Human Adenovirus 2 is a member of species C within the genus *Mastadenovirus*. It is a non‑enveloped icosahedral virus with a linear double‑stranded DNA genome that causes respiratory tract infections and has been widely used as a backbone for recombinant adenoviral vectors.
Morphology and Replication
Adenovirus 2 virions are built from hexon proteins forming the facets of the capsid and penton bases at each vertex bearing fiber proteins. The fiber knob binds to the coxsackievirus‑adenovirus receptor (CAR) on epithelial cells, while the penton base engages integrins to induce endocytosis. After escaping the endosome, the viral core docks at the nuclear pore and delivers its genome into the nucleus. Early proteins modulate host cell function and stimulate viral DNA replication using a terminal protein primer. Late genes encode structural components that assemble with replicated genomes to form new particles. Cell lysis releases virions, which are environmentally stable and can persist on surfaces, facilitating transmission via aerosols, contaminated water and fomites.
Clinical Relevance and Uses
Infections with adenovirus 2 most often present as self‑limited upper respiratory illness in children, manifesting with fever, cough, sore throat and rhinorrhea. Conjunctivitis and otitis media can also occur. In immunocompetent hosts, disease severity is generally mild, but immunocompromised patients may develop severe pneumonia or disseminated infection. Species C adenoviruses establish persistent infection in tonsils and adenoids. Human adenovirus 2, together with adenovirus 5, has served as a template for the development of replication‑defective vectors for gene therapy and vaccine delivery due to its ability to infect dividing and non‑dividing cells and elicit strong immune responses. Laboratory diagnosis relies on PCR or culture, and management is supportive; cidofovir may be considered for severe disease. Human adenovirus 2 exemplifies the common respiratory adenoviruses that circulate worldwide. Although usually benign, it has provided valuable tools for biotechnology and gene delivery. Related Terms: adenovirus, species C, respiratory infection, CAR receptor, adenoviral vector