Ch 22 Flashcards
(188 cards)
1
Q
How many genotypes does HBV have?
A
HBV has 8 genotypes (A–H), based on genetic sequence variation.
2
Q
How much higher is the risk of liver cancer (HCC) in HBV carriers?
A
200 times higher than in non-carriers
3
Q
What is the risk of chronic infection in maternal-neonatal HBV transmission?
A
70–90% of newborns infected at birth develop chronic infection.
4
Q
What are the main routes of HBV transmission?
A
•Sexual
•Parenteral (via blood, e.g. needles)
•Perinatal (mother to baby at birth)
5
Q
How long can HBV survive outside the body and still cause infection?
A
At least 7 days
6
Q
Which non-human primate is susceptible to HBV?
A
Only chimpanzees, but they are no longer used in research due to ethical concerns
7
Q
What type of genome does HBV have?
A
A partially double-stranded circular DNA genome in an enveloped virion.
8
Q
How does HBV replicate?
A
It replicates through an RNA intermediate using a reverse transcriptase enzyme.
9
Q
What enzyme does HBV encode and carry?
A
Reverse transcriptase, which converts RNA back into DNA.
10
Q
What is the role of HBV viral proteins?
A
They are antigenic and clinically important for:
•Diagnosis
•Predicting disease severity
•Monitoring treatment
11
Q
Where does HBV primarily infect?
A
It has a strict tropism for the liver, but markers can be found in lymphoid tissues (spleen, lymph nodes).
12
Q
What is HBsAg, and what is special about its production?
A
HBsAg = surface antigen, produced in large amounts without DNA, and used in diagnostic tests.
13
Q
Can HBV DNA integrate into the host genome?
A
Yes, viral DNA can integrate, which may lead to chronic disease or liver cancer.
14
Q
What type of genome does HDV have?
A
Small, circular, single-stranded RNA genome (~1700 nucleotides).
15
Q
Why does the HDV genome form a rod-like shape?
A
Due to extensive internal base pairing within the RNA strand.
16
Q
What surrounds the HDV RNA genome?
A
The delta antigen protein.
17
Q
What does the HDV envelope contain?
A
HBsAg (Hepatitis B surface antigen), borrowed from HBV.
18
Q
Why does HDV depend on HBV?
A
Because HDV needs HBsAg from HBV to form its envelope and become infectious.
19
Q
What are the two forms of delta antigen?
A
Small (24 kDa) and Large (27 kDa).
20
Q
What is the function of the small delta antigen (24 kDa)?
A
It promotes viral replication.
21
Q
What is the function of the large delta antigen (27 kDa)?
A
It helps in viral assembly and interaction with HBsAg.
22
Q
Why does HDV need HBV to replicate?
A
Because HDV uses HBsAg from HBV to enter cells and form its envelope.
23
Q
What is the difference between co-infection and superinfection in HDV?
A
• Co-infection: HBV and HDV infect the person at the same time.
• Superinfection: HDV infects someone who already has chronic HBV.
24
Q
Which is more severe: co-infection or superinfection?
A
Superinfection is more severe and can lead to worse liver damage.
25
Does HDV have a direct cytopathic effect?
Yes, HDV directly damages liver cells
26
How does HDV affect HBV-related liver damage?
HDV exacerbates (worsens) the liver damage caused by HBV
27
Can HDV cause chronic infection?
Yes, especially in people who are chronic HBV carriers.
28
What protects a person from HDV infection?
Immunity against HBsAg, either from HBV vaccination or past HBV infection.
29
What does HDV require to infect and replicate?
Co-infection with HBV.
30
What percentage of HBV carriers are affected by HDV?
About 5% of the 300 million HBV carriers.
31
In which regions is HDV considered endemic?
Southern Italy, Amazon Basin, Africa, and the Middle East.
32
Where have HDV epidemics occurred outside endemic regions?
In North America and Western Europe, mainly among intravenous drug users.
33
Who are considered high-risk groups for HDV infection?
• IV drug users
• Hemophiliacs
• Recipients of blood products
34
How does HDV affect HBV disease severity?
It increases the severity, making complications more likely.
35
What serious condition is more likely with HDV co-infection?
