Viral Gastroenteritis (Dr. Yoshimura)

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davis.tiff
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167878
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Viral Gastroenteritis (Dr. Yoshimura)
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2012-08-31 14:26:22
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MICROBIOLOGY INFECTIOUS DISEASES
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MICRO/ID EXAM III
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  1. What is gastroenteritis?
    Inflammation of the lining of the intestine, leading to diarrhea
  2. True or False. More than half of all cases of chronic diarrheal disease are of viral origin.
    False. More than half of all cases of acute diarrheal disease are of viral origin.
  3. What is the time course of viral gastroenteritis and what causes the dehydration associated with it?
    Incubation period: 1-4 days and dehydration is caused by severe loss of electrolytes and fluids
  4. Reoviridae.
    Genome? Members of this family? Classification groups?
    • Genome
    • Segmented dsRNA
    • Members of this family
    • Rotavirus, orthoreovirus (affects animals)
    • Classification groups
    • Group A (Rotavirus)
    • Group B
    • Group C
    • Group D
  5. Adenovirus.
    Genome? Classification groups? Etiology/Pathogenesis?
    • Genome
    • DNA
    • Classification groups
    • Types 40 and 41
    • Etiology/Pathogenesis
    • Endemic diarrhea
    • Young children affected
  6. Caliciviridae.
    Genome? Members of this family? Etiology/Pathogenesis?
    • Genome
    • ss +RNA
    • Members of this family
    • Norovirus (including Norwalk virus)
    • Etiology/Pathogenesis
    • Acute, nonbacterial gastroenteritis
    • Older children and adults affected
  7. Astrovirus.
    Genome? Etiology/Pathogenesis?
    • Genome
    • ss +RNA
    • Etiology/Pathogenesis
    • Sporadic cases and occassional outbreaks of diarrhea
    • Infections are mild
    • Infants, young children and elderly most affected
  8. Rotavirus.
    Genome? Classification groups? Transmission? Sites of infection? Etiology/Pathogenesis?
    • Genome
    • Segmented dsRNA
    • Classification groups
    • Group A 
    • Transmission
    • Fecal-oral
    • Sites of infection
    • Tip of villi of small intestines
    • Etiology/Pathogenesis
    • Direct cellular damage
    • Impairment of sodium and glucose absorption
    • Acute onset of V/D
    • Activation of intestinal nerves leads to secretion of water
    • Predominates during winter season, symptomatic in children between 6 mos-2 yrs
  9. What are some general properties of rotaviruses? (specifically, structure and genome)
    • Structure
    • Uneveloped, icosahedral virus with a triple-layered protein capsid
    • Resistant to extreme ionic strengths, ranges of pH (2-9) and temperatures reaching 55 degrees Celsius
    • Genome
    • Linear, segmented dsRAA (11 segments)
  10. What is the life cycle of rotaviruses?
    Viral capsid (VP4) attaches to cellular receptors (sialic acid and integrins) > enters cells via receptor-mediated endocytosis > uncoating of the outer shell occuring in lysosome > -RNA strands are transcribed into +mRNAs by replicase > +RNA starnds are used for translation of viral proteins > new -RNA strands are synthesized during particle assembly > viral replicase synthesizes -RNA from +mRNAs > resulting in ds genome segments > newly synthesized capsid proteins enclose dsRNA segments and viral enzymes to form immature virus particles > cell lyses when virus particles are released
  11. What are 2 ways in which rotaviruses can be diagnosed in the laboratory?
    • 1) Immune electron microscopy, ELISA or immunoassay of stool sample
    • 2) Rise in titer of antibody to VP6
  12. True or False. Only the innate immune system provides protection against the rotavirus.
    False. B cells, T cells and interferons provide protection.
  13. Which antibodies and T cells provide the most protection against the rotavirus?
    • Antibodies: IgA and IgG
    • T cells: CD4+ T cells
  14. What are the 3 most effective ways to prevent and treat rotavirus infection?
    • 1) Water treatment and sanitation
    • 2) Vaccines
    • 3) Replacement of fluids and restoration of electrolyte balance via IV or PO
  15. Which of the following is incorrect regarding the pathogenesis of the norovirus?

    A) Can last on surfaces for days
    B) A and E
    C) Symptoms include N/V/D, chills headache, myalgia and fever
    D) Transmission is fecal-oral
    E) It is more common in the winter months
    F) Incubation period is 48-72 hrs
    G) D and F
    H) It is a highly contagious virus
    I) Has little resistance to freezing and high temperatures
    G) D and F, norovirus has high resistance to freezing and high temperatures, and the incubation period is normally 12-48 hrs.
    (this multiple choice question has been scrambled)
  16. Which of the following is incorrect with regards to the properties of the norovirus?

