Human Adenovirus 7 belongs to species B of the genus *Mastadenovirus*. It is a non‑enveloped virus with a linear double‑stranded DNA genome and an icosahedral capsid, known for causing outbreaks of severe respiratory illness and pneumonia.
Virology and Pathogenesis
Adenovirus 7 particles contain a protein capsid composed of hexon and penton base proteins with fiber projections that mediate attachment to host cell receptors such as desmoglein 2. Following receptor‑mediated endocytosis, the capsid uncoats and the viral DNA enters the nucleus. Early gene products manipulate host cell functions and promote viral DNA replication using a virus‑encoded DNA polymerase, while late gene products form structural components for assembly of progeny virions. The virus shows a tropism for respiratory epithelial cells and can induce a robust inflammatory response that contributes to tissue damage.
Clinical Manifestations and Outbreaks
Type 7 adenoviruses are associated with acute respiratory disease that can progress to severe pneumonia, particularly in young children, immunocompromised individuals and crowded settings. Symptoms include high fever, cough, dyspnea and, occasionally, conjunctivitis. Epidemic outbreaks of adenovirus 7 have been documented in military camps, long‑term care facilities and pediatric wards, sometimes resulting in significant morbidity and mortality. Transmission occurs through respiratory droplets and fomites. Diagnosis is confirmed by PCR or viral culture, and supportive care is the mainstay of treatment; antiviral drugs such as cidofovir may be considered for severe infections. A live oral vaccine against adenovirus 7 and type 4 is administered to U.S. military recruits to mitigate outbreaks. Human adenovirus 7 highlights the capacity of adenoviruses to cause severe respiratory disease and underscores the importance of surveillance and preventive measures in high‑risk environments. Related Terms: human adenovirus 4, human adenovirus 14, pneumonia, adenovirus vaccine, acute respiratory disease