Fulminant hepatitis.
36
What are the symptoms of fulminant hepatitis?
•Hepatic encephalopathy
•Jaundice
•Massive hepatic necrosis
37
What is the fatality rate for fulminant hepatitis caused by HDV?
About 80%.
38
What are the lab methods to diagnose HDV infection?
• RT-PCR to detect HDV RNA
• Detect delta antigen (in acute phase)
• Detect anti-HDV antibodies using ELISA or radioimmunoassay
39
What special step is needed to detect delta antigen in serum?
The serum sample should be detergent-treated
40
What receptor does HBV use to attach to hepatocytes?
HBV uses the huNTCP receptor (Human sodium taurocholate co-transporting polypeptide)
41
What happens after HBV enters the hepatocyte?
The virus undergoes uncoating and releases its DNA.
42
What is the form of HBV DNA in the nucleus called?
cccDNA – covalently closed circular DNA.
43
Which enzyme transcribes HBV cccDNA into mRNAs?
Host RNA polymerase II.
44
Where are the HBV viral proteins synthesized?
In the cytoplasm, through translation of viral mRNAs.
45
What is reverse transcribed into DNA inside the capsid?
pgRNA (pregenomic RNA) is reverse transcribed into DNA.
46
What happens after new HBV virions are assembled?
They are released from the cell to infect others.
47
How does HBV maintain chronic infection inside the cell?
Some capsids are recycled back to the nucleus to maintain cccDNA.
48
Does HBV cause direct damage to liver cells?
No, direct cytopathic effect is minimal. Most damage is caused by the immune response.
49
What is the main cause of liver pathology in HBV infection?
Immune-mediated damage, especially by cytotoxic T lymphocytes (CTLs).
50
How do CTLs (CD8+ T cells) contribute to HBV pathogenesis?
They kill infected hepatocytes, leading to liver inflammation and damage.
51
What determines the severity of HBV disease?
The strength of the host’s immune response
52
What kind of immune response leads to chronic HBV infection?
A weak or tolerogenic immune response.
53
What are the main components of innate immunity against HBV?
Type I interferons (IFNs) and natural killer (NK) cells.
54
How do CD8+ T cells help control HBV infection?
By killing virus-infected hepatocytes.
55
What is the role of CD4+ T cells in HBV immunity?
They support B cell activation and antibody production
56
What do B cells do in HBV infection?
Produce neutralizing antibodies against HBsAg (Hepatitis B surface antigen).
57
What is required to resolve acute HBV infection?
A strong CD8+ T cell and Th1 (CD4+ T cell) response.
58
How do infected hepatocytes present HBV antigens?
Via MHC class I, displaying HBV peptides to cytotoxic T cells.
59
How do cytotoxic T cells (CTLs) cause liver damage in HBV infection?
Through apoptosis of infected cells and cytokine-induced damage.
60
What are the stages of liver damage progression in chronic HBV?
Chronic inflammation → Fibrosis → Cirrhosis → Hepatocellular carcinoma (HCC).
61
What increases the risk of disease progression in HBV?
High viral load and persistent inflammation.
62
Is HBV a risk factor for hepatocellular carcinoma (HCC)?
Yes, HBV is a major risk factor for HCC.
63
How does chronic HBV infection contribute to HCC development?
Through chronic inflammation and continuous cell regeneration.
64
How does HBV DNA integration affect the host genome?
It can disrupt normal genes and promote oncogenesis (cancer formation).
65
What is the role of HBx protein in HCC?
HBx has oncogenic effects, promoting cancer development.
66
Can HBV-related HCC occur without cirrhosis?
Yes, HBV can cause HCC even without cirrhosis.
67
How many HBV cases were reported in the West Bank (Palestine, 2023)?
22 cases reported; 339 carriers identified.
68
How many HBV carriers were there in Gaza Strip (2023)?
63 carriers.
69
What is the most common route of HBV transmission in high-prevalence areas?
Perinatal transmission (from mother to baby at birth).
70
What are the main transmission routes of HBV?
• Perinatal
• Sexual contact
• Blood and body fluid exposure
• Horizontal transmission in children
71
How can HBV be transmitted through blood?
