Adenoviridae

Adenoviridae is a family of non-enveloped, icosahedral viruses with linear double-stranded DNA genomes. Virions are typically 70–90 nm in diameter and display fiber projections at the vertices that mediate receptor binding. The genome is about 26–45 kilobases and is transcribed in a regulated fashion with early and late transcription units. Replication takes place in the nucleus of infected cells, and viral gene expression is tightly coordinated with DNA synthesis and virion assembly.

Taxonomy and hosts: The family comprises multiple genera, including Mastadenovirus, which infects mammals (including humans), and Aviadenovirus, Atadenovirus and others that infect birds and other vertebrates. In humans, more than 50 serotypes have been described and are grouped by clinical syndromes. Transmission is via respiratory droplets, fecal-oral spread, ocular inoculation, and contact with contaminated surfaces; outbreaks occur in households, schools, and military settings.

Clinical aspects: In otherwise healthy people, adenovirus infections are usually mild and self-limited, causing common colds, pharyngitis, conjunctivitis, or diarrhea. Immunocompromised patients, the elderly, newborns, and transplant recipients are at risk of severe pneumonia, hepatitis, or disseminated disease. Viral shedding can persist for weeks in stool or respiratory secretions. Diagnosis relies on PCR, antigen tests, or viral culture.

Treatment and prevention: There are no broadly effective antiviral agents for routine adenovirus infection; management is supportive. Vaccines exist for serotypes 4 and 7 used in military personnel in some countries. General prevention includes good hygiene and disinfection. In biotechnology, adenoviruses are widely used as replication-defective vectors for gene delivery and vaccine development because they can efficiently transduce a range of cell types and accommodate sizable DNA inserts.