The viral genome is a linear double-stranded DNA molecule with inverted terminal repeat sequences bound by terminal proteins, and contains a gene encoding a putative type B DNA polymerase (Bath et al., 2006, Dyall-Smith et al., 2021) (see Figure 1.Pleolipovirdae).
The virion of His2 contains three major structural protein types: internal membrane protein VP27, and two spike proteins, VP28 and VP29. An additional structural protein, VP32, with an unknown function, has been identified and shares no homologues with the members of the other genera (Pietilä et al., 2012, Senčilo et al., 2012). The spike protein VP28 of His2 contains a lipid modification (Pietilä et al., 2012). The His2 internal membrane protein VP27, encoded within the conserved ORF cluster, is not a homologue of internal membrane proteins of other pleolipoviruses, based on amino acid sequence similarity. However, it has an analogous function in the virion, i.e. it can be considered a functional homologue (Pietilä et al., 2012).
Species demarcation criteria
Viruses with genomes that differ by more than 5% are assigned to different species.
See also the genus demarcation criteria at the family level