Family: Chaseviridae

Subfamily: Nefertitivirinae

Distinguishing features

Members of this subfamily infect a range of bacteria in the Enterobacteriales, including Proteus mirabilis (Proteus phage Myduc, (Tran et al., 2019)), Erwinia amylovora and Pantoea agglomerans (Erwinia phage Faunus; Erwinia phage vB_EamM-Y2 (Born et al., 2011); Pantoea phage vB_PagM_SSEM1), Escherichia coli (Escherichia phage vB_EcoM-4HA13, Escherichia phage flopper, Escherichia phage ST32, Escherichia phage Mangalista (Atkison et al., 2019), Escherichia phage phiEcoM-GJ1 (Jamalludeen et al., 2008)) and, Pectobacterium carotovorum subsp. carotovorum (Pectobacterium PM1(Lim et al., 2014); Pectobacterium phage PP101). On average, the virus genomes are 53.45 kbp (43.8 %G+C) and encode 0–1 tRNAs and 78 proteins.  In four cases, the genomes have been found to possess long terminal repeats. 

At the protein level, CoreGenes 5.0 analysis (https://coregenes.ngrok.io/), which employs a bidirectional best hit approach, identifies 37 conserved proteins, representing 47.4% of the viral proteome. These included: RNA polymerase, single-stranded DNA-binding protein, DNA primase/helicase, DNA polymerase, 5′-3′ exonuclease, endonuclease, DNA ligase, deoxynucleoside monophosphate kinase, terminase large subunit, portal protein, major capsid protein, head-tail adaptor protein, tail completion protein, tail sheath protein, tail tube protein, tail tube initiator protein, several baseplate proteins, holin and SAR endolysin. 

Genus demarcation criteria

Genera in the family Chaseviridae are well-supported monophyletic clades by VIRIDIC clustering and in (concatenated) marker gene phylogenies. Members of a genus share at least 70% nucleotide identity across the genome. Members of the same genus generally infect members of the same bacterial genus.