Subfamily: Twortvirinae

Genus: Kayvirus


Distinguishing features

Genomes of known members fall in the range of 125–153 kbp (Philipson et al., 2018, Oliveira et al., 2019) and GenBank accession MT554104. Staphylococcus phage K has a genome of 148.4 kbp (including 8.5 kbp terminal repeats) encoding 212 proteins, 4 tRNAs and 9 other non-coding RNAs ( Finstrlová et al., 2022). Genes for 21 proteins are within the terminal repeats and thus are duplicated in the virion DNA (Gill 2014). Infection is followed by the degradation of host DNA and the degradation products are used as building blocks for the synthesis of phage DNA (Rees and Fry 1981). Members of the genus infect Staphylococcus sp. Most of them have been isolated as infecting S. aureus, but at least some can also infect representatives of other Staphylococcus species.

Species demarcation criteria

Members of the same species are more than 95% identical in genome nucleotide sequence, including the terminal repeat region. Phages with genomes that differ by more than 5% are assigned to different species.