Abstract
Ranaviruses can infect both captive and wild cold-blooded vertebrates,
leading to significant economic and environmental losses. With the cases
of ranavirus infection increasing, many ranavirus genomic sequences were
published, but little is known about ranavirus taxonomy on a whole
genome level. In this study, 44 ranaviruses core genes were identified
in 32 ranaviruses genome suquences by using PanX. The Neighbor joining
phylogenetic trees (NJ-tree) based on 44 ranaviruses core genes and 24
iridoviridae core genes and composition vector phylogenetic tree
(CV-Tree) based on whole genome were constructed. The three of
phylogenetic trees showed that 32 ranavirus isolates can be divided to 4
different subspecies including GIV-like, EHNV-like, FV3-like and
CMTV-like, and subspecies taxonomic position of three phylogenetic trees
were consistent. However, the phylogenetic position of ToRV could not be
determined if it belongs to FV3-like or CMTV-like group. Subsequently,
we carried out dot plot analysis and confirmed that ToRV should belong
to CMTV-like group. Based on dot plot analysis and phylogenetic trees,
taxonomic classification of ranaviruses were confirmed. Finally, 4 genes
which are suitable for the construction of phylogenetic tree were
selected from ranavirus core genes by recombination analysis,
substitution saturation analysis and single-gene phylogenetic analysis.
Phylogenetic tree based on concatenated sequences of the 4 selected
genes showed that classification of subspecies was identical with 3 of
the phylogenetic trees. Conclusion: our results confirmed taxonomic
identification of ranaviruses, the 4 selected genes used in phylogenic
analysis will make taxonomic identification more convenient and
accurate.