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Overview of Adenoviruses: Diseases, Characteristics, and Prevention

Adenoviruses are non-enveloped viruses causing various respiratory and gastrointestinal diseases such as pharyngitis, conjunctivitis, and pneumonia. They have unique characteristics like a toxic fiber protein and 41 antigenic types. Adenoviruses replicate in cells, leading to diseases like bronchitis and gastroenteritis, mainly affecting children. Diagnosis involves viral isolation and serologic tests, with no specific antiviral treatment available. Prevention includes live vaccines for military use against specific serotypes.

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Overview of Adenoviruses: Diseases, Characteristics, and Prevention

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  1. ADENOVIRUSES

  2. Adenoviruses (1953 from adenoids)  Disease: AV cause upper and lower respiratory diseases ◦ Pharyngitis ◦ Conjunctivitis ◦ Common cold & Pneumonia ◦ Keratoconjunctivitis ◦ Hemorrhagic cystitis ◦ Gastroenteritis

  3. Characteristics:  Non-enveloped, double stranded, linear DNA with icosahedral nucleocapsid  Only virus with fiber protruding from each of 12 vertics.  Fiber is toxic to human cells (when purified free from virions)  41 known antigenic types  Fiber protein is main type specific antigen  12, 18 & 31 serotypes of human adenovirus cause sarcomas at site of injection in lab rodents

  4. Replication  Fiber attaches to cells  virus penetrate, uncoat, viral DNA moves to nucleus.  DNA dependent RNA polymerase transcribes early genes  Splicing enzymes remove RNA representing introns  Early mRNA translate  nonstructural Protein in cytoplasm,after viral DNA replication in nucleus  Late mRNA transcribe and then translates structural virion protein.  Virus assembly occurs in nucleus,  Virus release by lysis of cell not by budding

  5. Transmission & epidemiology  Aerosol droplets, fecal-oral route  Disect inoculation of conjuntivas  Endemic worldwide,  Outbreak occurs in military people  Serotypes (3, 4, 7 & 21) cause respiratory disease in military recruits.  Type 8 & 19 keratoconjunctivitis  Type 40 & 41 cause infantile gasteroentritis cause epidemic

  6. Pathogenesis & immunity:  Adenovirus infect  mucosal epithelium ◦ Respiratory tract ◦ Gasterointestinal tract ◦ Conjunctivitis  Immunity based on neutralizing Ab  type specific and lifelong  In acute infection, after cell death, virus cause latent infection in Adenoidal and tonsillar tissue of throat

  7. Clinical findings  In pharyngoconjunctival fever, acute res.disease with fever,sore throat,Coryza.  In lower respiratory tract: Bronchitis, atypical Pneumonia,  Gasterenteritis with non bloody diarrhea occurs mainly in children younger than 2 years of age.  Approx. ½ of all asymptomatic. upper respiratory tract: Pharyngitis, AV infections are

  8. Diagnosis:  Isolation of virus in cell culture and detection of 4 fold rise inAb titer  Serologic tests base on complement fixation and hemmaglutination are mostly used Treatment:  No Antiviral treatment

  9. Prevention:  3 live, non-attenuated vaccine against serotypes 4, 7 & 21 are available but used only for military (not for civilian use)  Each of 3 vaccines are monovalent.  Viruses are administered separately because they interfere with each other when given together.  Vaccines are delivered in an enteric coated capsule to protect live virus from inactivation by stomach acid.

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