• Non-enveloped linear ds-DNA virus.
    Icosahedral symmetry (70-90 nm diameter).
    The capsid has three major protein – hexon, penton, and fibre.
  • Adenovirus is being investigated as a vector for vaccine and gene therapy.
  • Ubiquitous in nature. Most people are seropositive by the age of 10 years.
  • Adenovirus can be divided into 4 genera. Mammalian adenovirus belongs to the genus Mastadenovirus. Human adenovirus is a part of this genera.

Adenovirus receptors

Coxsackie B virus–adenovirus receptor (CAR),
CD46, CD80, CD86
Sialic acid, heparan sulfate proteoglycans.

Viral replication

Viral replication occurs in the nucleus.

Genus Mastadenovirus has 7 species based on their haemagglutination character. Each species was divided into serotypes based on neutralisation.

At present genotyping is being used to classify Adenovirus.

Different species of Mastadenovirus has different tissue tropism.

AGI, respiratory, urinaryBEye, GI, respiratory, urinary
CGI, respiratory, urinaryDEye, GI
EEye, respiratoryFGI
GGI

During the replication process virus releases protein to modulate the immune system –
Inhibit MHC-1 expression
Downregulation of fas, TNF
Inhibition of apoptosis (TRAIL receptor)

Latent infection-

Adenovirus can remain latent in the T-lymphocytes of tonsil and adenoid.

 

Route on transmission:

Droplet, faeco-oral.

Adenovirus infection:

Adenovirus is commonly seen in 3 groups – children, immunocompromised and military recruits.
50% of adenovirus infection is asymptomatic.

Up to 10% of febrile illness in children are due to adenovirus.

Laboratory diagnosis:

Culture:
Not readily available.
Serotype 40,41 – cannot be cultured.
The patient may shed virus for days to a couple of weeks, but an immunocompromised patient may shed virus much longer.

Serology:
Immunofluorescence assay – low sensitivity (40-60%), less in an immunocompromised patient.
ELISA – fourfold rise in titre is used to diagnose infection.

PCR:
Commonly used.
Quantitative PCR can be used to measure treatment response.

Typing:
Haemagglutination
Neutralisation,
Whole-genome sequencing,
Phylogenetic analysis.

Histopathology:
Typical finding, smudge cell.

Treatment:

Immune reconstitution – reduction in immunosuppression.

Cidofovir:
In vitro activity.
Limited clinical data.
Toxicity – nephrotoxic, GI.
The oral liposomal formulation is being trialled.

Ribavirin:
Limited clinical data.
Active against group C.

Vidarabine:
Limited clinical data.

Ganciclovir:
Limited clinical data.

Immunotherapy:
Adoptive T-cell therapy
Investigational.

 

Vaccine:

A vaccine has been developed for military recruits.

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