Adenovirus Structure and Infection Process

Study Notes

Adenoviruses replicate in the nucleus, forming paracrystalline arrays of particles measuring 70-90 nm.
Adenovirus virions are non-enveloped with an icosahedral capsid containing double-stranded linear DNA.
Capsid comprises 240 hexon capsomeres (12 per triangular facet) and 12 pentameric penton capsomeres at vertices.
Fiber proteins extend from pentons, interacting with host-cell receptors like CAR (coxsackie B and adenovirus receptor), facilitating infection.

104 different human adenovirus (HAdV) types classified into seven species (A-G) based on genomic characteristics.
Species B, C, and E commonly detected in children with adenotonsillar hyperplasia, affecting 85% of cases.
Vaccine safety largely high, with few adverse effects; however, there can be moderate to severe respiratory symptoms.

HAdVs induce strong immune responses, including CD4+ and CD8+ T cell-mediated responses.
Some adenovirus types (e.g., Ad5) cause mild or asymptomatic infections, and genetic modifications can inhibit their replication.
Acute bronchitis and bronchiolitis stem from HAdVs, accounting for 5-18% of these conditions in infants.

Other manifestations include fever, sore throat, diarrhea, vomiting, and conjunctivitis.
Severe manifestations like pericarditis have occurred, particularly associated with Ad7, including immune complexes identified in infected lymphoid follicles.
HAdVs linked to appendicitis and mesenteric lymphadenitis, often with right iliac fossa pain and acute respiratory symptoms.

Advances in structural biology (e.g., cryo-electron microscopy) have improved understanding of adenovirus organization.
Ongoing studies are necessary to clarify the pathology connected to severe dilated cardiomyopathy (DCM) and other complications associated with HAdV infections.

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