Medical Microbiology & Immunology Department NON-ENVELOPED DNA VIRUSES Ain Shams University Faculty of Medicine Medical Microbiology & Immunology Department NON-ENVELOPED DNA VIRUSES  Adenoviruses Done by: Dr/ Makram F. Attalah

Adenoviruses Outline General Properties of Adenovirus Clinical Diseases Transmission Diagnosis Prevention and Control

Adenoviruses are a group of viruses that infect the m Adenoviruses are a group of viruses that infect the m.membranes of the respiratory tract, eyes, intestines and urinary tract. Some persist as latent infection for years in the adenoids and tonsils and hence the name adenovirus.

Adenoviruses First isolated in 1953 in a human adenoid cell culture. Approximately 100 serotypes have been recognized, at least 49 of which infect humans. Have been classified into six subgroups (A - F) based on their physical, chemical and biological properties.

Adenoviruses The first human adenoviruses to be identified, numbered 1 to 7, are the most common. Respiratory tract infection, conjunctivitis (pinkeye), hemorrhagic cystitis, and gastroenteritis. Several adenoviruses have oncogenic potential in animals and for this reason have been extensively studied by molecular biologists.

Viral Structure They are medium sized non-enveloped ds DNA viruses. They have icosahedral capsid with fibers topped with knobs projecting from it. These fibers are the site of attachment to target cells. They are associated with hemagglutinating activity and they contain type specific antigens that are important in serotyping.

Reaction to Chemical and Physical Agents Adenoviruses are unusually stable to chemical or physical agents and adverse pH conditions, allowing for prolonged survival outside of the body.

They do not spread beyond regional lymph nodes. Mode of Transmission Inhalation, direct contact, contaminated eye equipments, and fecal-oral route. Infect epithelial cells lining the oropharynx, the respiratory and enteric organs They do not spread beyond regional lymph nodes.

Pathogenesis and Immunity Adenoviruses infect and replicate in epithelial cells of the respiratory tract, eye, intestine, urinary bladder and liver. Has a propensity to become latent and persist in lymphoid and other tissue, such as adenoids, tonsils and Peyer's patches, and can be reactivated in immunosuppressed patients. Although certain adenoviruses (groups A and B) are oncogenic in hamster, adenovirus transformation of human cells has not been observed.

Clinical Manifestations Conjunctivitis acute folicular conjunctivitis epidemic keratoconjunctivitis Pharyngitis- acute febrile Pneumonia- sequalae Cystitis Infantile Gastroenteritis

Clinical Syndromes Respiratory Diseases: Adenoviruses primarily infect children and less commonly infect adults. Respiratory Diseases: 1. Febrile respiratory disease (common cold syndrome): It is the usual manifestation of symptomatic adenoviral infection in children. Affected children have fever, pharyngitis, runny nose, and dry cough. 2. Acute Respiratory Disease (ARD) syndrome: It is observed in military recruits. ARD is marked by malaise, fever, chills, and headache. Respiratory manifestations include pharyngitis, cough, and sometimes progress to pneumonia. 3. Viral pneumonia of infants. 4. Nosocomial pneumonia in hospitalized children.

Eye Infections: 1. Conjunctivitis without constitutional symptoms. 2.Acute Pharyngoconjunctival (APC) fever (swimming pool conjunctivitis): Outbreaks have been associated with use of inadequately chlorinated swimming pools and small lakes. There is clinical triad of fever, pharyngitis, and conjunctivitis. 3. Epidemic Keratoconjunctivitis (EKC): It is a more serious disease that occurs mainly in adults and is highly infectious. The disease is characterized by acute conjunctivitis followed by keratitis that may leave corneal opacities.

GASTROENTERITIS AND DIARRHEA Major cause of acute viral gastroenteritis; 15% of the cases of gastroenteritis in hospitalized patients. Serotypes 40 to 41 appear to be responsible for episodes of diarrhea in infants.

Acute hemorrhagic cystitis in children, mainly boys. Urinary Tract Infection: Acute hemorrhagic cystitis in children, mainly boys. Severe Infections in Immunocompromized: Fatal pneumonia in transplant patients. Hepatitis in liver allograft in children with liver transplant. AIDS patients may suffer adenovirus infection especially gastroenteritis.

Laboratory Diagnosis Specimens: Throat swabs, conjunctival swabs, urine, stools and rectal swabs. 1. Direct Virus Demonstration: a. E/M: can be used to detect the virus in stool specimens. b. PCR: to detect viral DNA.

2. Viral Isolation: Specimens are inoculated on human epithelial cell lines. The virus grows slowly and produces characteristic CPE in the form of clusters of large rounded or ballooned cells like bunches of grapes. Isolates are identified by IFT. Specific serotypes are identified by Nt and HI tests. Since adenovirus can be excreted for prolonged periods, the presence of virus does not necessarily mean it is associated with disease.

3. Serology: Detection of fourfold or greater rise in complement-fixing antibody titer indicates recent infection by any type of adenovirus.  Nt and HI tests can detect antibodies to a specific serotype.

Treatment, Prevention, and Control There is no approved treatment for adenovirus infection. Avoid overcrowding. Chlorination of swimming pools. Adequate sterilization of solutions and equipments used in eye examination. Live attenuated vaccine with adenovirus types 4 and 7 : Available only for preventing ARD among military recruits. Given orally in the form of gelatin-coated capsules.

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Pop Exam Adenoviruses have been implicated in many diseases except: A- respiratory infection B- venereal diseases C- pharynoconjuctival fever D- keratoconjunctivitis E- gastroenteritis