US22 proteins have been found across many animal DNA viruses and some vertebrates [3]. The name sake of this family US22 Swiss:P09722 is an early nuclear protein that is secreted from cells [2]. The US22 family may have a role in virus replication and pathogenesis [1]. Domain analysis showed that US22 proteins usually contain two copies of conserved modules which is homologous to several other families like SMI1 and SYD (commonly called SUKH superfamily) [3]. Bacterial operon analysis revealed that all bacterial SUKH members function as immunity proteins against various toxins. Thus US22 family is predicted to counter diverse anti-viral responses by interacting with specific host proteins [3].

1: Transcriptional analysis of the murine cytomegalovirus HindIII-I region: identification of a novel immediate-early gene region. Hanson LK, Dalton BL, Karabekian Z, Farrell HE, Rawlinson WD, Stenberg RM, Campbell AE; Virology 1999;260:156-164. PMID:10405367

2: Identification of homologues to the human cytomegalovirus US22 gene family in human herpesvirus 6. Efstathiou S, Lawrence GL, Brown CM, Barrell BG; J Gen Virol 1992;73:1661-1671. PMID:1321206

3: A novel immunity system for bacterial nucleic acid degrading toxins and its recruitment in various eukaryotic and DNA viral systems. Zhang D, Iyer LM, Aravind L; Nucleic Acids Res. 2011;39:4532-4552. PMID:21306995