Definition
Adenovirus is a medium‑sized non‑enveloped virus with an icosahedral capsid and a linear double‑stranded DNA genome. It belongs to the family Adenoviridae. Human adenoviruses include more than fifty serotypes that infect the respiratory tract, conjunctiva, gastrointestinal tract and urinary tract. The virus is stable in the environment and can withstand pH fluctuations and some disinfectants.
Explanation
The capsid is roughly ninety to one hundred nanometres in diameter and is built from hexon and penton base proteins with protruding fibre proteins. The fibre binds to cellular receptors such as the coxsackievirus and adenovirus receptor and integrins on epithelial cells. Once inside the cell the virus travels to the nucleus where early genes direct host shutoff and DNA replication. Late genes encode structural proteins and assembly occurs in the nucleus. New virions are released by lysis. Infections often cause mild upper respiratory symptoms, sore throat, fever and conjunctivitis. Some serotypes cause diarrhoea or cystitis. Severe disease can occur in infants, the elderly and people with weakened immune systems. Transmission occurs through respiratory droplets, contaminated surfaces, swimming pools and the faecal‑oral route. There is no widely available specific antiviral therapy.
Diseases and Uses
Types four and seven have caused outbreaks of acute respiratory disease in military recruits. Types eight, nineteen and thirty seven are associated with epidemic keratoconjunctivitis, and types forty and forty one cause childhood gastroenteritis. A live vaccine for types four and seven is given to some military populations. Researchers use recombinant adenoviruses as vectors for gene therapy and vaccination because they can deliver genes to many cell types and induce strong immune responses.
Adenoviruses are common pathogens that rarely cause severe disease in healthy people. Their unique stability and genetic simplicity make them important tools for research, vaccines and gene delivery.
Related Terms: Adenoviridae, Viral vector, Respiratory virus, DNA virus, Conjunctivitis