Mastadenovirus

Mastadenovirus is a genus of non-enveloped, linear double-stranded DNA viruses within the family Adenoviridae. It comprises mammalian adenoviruses, including human adenoviruses and animal adenoviruses such as canine adenoviruses. Members of the genus are generally host-restricted, though cross-species transmission can occur under certain circumstances.

Virions are icosahedral, about 70–90 nm in diameter, with a capsid formed by hexon and penton base proteins and fiber projections. The genome is a linear double-stranded DNA molecule of roughly 26–45 kilobases. Replication occurs in the host cell nucleus; early genes (including E1, E3, E4) regulate viral replication and host responses, while late genes encode the major structural proteins, such as hexon, penton base, and fiber.

Mastadenoviruses infect a wide range of mammals. In humans, infections are typically mild and involve the respiratory tract, eyes, or gastrointestinal tract; severe disease can occur in immunocompromised individuals. In animals, canine adenoviruses can cause infectious canine hepatitis (CAV-1) and respiratory disease (CAV-2). Transmission is usually via respiratory droplets, fecal-oral spread, direct contact, or contaminated surfaces; the non-enveloped virion is environmentally persistent.

Diagnosis is based on PCR or antigen testing from clinical specimens, virus isolation, or serology. Most infections are self-limited and require no specific antiviral therapy; management is supportive. Prevention in humans is limited to vaccines for certain serotypes used in military settings (e.g., serotypes 4 and 7) and good hygiene; canine vaccines based on CAV-2 provide cross-protection against CAV-1 in dogs.

Adenoviral vectors derived from Mastadenovirus, particularly human serotype 5, are widely used in gene therapy and vaccine development. These replication-defective vectors serve as platforms for delivering therapeutic genes, while ongoing research addresses safety, pre-existing immunity, and targeted delivery.