    A) A and C
    B) D and E
    C) Small, spherical particles with very stable capsid
    D) C and F
    E) Human noroviruses are not cultivatable
    F) Possess dsRNA
    G) A and E
    H) Synthesize replicase
    I) High degree of genetic variability
    J) It is a member of the reoviridae family
    A) A and C, norovirus is a member of the caliciviridae family and posses ss +RNA
    (this multiple choice question has been scrambled)
  17. True or False. Only the CD4+ T cells provide protection against the norovirus.
    False, CD4+ and CD8+ provide protection against the norovirus.
  18. What is the best way to prevent the spread of norovirus infection?
    HAND WASHING WITH SOAP AND WATER!
  19. What is hepatitis?
    Inflammation and damage of the liver caused by many different viruses.
  20. What are the most common clinical features associated with hepatitis? What are some other symptoms?
    Jaundice, abdominal pain, and fever. Other symptoms include lassitude, anorexia, weakness, N/V, headache, chills and dark urine.
  21. Compare and contrast acute and chronic hepatities.
    • Acute hepatitis
    • Temporary symptoms, but can lead to chronic hepatitis depending on the virus 
    • Chronic hepatitis
    • Lasts over a period of time and can result in liver tumors
  22. List the 5 different families that account for majority of hepatitis infection.
    • 1) Hep A (picornavirus)
    • 2) Hep B (hepadnavirus)
    • 3) Hep C (flavivirus)
    • 4) Hep D (viroid or satellite virus that requires HBV to replicate)
    • 5) Hep E (hepevirus)
  23. Name 6 viruses that can cause sporadic hepatitis.
    • 1) EBV
    • 2) CMV
    • 3) HSV
    • 4) Yellow fever virus
    • 5) Rubella virus
    • 6) Enteroviruses
  24. True or false. Many of the symptoms of acute hepatitis are due to the damage and cytolysis of liver cells.
    True
  25. True or false. Destruction of hepatocytes occur by direct cytolytic effect by virus or indirectly by immune response to infection.
    True
  26. True or false. Chronic infection by HAV can lead to cirrhosis and hepatic cellular carcinoma (HCC.)
    False, chronic infection of HBV and HCV lead to cirrhosis and HCC.
  27. Describe the pathogenesis of HBV infection.
    Transmission from sexual contact or exposure to infected blood or blood-products > primary infection which is typically asymptomatic > chronic infection which is typically symptomatic
  28. Name 3 particle mrphologies of HBV.
    • 1) Fully mature and infectious virion (Dane particle)
    • 2) 20 nm sphere
    • 3) Filamentous particles of variable length
  29. What is the name of the HBV surface antigen?
    HBsAg
  30. What is the name of the HBV core antigen?
    HBcAg
  31. Name an indicator of recent HBV infection?
    IgM antibodies to HBcAg
  32. Describe the viral genome of HBV.
    Circular DNA with a partial duplex molecule of 3.5 kb; unusal -DNA strand is full-length with the +DNA strand of variable length
  33. Describe the replication cycle of HBV.
    Attachment > Uncoating > Host DNA repair > transcription > translation and encapsidation > -DNA strand synthesis > +DNA strand synthesis > reenter cycle or acquire envelope to egress from host cell
  34. What are the 2 best ways to prevent and treat HBV?
    • 1) Recombinant vaccine
    • 2) Interferon-alpha or HBV polymerase inhibitors
  35. Hepatitis C Virus (HCV).
    Genome? Transmission? Incubation period? Treatment?
    • Genome
    • ss +RNA
    • Transmission
    • Blood transfusions, IV drug use, mother to child (not common), and sexual contact (small indication)
    • Incubation period?
    • 6-7 weeks
    • Treatment
    • Combination interferon-alpha and ribavirin
  36. Which hepatitis virus is the most common cause of infectious jaundice in the world?
    HAV
  37. True or false. HAV is a very stable picornavirus and can survive for years in a freezer.
    True
  38. What is the incubation period for HAV?
    about 1 month
  39. What is the best way to prevent the spread of HAV?
    Havrix vaccine (inactivated virus)
  40. Which of the following hepatitis viruses matches this statement: part of the hepeviridae family?

    A) Hep G
    B) Hep E and F
    C) Hep F
    D) Hep E
    E) None of the above
    D) Hep E
    (this multiple choice question has been scrambled)
  41. Which of the following hepatitis viruses matches this statement: part of the a flavivirus?

    A) Hep E
    B) Hep F
    C) Hep G
    D) Hep F and G
    E) None of the above
    D) Hep F and G
    (this multiple choice question has been scrambled)
  42. Which of the following hepatitis viruses matches this statement: may be carried by wild rats, pigs, and deer?

    A) Hep E
    B) Hep F
    C) Hep E and F
    D) Hep G
    E) None of the above
    A) Hep E
    (this multiple choice question has been scrambled)
  43. Which of the following hepatitis viruses matches this statement: slows down the progression of HIV and prolongs survival of AIDS patients?

    A) Hep G
    B) Hep E
    C) Hep F
    D) Hep E and F
    E) None of the above
    A) Hep G
    (this multiple choice question has been scrambled)

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