Phylogenetic Relationships and Evolution of the Genus Eganvirus (186-Type) Yersinia Pestis Bacteriophages

Plague is an endemic infectious disease caused by Yersinia pestis. In this study, we isolated fourteen phages with similar sequence arrangements to phage 186; these phages exhibited different lytic abilities in Enterobacteriaceae strains. To illustrate the phylogenetic relationships and evolutionary relationships between previously designated 186-type phages, we analysed the complete sequences and important genes of the phages, including whole-genome average nucleotide identity (ANI) and collinearity comparison, evolutionary analysis of four conserved structural genes (V, T, R, and Q genes), and analysis of the regulatory genes (cI, apl, and cII) and integrase gene (int). Phylogenetic analysis revealed that thirteen of the newly isolated phages belong to the genus Eganvirus and one belongs to the genus Felsduovirus in the family Peduoviridae, and these Eganvirus phages can be roughly clustered into three subgroups. The topological relationships exhibited by the whole-genome and structural genes seemed similar and stable, while the regulatory genes presented different topological relationships with the structural genes, and these results indicated that there was some homologous recombination in the regulatory genes. These newly isolated 186-type phages were mostly isolated from dogs, suggesting that the resistance of Canidae to Y. pestis infection may be related to the wide distribution of phages with lytic capability.