Adenovirus: what is it?

Adenoviruses are a family of virus at DNA without envelope, which includes five genera, one of which (mastadenovirus) affects humans. Human adenoviruses are themselves divided into seven subgroups (A to G) and 67 serotypes.

Diseases caused by adenoviruses

Most adenoviruses cause asymptomatic infections, but some (such as serotypes 40 and 41) cause gastroenteritis acute in children. Enteric adenoviruses represent 9% of cases of diarrhea in children, and are the third leading cause of infantile gastroenteritis after the rotavirus and the norovirus.

Adenoviruses of serotypes 3, 7 and 8 cause conjunctivitis, keratoconjunctivitisa pharyngitis and some fever.

In immunocompromised patients, adenoviruses can cause serious illness (pneumoniameningoencephalitis, hepatitis, etc. potentially fatal.

Structure of Adenoviruses

Adenoviruses are medium-sized DNA viruses (70–90 nm in diameter), with a genome from 30,000 to 45,000 base pairs (i.e. about forty Genoa). The viral particle is surrounded by a capsid of icosahedral structure. The main protein of the capsid are:

• the hexon: located on the faces, it carries the antigens which are used by the immune system to recognize the virus;
• the penton: located at the top, it is cytotoxic ;
• fibers: located on the spicules, they are used by the virus to attach itself to the membrane of the target cell.

Adenovirus and vaccination

Adenoviruses are considered excellent viral vectors for transporting antigens from other viruses around the body, due to their ability to induce innate and adaptive immune responses. The virus is rendered harmless (attenuated or killed), or from a variety that does not affect humans.

The vaccines adenoviruses are used against a wide variety of pathogens, including bacillus of the tuberculosisHIV, falciparum plasmodium (responsible for malaria) where the SARS-CoV-2.

Adenoviruses also serve as a viral vector in gene therapies, where a piece of gene for therapeutic purposes is introduced into a cell. As such, adenoviruses are likely to trigger uncontrolled inflammatory reactions, but such incidents remain rare.