability within the P gene which encodes multiple proteins from a single genomic RNA sequence, particularly a small C protein. This putative C protein could be a potential molecular marker suitable for characterization of distinct genotypes within Anguillid rhabdoviruses. This study provides to our knowledge the first molecular characterization of EVA, brings new insights on the evolutionary dynamics of two genotypes of Anguillid rhabdovirus, and is a baseline for further investigations on the tracking of its spread.