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Enterovirus

Enterovirus. Enteroviruses constitute a major subgroup of small RNA viruses (picomaviruses) that readily infect the intestinal tract. They are subclassified into polioviruses coxsackieviruses echoviruses rhinoviruses. Enteroviruses are small, single-stranded RNA viruses

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Enterovirus

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  1. Enterovirus

  2. Enteroviruses constitute a major subgroup of small RNA viruses (picomaviruses) that readily infect the intestinal tract.

  3. They are subclassified into • polioviruses • coxsackieviruses • echoviruses • rhinoviruses

  4. Enteroviruses are small, single-stranded RNA viruses • Replication and assembly takes place in cytoplasm

  5. Resistant to acid, detergents, and many disinfectants • Formaldehyde and hypochlorite are active against enteroviruses

  6. Human diseases caused by enteroviruses Coxsackie A virus Coxsackie B virus Echovirus Enterovirus (other) Asymptomatic infection yes yes yes yes Meningitis yes yes yes yes Paralysis yes yes yes no Febrile exanthems yes yes yes yes Acute respiratory disease yes yes yes yes Myocarditis yes yes yes no Orchitis no yes yes no

  7. POLIOVIRUS paralytic poliomyelitis

  8. Biology • Small positive-sense single-stranded RNA virus • no a lipid membrane

  9. naked icosahedral nucleocapsid • rapidly inactivated by heat, formaldehyde, chlorine, and ultraviolet light.

  10. Pathogenesis and immunology

  11. In spinal paralysis one or more limbs may be affected or complete flaccid paralysis may occur. In bulbar paralysis cranial nerves and the respiratory center in the medulla are affected leading to paralysis of neck and respiratory muscles. no sensory loss iron lung

  12. Diagnosis • Demonstration of the virus: Virus may be recovered from faeces (also throat swabs), by inoculation of cell cultures and recognition of cytopathic effects with confirmation by neutralisation of infectivity with specific antisera.

  13. Molecular nucleic acid techniques : RT-PCR, nucleic acid hybridization

  14. Serology: Detection of specific IgM has not been applied to polio diagnosis. Antibodies are traditionally tested by micro-neutralisation of infectivity in vitro using antisera to known virus strains.

  15. Prevention and therapy • sIgA • Sabin (attenuated) vaccine OPV • Salk (inactivated) vaccine IPV

  16. Coxsackieviruses and Echoviruses • they have a greater tendency to affect the meninges and occasionally the cerebrum, but only a few affect anterior horn cells

  17. Coxsackieviruses can be divided into two groups :A and B . • Group A coxsackieviruses cause hand-foot-mouth disease , herpangina

  18. Hand, foot and mouth disease • This is an exanthem (that is, a rash) caused by Coxsackie type A16. Symptoms include fever and blisters on the hands, palate and feet. Again, it subsides in a few days.

  19. The structure of echoviruses is similar to that of polioviruses. 34 serotypes have been isolated.

  20. Echoviruses cause a variety of diseases such as aseptic meningitis, upper respiratory infection, febrile illness with and without rash, infantile diarrhea, and hemorrhagic conjunctivitis.

  21. Enterovirus 70 cause acute hemorrhagic conjunctivitis. Enterovirus 71 causes viral central nervous system disease, including meningitis, encephalitis, and paralysis.

  22. Gastroenteritis-related Viruses A number of different viruses cause diarrhoea, which are named viral gastroenteritis ,of which the most important is rotaviruses.

  23. ROTAVIRUSES • icosahedral symmetry • two concentric protein shells, or capsids • 60-80nm wheel with radiating spokes (Latin, rota = wheel) • double stranded (ds) RNA in 11 segments

  24. Properties • Rotavirus is stable in the environment and is relatively resistant to handwashing agents. Is susceptible to disinfection with 95% ethanol, ‘Lysol’, formalin and in environments with pH<2

  25. Rotaviruses can be divided into 5 group depended on the genome patterns. Group A is the main human pathogens. • Human rotavirus has proved difficult to culture in vitro.

  26. Rotavirus is transmitted by the typical faecal-oral route. • Rotavirus infection is characterized by nausea, watery diarrhoea, with or without vomiting.

  27. Pathogenesis and immunology • Age :Older infants and young children (4 months - 2 years) • Diarrhea : watery (no blood or leukocytes), lasting 3-9 days • Many cases and outbreaks are nosocomial

  28. Contagious Period- Before onset of diarrhea to a few days after end of diarrhea • Immunity to rotavirus infection is unclear: intestinal IgA directed against specific serotypes protects against reinfection.

  29. Diagnosis • Rapid diagnosis - antigen detection in stool by ELISA (uses a monoclonal antibody) and LA. • Electron microscopy

  30. Prevention and therapy • Prevention of spread: Handwashing with good technique Disinfection of surfaces, toilets, toys .

  31. Treatment: ★Supportive - rehydration (oral / intravenous) ★Antiviral agents not known to be effective ★Vaccine: Live tetravalent rhesus-human reassortant vaccine (Rotashield) was first licensed for use in infants in August 1998

  32. Enteric adenovirus • Adenovirus serotypes implicated in gastroenteritis are 40, 41, 31, 3, 7. • diarrhea disease in infants and children <4 years of age. • spread by the fecal-oral route and is not shed in the nasopharynx

  33. ★ ssRNA viruses including Norwalk virus, 33 nm in size ★ “classic ” human calicivirus ★ small round structure virus (SRSV) Calicivirus

  34. Astrovirus • +ssRNA • non-enveloped • unbroken surface “5 or 6 pointed star”

  35. thank you !

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