ADENOVIRUSES

1. ADENOVIRUSES Human Adenoviruses

2. DNA VIRUSES All are DS except Parvoviridae All replicate in the nucleus except Poxviridae Icosahedral Complex 1- Poxviridae Naked Enveloped non-enveloped ether-sensitive ether-resistant 1- Parvoviridae 1- Herpesviridae 2- Papillomaviridae 2- Hepadnaviridae 3- Polyomaviridae 4- Adenoviridae

3. Human Adenoviruses • Adenoviruses were first isolated in 1935 from human adenoid tissues. • Since then, at least 49 distinctantigenic types have been isolated from humans and many other types from animals. • All human serotypes are included in a single genus within the family Adenoviridae.

5. Morphology • ds-DNA viruses, • media sized in diameter, • icosahedral • Nonenveloped Antigenic structure • All human Adenoviruses share a common group-specific antigen. • Type specific antigens are important in serotyping.

6. Classification Adenoviruses are divided into six groups (A to F) based on: • physical, • chemical • biological properties Antigenic structure divides adenoviruses into: - 49 serotypes: - About 1/3 of the 49 known human serotypes are responsible for most cases of Adenovirus disease.

7. Pathogenesis: • Adenoviruses spread by: • direct contact, • respiratory droplets • feco-oral route.

8. Pathogenesis: • Adenoviruses infect and replicate in the epithelial cells of the: • pharynx, • conjunctiva, • urinary bladder • small intestine. They usually do not spread beyond the regional lymph nodes EXCEPT IN THE IMMUNE COMPROMIZED HOST.

9. Pathogenesis: • The virus has a tendency to become latent in lymphoid tissue, • The virus can be reactivated by immunosuppression.

10. Clinical Syndromes: • Adenoviruses cause primary infection in: • children • less commonly adults. • Several distinct clinical syndromes are associated with Adenovirus infection.

11. CLINICAL SYNDROMES A. Respiratory diseases: B. Eye infections: C. Gastrointestinal disease D. Other diseases: E. Adenoviral infections of the immune compromised host

12. A. Respiratory diseases: • The most important etiological association of adenoviruses is with the respiratory diseases. • They are responsible for 5% of acute respiratory diseases in: • young children • and much less in adults.

13. A. Respiratory diseases: Four different syndromes of respiratory infection have been linked to Adenoviruses. • Acute febrile pharyngitis: • most commonly seen in infants and young children, • symptoms include cough, stuffy nose, fever and sore throat. • Pharyngo conjunctival fever: • symptoms are similar to those of acute febrile pharyngitis but conjunctivitis is also present. • It tends to occur in outbreaks such as at children's summer camps (swimming pool conjunctivitis).

14. A. Respiratory diseases: • Acute respiratory disease: • is characterized by pharyngitis, fever, cough and malaise. • It occurs in an epidemic form among young recruits under conditions of fatigue and overcrowding • Pneumonia: a complication of acute respiratory disease in both children and adults.

15. NOTE Outbreaks & epidemic adenovirus infections • Pharyngo conjunctival fever: • outbreaks • in children's summer camps (swimming pool conjunctivitis). • Acute respiratory disease: • occurs in an epidemic form • among young recruits • Epidemic keratoconjunctivitis:

16. B. Eye infections: • Mild conjunctivitis: • can occur as a part of respiratory pharyngeal syndromes. • Complete recovery with no lasting sequelae is the common outcome. • Can occur sporadically or in outbreaks. • Epidemic keratoconjunctivitis: • a highly contagious and a more serious disease occurring mainly in adults. • Corneal involvement may be followed by various degrees of visual disability.

17. C. Gastrointestinal disease: • No disease association • Many Adenoviruses replicate in intestinal cells and are present in the stools without being associated with GIT disease. • Infantile gastroenteritis • Two serotypes (40, 41) have been etiologically associated with infantile gastroenteritis.

18. NOTE • The enteric Adenoviruses are very difficult to cultivate. • Lab diagnosis depend on direct detection

19. D. Other diseases: • Acute haemorrhagic cystitis: • types 11, 21 may cause acute haemorrhagic cystitis in children especially boys.

20. E. Adenoviral infections of the immune compromised host • The most common clinical manifestations are: • pneumonia, • hepatitis • gastroenteritis.

21. Laboratory Diagnosis • Direct detection: • Isolation • Serology

22. Laboratory Diagnosis Direct detection: • Virus particle byEM can be detected by direct examination of fecal extracts • Detection of adenoviral antigens byELISA. Enteric Adenoviruses • Detection of adenoviral NA by Polymerase chain reaction: can be used for diagnosis of Adenovirus infections in tissue samples or body fluids.

23. Laboratory Diagnosis Isolation • Isolation depending on the clinical disease, the virus may be recovered from throat, or conjunctival swabs or and urine. • Isolation is much more difficult from the stool or rectal swabs

24. Laboratory Diagnosis Serology • Haemagglutination inhibition & • Neutralization tests can be used to detect specific antibodies following Adenovirus infection.

25. Prevention and control • Careful hand washing is the easiest way to prevent infection. • Disinfection of Environmental surfaces with hypochlorites. • The risk of water borne outbreaks of conjunctivitis can be minimized by chlorination of swimming pools. • Epidemic keratoconjunctivitis can be controlled by strict asepsis during eye examination.