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I & I Part II > Hepatitis Viruses II > Flashcards

Hepatitis Viruses II Flashcards

1
Q

Hepatitis D Virus

A
  • Hepatitis D Virus genus of the Deltaviridae family
  • ( - ) ss RNA circular
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2
Q

Hepatitis D Virus Structure and Replication

A
  • Single stranded RNA virus, circular (-) negative
  • Requires the presence of hepatitis B surface antigen (HBsAg) for its transmission and assembly but not transcription
  • Transcription method not understood
  • Transcription is independent of HBV
  • Replicates in the nucleus using host polymerase
  • HBsAg surrounds the RNA–protein complex of HDV
  • Found in people with acute or chronic hepatitis B virus infection
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3
Q

HDV Clinical Disease

A
  • Simultaneous delta and hepatitis B infection
  • Superinfection with chronic hepatitis B.
  • Permanent hepatitis common
  • Accelerate the pace of chronic HBV infection
  • HBV and HDV infection could lead to cirrhosis of liver
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4
Q

HDV Diagnosis

A

•Antibody to delta, PCR

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5
Q

HDV Treatment and Prevention

A

•The surface protein of HDV is HBsAg and any measures aimed at limiting the transmission of HBV will prevent HDV transmission

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6
Q

Hepatitis C Virus

A
  • Hepatitis C Virus genus of the Flaviviridae family
  • ( + ) ss RNA icosohedral enveleoped
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7
Q

HCV Structure

A
  • l Parenterally transmitted (PT)–non–A, non–B hepatitis virus
  • (+) Stranded linear RNA of 10 Kb
  • Core antigen encloses RNA
  • Envelope E1/E2 surrounds the core
  • Nonstructural genes encode HCV protease and polymerase activities
  • Inhibitors for HCV protease and polymerase available
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8
Q

HCV Replication

A
  • Replicates in the cytoplasm, multiple receptor
  • (+) RNA replicates via (–) RNA intermediate
  • (+) RNA is translated into a polyprotein and cleaved into mature proteins by proteases
  • Virus assembly in the cytoplasm
  • Genetic variability observed in the envelope of the virus
  • Eleven major genotypes with different geographic distribution and disease severity
  • Genotypes 1-3 are common, with genotype 1a predominating in North America
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9
Q

HCV Incubation

A
  • Incubation period averages 6 - 12 weeks
  • Acute phase is mild, asymptomatic in 75%
  • Results in chronic disease in more than 85% of patients
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10
Q

HCV Clinical Disease

A
  • Was associated with mainly with blood transfusions until blood screening for HCV was introduced
  • Sexually transmitted but to a lesser extent than hepatitis B
  • Needle sharing accounts for up to 40% of cases
  • Worldwide distribution
  • Slow disease progression (average 10 -18 years), chronicity tends to wax and wane
  • Could lead to cirrhosis of liver (10-20% with chronic infection) and hepatocellular carcinoma (1-5%).
  • Chronic hepatitis C is the leading cause of liver transplantation in the United States
  • Mechanism of oncogenicity unclear
  • Role of HCV core and non-structural proteins have been implicated
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11
Q

HCV Pathogenesis

A
  • Rate of HCV replication 1X1012 virions per day
  • 10% hepatocytes are infected
  • Some direct viral cytopathic effect, but hepatocytes are mainly killed by cytotoxic T cells (CTL) – Type IV hypersensitivity
  • Proinflammatory cytokines are release by innate immune cells, INF-alpha/beta initially controls viral infection
  • Th1 T cells lead to more necrosis and apoptosis
  • Chronic HCV infection promotes insulin resistance by increasing inflammatory response, TNF-alpha and IL-6 leading to progression of cirrhosis & HCC
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12
Q

HCV Diagnosis

A
  • Antibody detection by ELISA
  • Confirmation by PCR (RT-PCR)
  • Elevated liver enzyme alanine amino transferase (ALT)
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13
Q

HCV Treatment First Line

A
  • Interferon-a with ribavirin: first line of treatment, response better in patients with genotypes other than I and lower viral load.
  • Virus comes back after sometime
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14
Q

HCV Treatment - Protease Inhibitors

A
  • Telaprevir (Incivek), Boceprevir (Victrelis) and simeprivir (Olysio).
  • Develops resistance, works better if combined with interferon + ribavirin. The second generation of protease inhibitors include semeprevir, paritaprevir, and grazoprevir
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15
Q

HCV Treatment - Polymerase Inhibitors

A
  • The nucleotide HCV RNA polymerase inhibitor includes sofosbuvir (Sovaldi) that terminates the RNA synthesis of HCV.
  • The nonnucleoside HCV polymerase inhibitor includes dasabuvir that inhibits HCV RNA polymerase.
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16
Q

HCV Treatment - NS5A (phosphoprotein) inhibitors

A

•The inhibitors of HCV NS5A phosphoprotein, that is critical for HCV replication, includes daclatasvir, elbasvir, ledipasvir, ombitasvir, and velpatasvir.

17
Q

HCV Treatment - Combination Therapy

A

•Combination therapy that includes interferon-α and ribavirin, interferon and ribavirin plus a HCV protease inhibitor or a HCV polymerase inhibitor are used that works better for some genotypes than others.

18
Q

HCV Treatment - New Combination Therapy

A

•includes non-interferon combination in 7 combinations: 1) a fixed-dose combination of sofosbuvir (HCV polymerase inhibitor)— velpatasvir (NS5A inhibitor) plus ribavirin for genotype 1, 2, 3, 4, 5; 2) dasabuvir (nonnucleoside HCV polymerase inhibitor), ombitasvir (NS5A inhibitor), paritaprevir (HCV protease inhibitor) plus ritonavir (HIV protease inhibitor, increases levels of paritaprevir); and 5 more combinations

19
Q

Hepatitis E Virus

A
  • Hepatitis E Virus genus of the Hepeviridae family
  • ( + ) ss RNA icosohedral naked
  • spikes on surface
  • Most cases in India and in other countries with poor sanitation
  • Rarely identified in the United States
20
Q

HEV Structure and Replication

A
  • ET non–A, non–B hepatitis virus (enterically transmitted
  • RNA virus similar to calicivirus, ss (+) RNA
  • Spherical 27 to 34 mm particle
  • Unenveloped, spikes on surface
21
Q

HEV Clinical Disease

A
  • Transmitted through fecal–oral route
  • Causes acute disease like HAV
  • May fulminate especially in pregnant women
22
Q

HEV Diagnosis

A
  • Immunological assays
  • Presence of specific IgM l Detection of RNA by PCR
23
Q

HEV Prevention

A

•Not known if immune serum globulin prevents infection

24
Q

HEV Treatment

A

•No treatment is available

25
Q

Hepatitis G Virus or GBV-C

A
  • Hepatitis G Virus genus of the Flaviviridae family
  • ( + ) ss RNA icosohedral enveloped
26
Q

HGV Clinical Disease

A
  • Chronic infection in the absence clinical disease
  • Up to 5% of blood donors positive for HGV RNA
  • 10-20% of HCV infected patients have HGV
  • Clinical manifestations of acute hepatitis did not differ from those with coinfection of (HGV+HCV)
27
Q

HGV Risk Factors

A
  • Risk factors include; transfusion, IV drug users, and multiple sex partners
  • HGV prolongs the life of HIV infected patients
  • 35% of HIV patients are positive for HGV

I & I Part II (25 decks)

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