ICTV Virus Taxonomy Profile: Adenoviridae 2022

1Adenovirus virions are non-enveloped, pseudo T=25 icosahedral particles. The capsid consists of 240 non-vertex (hexon) and 12 vertex capsomers (penton). The latter consist of the penton base and a protruding fiber protein trimer (Table 1, Fig. 1). The minor, cementing proteins show genus-specific variation but LH3 (atadenoviruses) and protein IX (mastadenoviruses) share a capsid-binding motif.

2The genome is a single linear molecule of dsDNA of 24 630–48 395 bp with inverted terminal repeats of 26–721 bp (Fig. 2). A virus-encoded terminal protein is covalently linked to the 5′-end of each DNA strand.

3Entry of virus into cells occurs by attachment of the fiber trimer knob to cellular receptors followed by internalization involving interaction between the penton base and cellular αv integrins. After uncoating, the virus core is delivered to the nucleus, the site of virus RNA transcription, DNA replication and assembly. Infection results in the arrest of synthesis of host DNA, mRNA and proteins. Transcription by host RNA polymerase II involves both DNA strands of the virus genome. Primary transcripts are capped and polyadenylated. Complex splicing patterns govern the production of mRNA families. In primate adenoviruses, virus-associated RNA genes transcribed by cellular RNA polymerase III facilitate translation of late virus mRNAs and block the cellular interferon response.

4Human infections are usually subclinical but can, especially in immunosuppressed patients, induce acute respiratory symptoms, adenoidal–pharyngeal conjunctivitis, epidemic keratoconjunctivitis, hepatitis, acute gastroenteritis (infantile virus-caused diarrhoea), persistent interstitial infection in the kidney and haemorrhagic cystitis. Mastadenovirus infections in animals are common, but disease usually appears only when predisposing factors are present. Canine adenovirus 1 is the causative agent of infectious canine hepatitis (a life-threatening disease of puppies). Skunk adenovirus 1 also infects African pigmy hedgehog, porcupine, racoon and a New World monkey. Both viruses share ancestry with bat adenoviruses. In chickens, hepatitis-hydropericardium syndrome is associated with fowl adenovirus 4 and gizzard erosion with fowl adenovirus 1. Additional aviadenoviruses cause inclusion body hepatitis. The atadenovirus duck adenovirus 1 is the causative agent of egg drop syndrome in chickens, and deer adenovirus 1 infection has resulted in the death of thousands of deer in California (USA). A siadenovirus causes turkey haemorrhagic enteritis.

5Current taxonomy: ictv.global/taxonomy. Genus and species demarcation is based mainly on phylogenetic criteria but also on genome organization and biological characteristics. Genus Mastadenovirus: >50 species (members infecting mammals); Aviadenovirus: >14 species (birds); Atadenovirus: >9 species (reptiles, birds, ruminants and marsupials); Siadenovirus: >7 species (birds, frogs and tortoises); Ichtadenovirus: 1 species (white sturgeon); Testadenovirus: 1 species (red-eared slider).

6Full ICTV Report on the family Adenoviridae: ictv.global/report/adenoviridae.

7Sequenced adenoviruses: sites.google.com/site/adenoseq.