ADENOVIRUSES:DOUBLE STRANDED DNA VIRUSES.pptx

adenoviruses

1. ADENOVIRUSES DR.FARIA ASHRAF

2. HUMAN ADENOVIRUSES Adenoviruses were first isolated in 1935 from human adenoid tissues . Since then, more than 50 distinct antigenic 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 .

3. WHAT ARE ADENOVIRUSES Adenoviruses are a group of medium sized, non enveloped , double stranded DNA viruses that share a common complement fixing antigen They infect both humans and animals 

4. CLASSIFICATION Adenoviruses are divided into six groups (A to F) based on: • physical, • chemical • biological properties Antigenic structure divides adenoviruses into: - 52 serotypes: - About 1/3 of the 52 known human serotypes are responsible for most cases of Adenovirus disease.

5. MORPHOLOGY Adenovirus are 70-75 nm in size The capsid contains 252 capsomeres arranged as icosahedrons with 20 triangular facets and 12 vertices 240 are called as hexons 12 are called as pentons .

6. Each penton unit consists of penton base anchored in the capsid and projection or fibre consists of a rod like portion with a knob attached at the distal end The virus appears like a space vehicle.

7. Adenoviruses are medium-sized (90–100 nm), non enveloped (naked) icosahedral viruses composed of a nucleocapsid and a double-stranded linear DNA genome. There are over 52 different serotypes in humans, which are responsible for 5–10% of upper respiratory infections in children, and many infections in adults as well. 

8. WORLDWIDE DISTRIBUTION Over 50 serotypes are isolated Most of the recent isolates are from AIDS patients Infections are common in children and world wide prevalence .

9. CLASSIFICATION Contain two genera Mast adenovirus-Infects the mammals • Aviaadenovirus - Infects birds • Type 12, 18,and 31 cause sarcoma when injected into new born hamsters. 

10. PATHOGENESIS Adenovirus cause infections in Respiratory tract Eye, Urinary bladder, and Intestines More than one type of virus may cause clinically different diseases

11. CLINICAL FEATURES Adenoviruses most commonly cause respiratory illness; however, depending on the infecting serotype, they may also cause various other illnesses, such as gastroenteritis, conjunctivitis, cystitis, and rash illness. Symptoms of respiratory illness caused by adenovirus infection range from the common cold syndrome to pneumonia, croup, and bronchitis.

12. 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. Four different syndromes of respiratory infection have been linked to Adenoviruses . 1. Acute febrile pharyngitis : most commonly seen in infants and young children , symptoms include cough, stuffy nose, fever and sore throat. 2.Pharyngoconjunctival 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. 3.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 4.Pneumonia : a complication of acute respiratory disease in both children and adults.

15. Adenoviruses are responsible for 3-5% of acute respiratory infections in children and 2% of respiratory illnesses in civilian adults. They are more apt to cause infection among military recruits and other young people who live in institutional environments. Outbreaks among children are frequently reported at boarding schools and summer camps

16. PHARYNGITIS Major cause of infections associated with nonbacterial pharyngitis and tonsillitis Causes febrile common cold Types 1 – 7 are common types

17. PNEUMONIA Adenovirus types 3 and 7 are associated with pneumonia resembles like atypical pneumonia in adults . Type 7 causes serious and even fatal pneumonia in infants and young children

18. ARD  Occurs usually in military recruits Serotypes 4,7,and 21 are agents commonly associated.

19. PHARYNGOCONJUNCTIVAL FEVER Occurs in civilian population manifest with syndrome of febrile p haryngitis and conjunctivitis Serotypes 3, 7, and 14 are associated.

20. EPIDEMIC KERATOCONJUNCTIVITIS Occurs as a serious epidemic Caused by serotypes 8, and less frequently with 19, and 37. 

21. OTHER MANIFESTATIONS Acute follicular conjunctivitis, types 3,4 and 11 are responsible Adenoviral and chlamydial conjunctivitis are clinically similar Diarrhoea – not conclusively established Acute haemorrhagic cystitis in children and types 11 and 21 are responsible Mesenteric adenitis and intussusceptions in children.

22. DIAGNOSIS Diagnosis : Virus isolation Serology(Antigen detection) P olymerase C hain R eaction assay can be used to identify adenovirus infections. Adenovirus typing is usually accomplished by Hemagglutination -inhibition and/or neutralization with type-specific antiserum.

23. LABORATORY DIAGNOSIS Direct detection: Virus particle by EM can be detected by direct examination of fecal extracts Detection of adenoviral antigens by ELISA . Enteric Adenoviruses Detection of adenoviral NA by Polymerase chain reaction: can be used for diagnosis of Adenovirus infections in tissue samples or body fluids.

24. Contd … • Isolation : depending on the clinical disease, the virus may be recovered from throat, or c onjunctival swabs or and urine. • Isolation is much more difficult from the stool or rectal swabs 

25. TREATMENT  Treatment of adenovirus infections is usually supportive and aimed at relieving symptoms of the illness. Bed rest may be recommended along with medications to reduce fever and/or pain . (Aspirin should not be given to children because it is associated with Reye's syndrome.) 

26. Eye infections may benefit from topical corticosteroids to relieve symptoms and shorten the course of the disease. Hospitalization is usually required for severe pneumonia in infants and for keratoconjunctivitis (to prevent blindness). 

27. PROPHYLAXIS Prevention: Vaccines were developed for adenovirus serotypes 4 and 7, but were available only for preventing ARD among military recruits. Strict attention to good infection-control practices is effective for stopping nosocomial outbreaks of adenovirus-associated disease, such as epidemic keratoconjunctivitis . Maintaining adequate levels of chlorination is necessary for preventing swimming pool-associated outbreaks of adenovirus conjunctivitis.

28. PREVENTION/CONTROL Careful hand washing is the easiest way to prevent infection . Disinfection of environmental surfaces with hypochlorite. 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.

29. EMERGING TOOL IN GENETIC ENGG Adenovirus vectors are used by researchers to deliver genetic material into the cells. Not only is this but they also being used by molecular biologists for vaccination purposes. They are mostly used in in-vitro experiments at this time

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