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

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Presentation on theme: "Enterovirus. Enteroviruses constitute a major subgroup of small RNA viruses (picomaviruses) that readily infect the intestinal tract. Enteroviruses constitute."— Presentation transcript:

1 Enterovirus

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

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5 Virus VirusSerotypes poliovirus1-3 Coxsackieivirus A 1-24 Coxsackievirus B 1-6 Echovirus1-34 New enterovirus Hepatitis A Virus 72 Rhinovirus>120

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

7 Resistant to acid, detergents, and many disinfectants Formaldehyde and hypochlorite are active against enteroviruses

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

9 POLIOVIRUS paralytic poliomyelitis

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11 Biology Small positive-sense single- stranded RNA virus Small positive-sense single- stranded RNA virus no a lipid membrane no a lipid membrane

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

13 Pathogenesis and immunology

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15 In spinal paralysis one or more limbs may be affected or complete flaccid paralysis may occur. 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. 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 no sensory loss iron lung

16 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.

17 Molecular nucleic acid techniques : Molecular nucleic acid techniques : RT-PCR, nucleic acid hybridization RT-PCR, nucleic acid hybridization

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

19 Prevention and therapy sIgA sIgA Sabin (attenuated) vaccine OPV Sabin (attenuated) vaccine OPV Salk (inactivated) vaccine IPV Salk (inactivated) vaccine IPV

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

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

22 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. 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.

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

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

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

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

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

28 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 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

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

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

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

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

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

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

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

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

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

38 Astrovirus +ssRNA +ssRNA non-enveloped non-enveloped unbroken surface unbroken surface “ 5 or 6 pointed star ”

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