Brief description about Adenoviruses

1. Adenoviruses
Made By : Niteesh Kumar

2. Introduction
Adenoviruses is a group of medium sized, nonenveloped, double
stranded DNA viruses that replicate and produce disease in the eye
and in the respiratory, gastrointestinal and urinary tracts.
They infect humans and animals.
At least 47 serotypes associated with human diseases.
• Most infections asymptomatic;
• Infections are common in children;

3. Morphology
1. They are non-enveloped, 70-90 nm in size, possess 252
capsomeres.
2.Icosahedral symmetry with fibre proteins projecting from
each vertex ( unique property): This gives a typical space
vehicle shaped appearance .
3. They contain a linear dsDNA

6. Pathogenesis
Adenoviruses infect and replicate in the epithelial
cells of the respiratory tract, eye, gastrointestinal tract,
urinary bladder and liver. Though one-third of the
serotypes can cause human diseases, types 1-7 are most
common worldwide. Single serotype may cause different
manifestations and conversely, more than one type may
cause the same clinical illness.

8. Clinical Manifestations
Respiratory diseases
• Upper respiratory tract infection in children-mainly caused by
serotypes 1, 2, 3 and 5
• Pneumonia: Adenoviruses particularly types 3, 7, and 21 are
responsible for about 10-20% of pneumonia in childhood.
• Acute respiratory disease syndrome outbreaks among military
recruit-are commonly associated with type 4, 7 and
occasionally type 3.

11. Ocular infections:
• Pharyngoconjunctival fever: It tends to occur in
outbreaks, at children's summer camps (also called swimming pool
conjunctivitis), and is associated with types 3 and 7.
• Epidemic keratoconjunctivitis or shipyard eye:
It occurs mainly in adults and is highly contagious,
caused by types 8, 19 and 37.

12. Epidemic keratoconjunctivitis

13. Infantile gastroenteritis: Serotype 40 and 41 may account for 5-15%
of cases of viral gastroenteritis in young children.
Acute haemorrhagic cystitis in children, especially in boys-caused
by serotypes 11 and 21.
Immunocompromised patients are at higher risk of
developing serious pneumonia.
Transplant recipients may develop pneumonia, hepatitis, nephritis,
colitis, encephalitis and haemorrhagic cystitis. Types 34 and 35 are
isolated commonly from transplant recipients.

14. Laboratory Diagnosis
Specimen collection: Depending on the manifestations, various
specimens such as throat swab, conjunctival swab, stool or
urine may be collected.
Virus isolation: Primary human embryonic kidney cell line and A549
cell line are the most susceptible cell lines. Others such as HEp-2,
HeLa, and KB cell lines can also be used
 Viral growth can be detected by:
• Characteristic cytopathic effect: Rounding and
grape-like clustering of swollen cells
• Antigen detection by direct-IF test.

15. This digitally-colorized transmission electron microscopic
(TEM) image revealed some of the ultrastructural details
exhibited by a small cluster of adenovirus virions.

17. • Reporting: Reporting should be done cautiously when adenovirus
is recovered from throat or stool as they can persist for long
duration in the gut and in adenoids and shed intermittently
in the setting of other infections.
• Shell vial technique can be performed prior to cell culture to enhance
viral replication so that detection time can be reduced
• Explant culture: Adenoviruses (especially group-C) can grow on
adenoid explants, however, it is no longer in use now.
 Serotyping: Type specific antigens ( viral capsid proteins) can be
identified by hemagglutination test ( targeting HA antigens) and
neutralization test (targeting capsid proteins)

18. Direct-IF test: It can be employed to detect adenoviral
antigens from clinical samples such as throat or
conjunctival secretions by using fluorescent tagged antihexon
Antibody.
Fastidious enteric serotypes such as type 40 and 41 from
stool: They can be detected by electron microscopy or by
antigen detection by ELISA.

20.  Molecular methods: PCR has been available targeting group
-specific conserved hexon or fibre genes. Multiplex PCR followed
by sequencing is done for detection of adenovirus types.
PCR is rapid and more sensitive than conventional culture.
Real-time PCR is used to monitor viral load, which is useful
for immunocompromised and transplant recipients.
 Serum antibody detection: It can be done by various tests
such as CFT, neutralization test, ELISA, or rarely hemagglutination
inhibition test (HAI) for few hemagglutinating serotypes.

21. This transmission electron microscopic (TEM) image
reveals some of the ultrastructural morphology exhibited
by two adenovirus-2 virions.

22. Treatment and Control
There is no specific antiviral drug available. Only
symptomatic treatment is given.
General Preventive Measures
1. Effective hand washing: Use of paper towels is better than
cloth towels for hand drying
2. Sodium hypochlorite to disinfect environmental surfaces
3. Chlorination of swimming pools and waste water should
be followed to prevent waterborne conjunctivitis or gastroenteritis.
4. Strict asepsis during eye examinations

23. Live Adenovirus Vaccine
Live adenovirus vaccine containing types 4 and 7 has been used in military
recruits. It was available as gelatin coated capsules and given orally
It was highly effective, but not in use since 1999 due to manufacturer
issues. There are plans to develop this vaccine again.
Adenoviruses used for Gene Therapy
Replication defective adenoviruses can also be used as live virus
vectors for the delivery of vaccine antigens and for gene therapy;
e.g. trials on adenovirus vectored M. tuberculosis (using SSA antigen)
and HIV vaccines.

24. THANK YOU MA’AM