Wild-Type Human Adenovirus (Serotype 17)

Wild-type human adenovirus serotype 17 (HAdV-17) belongs to the Human mastadenovirus D group and is primarily transmitted through direct contact with infected individuals, respiratory droplets, or fomites. It can also be transmitted via the fecal-oral route, particularly in crowded or unsanitary environments. Upon entry into the body, the virus attacks epithelial cells of the respiratory tract, gastrointestinal tract, or conjunctiva, depending on the route of infection. The virus binds to host cell receptors (such as CD46 or desmoglein-2), promoting viral internalization and subsequent replication within the cell nucleus. Clinical manifestations vary, ranging from mild respiratory illness (such as pharyngitis and bronchitis) to severe disease (such as keratoconjunctivitis or gastroenteritis), particularly in immunocompromised individuals. HAdV-17 exhibits tropism for mucosal surfaces, leading to persistent or latent infection, which promotes viral shedding and community transmission.

HAdV-17 possesses a non-enveloped icosahedral capsid approximately 90 nanometers in diameter, composed of 252 capsomeres (240 hexons and 12 pentons). The bases of the pentons are connected to fibrillar projections, which mediate host cell attachment and entry. Its genome consists of a linear double-stranded DNA molecule (approximately 36 kb) encoding the early (E1-E4), intermediate, and late (L1-L5) genes responsible for replication, immune evasion, and capsid assembly. Notably, the E3 region contains immunomodulatory proteins that counteract host defenses, while the E1A/E1B genes regulate cell cycle progression. The genome is flanked by inverted terminal repeats (ITRs), which are essential for replication and packaging.