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Picornaviruses

Picornaviruses. Picornaviruses. Small ( pico ) RNA Naked capsid >230 members 5 genera. Picornaviruses. 5 genera Enterovirus Rhinovirus Heparnavirus Cardiovirus Aphtovirus. Picornaviruses. Enteroviruses At least 72 serotypes Polioviruses Coxsackieviruses Echoviruses.

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Picornaviruses

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  1. Picornaviruses

  2. Picornaviruses • Small (pico) • RNA • Naked capsid • >230 members • 5 genera

  3. Picornaviruses • 5 genera Enterovirus Rhinovirus Heparnavirus Cardiovirus Aphtovirus

  4. Picornaviruses • Enteroviruses At least 72 serotypes • Polioviruses • Coxsackieviruses • Echoviruses

  5. International Virus Taxonomi committee • Enterovirus genus (EV): Poliovirus and EV A, B, C and D. • Parechovirus cinsi (PeV): echovirus 22 ve 23

  6. Picornaviruses • Enteroviruses (EV) At least 72 serotypes • Polioviruses • Coxsackieviruses • Echoviruses • Human parechoviruses 1-3 (HPeV)

  7. Picornaviridae • Enterovirus • Poliovirus type 1, 2, and 3 • Coxsackie A virus types 1 to 22 and 24 • Coxsackie B virus types 1 to 6 • Echovirus (ECHO virus) types 1 to 9, 11 to 27, and 29 to 34 • Enterovirus 68 to 71 • Rhinovirus types 1 to 100+ • Cardiovirus • Aphtovirus • Heparnavirus • HAV

  8. Picornaviruses • Enteroviruses • Capsid very resistant facilitates transmission by the fecal-oral route • Infection initiated in the gastrointestinal tract • “Rarely cause enteric disease” • Infections are usually asymptomatic

  9. Picornaviruses/Replication • The specifity of the picornavirus interaction for cellular receptors is the major determinant of the target tissue tropism and disease • VP1 and “canyon” • 80% of rhinoviruses and several serotypes of of coxsackieviruses recognize ICAM-1 • polio a different molecule

  10. Enteroviruses/Pathogenesis&Immunity • The diseases produced by the enteroviruses are determined mainly by differences in tissue tropism and cytolytic capacity of the virus • Poliovirus with the narrowest tissue tropism recognize a receptor expressed on anterior horn cells of the spinal cord, dorsal root ganglia, motor neurons, skeletal muscle cells, and few other cells

  11. Enteroviruses/Pathogenesis&Immunity • Portal of entry: • URT • Oropharynx • Intestinal tract • Most enteroviruses are cytolytic • Excp: HAV • Viral shedding • From oropharynx • From the intestine (> 30 days)

  12. Enteroviruses/Pathogenesis&Immunity • “Antibody is the major protective immune response to the enteroviruses”

  13. Enteroviruses/Epidemiology • “The enteroviruses are exclusively human pathogenes” • Spread by the fecal-oral route • Asymptomatic shedding can occur • Poor sanitation and crowded living conditions foster transmission of the viruses • Enterovirus epidemics sewage contamination of water supplies • Outbreaks in schools & day care centers (summer) • Spread via resp. tract coxsackie & echov.

  14. Enteroviruses/Epidemiology • Poliovirus has been eliminated from the Western Hemisphere, but • “not from the world” • Polio cause more severe disease in late childhood, the adolescent years, or adulthood • Coxsackie A mor severe in adults than children • Coxsackie B & some echo“s” can be particularly harmful to infants

  15. Enteroviruses/Clinical syndromes • Poliovirus infections • Asymptomatic illness (90%) • Abortive poliomyelitis (minor illness) • Nonspecific febrile illness (5%) • Nonparalytic poliomyelitis or aseptic meningitis • 1 to 2%, symptomes of the minor illness + CNS sm • Paralytic polio, the major illness • 0.1 to 2.0%

  16. Enteroviruses/Clinical syndromes • Poliovirus infections • Paralytic poliomyelitis • Asymmetrical flaccid paralysis with no sensory loss • Poliovirus type 1 is responsible for 85% of cases • Vaccine-associated disease (reversion of type 2&3) • Recovery, within 6 months to 2 years • Bulbar poliomyelitis • More severe, 75% death, iron lungs (1950’s) • Postpolio syndrome (30-40 years later) in 20-80% of the original victims)

  17. Enteroviruses/Clinical syndromes Coxsackievirus and echovirus infections • Herpangina • Several types of Coxsackie A • Hand-foot-and-mouth disease( a vesicular exanthem) • Usually caused by coxsackievirus A16 • Pleurodynia (Bornholm’s disease)(Devil’s grip) • Fever + unilateral low thoracic, pleuritic chest pain • Coxsackie B

  18. Enteroviruses/Clinical syndromes Coxsackievirus and echovirus infections • Myocardial and pericardial infections* • Coxsackie B • Occur sporadically in older children and adults • Most threatening in newborns • Febrile illness, sudden unexplained onset of heart failure high mortality

  19. Enteroviruses/Clinical syndromes Coxsackievirus and echovirus infections • Viral (aseptic meningitis)* • Acute febrile illness + CNS symptoms • Petechia or a rash • Summer and autumn outbreaks with Echo 11 • Fever, rash and common cold-like symptoms • Other diseases • Acute hemorrhagic conjunctivitis • Enterovirus 70 and coxsackie A24

  20. Enteroviruses/Clinical syndromes Coxsackievirus and echovirus infections • Other diseases • Acute hemorrhagic conjunctivitis • Enterovirus 70 and coxsackie A24 • transplacental infection • Insulin-dependent diabetes • Coxsackie B

  21. PeV • Respiratory infections • Gastrointestinal infections

  22. Enteroviruses/Laboratory Diagnosis • Nükleic acit detection • Isolation • Serology: Antibody

  23. Enteroviruses/Treatment • Pleconaril new antiviral drug

  24. Enteroviruses/ Prevention & control “The prevention of paralytic polyomyelitis is one of the triumphs of modern medicine” Poliovirus vaccines: • IPV, developed by Jonas Salk • OPV, developed by Albert Sabin (live attenuated)

  25. 'Poliosuz Ülke Sertifikası’ • Rutin aşılama çalışmalarına ek olarak Ulusal Aşı Günleri (UAG) ve Mop-up gibi destek aşılamalar düzenlemesi gerekmiştir. • 1998 yılında tip 1 poliovirüse bağlı son çocuk felci vakası Ağrı ilinde saptanmıştır. • Bu vaka aynı zamanda DSÖ Avrupa bölgesi’nin de son polio vakası olmuştur. • Türkiye, Dünya Sağlık Örgütü Avrupa bölgesi ile birlikte 21 haziran 2002 tarihinde çocuk felci hastalığından (polio) arındırılmış olarak sertifikalandırılmıştır.

  26. Iron lung

  27. Polio sekeli

  28. Rhinoviruses • Most important cause of the common cold and URTI • ICAM-1 • Unable to replicate in the GIT • Labile to “ pH” • Grow best @ 33oC • Infection can be initiated by as little as 1 (one) infectious viral particle • “Runny nose”

  29. Rhinoviruses • Most important cause of URTI ~ 50% • Common cold: • Enteroviruses • Coronaviruses • Adenoviruses • Parainfluenza viruses

  30. Rhinoviruses • Common cold symptoms • Sneezing • Rhinorrhea nasal obstruction • Mild sore throat • Headache • Malaise • Cough • Fever & rigors

  31. Rhinoviruses • The clinical syndrome of the common cold is usually so characteristic that laboratory diagnosis is unnecessary!!

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