Members of the subfamily Betairidovirinae possess larger virions than vertebrate iridoviruses and display fiber-like extensions of variable length. They also possess larger genomes than members of the Alphairidovirinae, display a lower G+C content, lack extensive cytosine DNA methylation, and infect mainly invertebrate hosts. Although they infect a wide range of agricultural pests and medically-important insects such as mosquitoes, their study has been relatively neglected and important information regarding host range, number of viral species, and replication strategy is incomplete (Williams and Ward 2010, Williams et al., 2016).
Genus demarcation criteria
Historically genera within this subfamily were distinguished by virion size and the iridescent hue seen in infected insects and purified virus stocks. Given increasing numbers of fully sequenced viral genomes within this subfamily, membership within, and composition of, the subfamily has markedly changed in recent years and is currently based on phylogenetic analysis of complete viral genomes (Figure 6.Iridoviridae).