Sporadic cases and occassional outbreaks of diarrhea
Infections are mild
Infants, young children and elderly most affected
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
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)
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
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
True or False. Only the innate immune system provides protection against the rotavirus.
False. B cells, T cells and interferons provide protection.
Which antibodies and T cells provide the most protection against the rotavirus?
Antibodies: IgA and IgG
T cells: CD4+ T cells
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
Which of the following is incorrect regarding the pathogenesis of the norovirus?
G) D and F, norovirus has high resistance to freezing and high temperatures, and the incubation period is normally 12-48 hrs.
Which of the following is incorrect with regards to the properties of the norovirus?
G) A and C, norovirus is a member of the caliciviridae family and posses ss +RNA
True or False. Only the CD4+ T cells provide protection against the norovirus.
False, CD4+ and CD8+ provide protection against the norovirus.
What is the best way to prevent the spread of norovirus infection?
HAND WASHING WITH SOAP AND WATER!
What is hepatitis?
Inflammation and damage of the liver caused by many different viruses.
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.
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
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)
Name 6 viruses that can cause sporadic hepatitis.
1) EBV
2) CMV
3) HSV
4) Yellow fever virus
5) Rubella virus
6) Enteroviruses
True or false. Many of the symptoms of acute hepatitis are due to the damage and cytolysis of liver cells.
True
True or false. Destruction of hepatocytes occur by direct cytolytic effect by virus or indirectly by immune response to infection.
True
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.
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
Name 3 particle mrphologies of HBV.
1) Fully mature and infectious virion (Dane particle)
2) 20 nm sphere
3) Filamentous particles of variable length
What is the name of the HBV surface antigen?
HBsAg
What is the name of the HBV core antigen?
HBcAg
Name an indicator of recent HBV infection?
IgM antibodies to HBcAg
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
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
What are the 2 best ways to prevent and treat HBV?
1) Recombinant vaccine
2) Interferon-alpha or HBV polymerase inhibitors
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
Which hepatitis virus is the most common cause of infectious jaundice in the world?
HAV
True or false. HAV is a very stable picornavirus and can survive for years in a freezer.
True
What is the incubation period for HAV?
about 1 month
What is the best way to prevent the spread of HAV?
Havrix vaccine (inactivated virus)
Which of the following hepatitis viruses matches this statement: part of the hepeviridae family?
A) Hep E
Which of the following hepatitis viruses matches this statement: part of the a flavivirus?
D) Hep F and G
Which of the following hepatitis viruses matches this statement: may be carried by wild rats, pigs, and deer?
A) Hep E
Which of the following hepatitis viruses matches this statement: slows down the progression of HIV and prolongs survival of AIDS patients?