Via IV drug use, blood transfusions, or contact with infected body fluids.
72
Who are at high risk for HBV infection?
• Infants of HBV-positive mothers
• Healthcare workers
• People with multiple sexual partners
• IV drug users
73
What are the key methods for preventing HBV transmission?
• Universal vaccination
• Screening blood products
• Safe sex and injection practices
• Post-exposure prophylaxis (vaccine + HBIG)
74
What is post-exposure prophylaxis for HBV?
HBV vaccine + HBIG, given after exposure to prevent infection.
75
What type of vaccine is used for HBV?
A recombinant vaccine made from HBsAg (Hepatitis B surface antigen).
76
What is the HBV vaccine schedule?
3 doses at months 0, 1, and 6.
77
How effective is the HBV vaccine?
About 95% protective efficacy.
78
What does the HBV vaccine stimulate the production of?
Anti-HBs antibodies, which provide immunity
79
What does WHO recommend for HBV prevention in infants?
Universal infant vaccination.
80
Is acute hepatitis B usually symptomatic?
No, it’s often asymptomatic, but may cause jaundice, fatigue, and nausea.
81
What is fulminant hepatitis?
A rare and severe form of hepatitis that causes rapid liver failure.
82
When is hepatitis B considered chronic?
When HBsAg persists for more than 6 months.
83
What can chronic hepatitis B progress to?
t may lead to cirrhosis and hepatocellular carcinoma (HCC).
84
What is cirrhosis?
Fibrosis (scarring) of the liver that impairs its function.
85
What is the major long-term complication of chronic HBV?
Hepatocellular carcinoma (HCC) – primary liver cancer.
86
What is Polyarteritis Nodosa (PAN) and how is it related to HBV?
PAN is a vasculitis of medium-sized arteries linked to immune complex deposition in HBV.
87
What kidney condition can HBV cause through immune complexes?
Membranous glomerulonephritis, due to immune complex deposition in glomeruli.
88
What is essential mixed cryoglobulinemia?
A condition involving cold-precipitating antibodies that cause vasculitis, linked to HBV.
89
What is aplastic anemia and how is it related to HBV?
A condition where the bone marrow fails to produce blood cells, possibly due to an autoimmune reaction triggered by HBV.
90
What is the common mechanism behind these HBV-related complications?
Immune complex deposition or autoimmune reactions.
91
What does Anti-HBs indicate?
Recovery or immunity due to vaccination.
92
What does Anti-HBc IgM suggest?
Acute or recent HBV infection.
93
What does total Anti-HBc (IgG + IgM) indicate?
Past or current infection with HBV.
94
What does HBeAg indicate?
Active viral replication and high infectivity
95
What does Anti-HBe indicate?
Lower infectivity and seroconversion.
96
What is HBV DNA (PCR) testing used for?
To measure viral load and guide treatment decisions.
97
What does the presence of HBsAg indicate?
Current HBV infection (either acute or chronic).
98
What is unique about the window period in HBV infection?
HBsAg and Anti-HBs are both negative; only Anti-HBc IgM is positive.
99
What serological markers define the early acute phase of HBV?
HBsAg +, Anti-HBc IgM +, HBV DNA +++, ALT ↑
100
What indicates recovery from HBV?
Anti-HBs +, Anti-HBc IgG +, HBsAg -, ALT normal
101
What are the features of immune-tolerant chronic HBV?
HBsAg +, HBeAg +, HBV DNA +++, ALT normal or slightly high
102
How does immune-active chronic HBV (HBeAg +) present?
HBsAg +, HBeAg +, HBV DNA +++, ALT increased
103
What defines immune-active HBV (HBeAg -)?
HBsAg +, Anti-HBe +, HBV DNA ++, ALT increased
104
What are the lab results in inactive chronic HBV?
HBsAg +, Anti-HBe +, low/undetectable HBV DNA, ALT normal
105
What is occult HBV infection?
HBsAg -, Anti-HBc +/- , HBV DNA low (in liver), ALT norma
106
What are serology results in a vaccinated person?
Anti-HBs + only; all other markers negative
107
A 25-year-old male has the following serologic profile: HBsAg (+), HBeAg (+), Anti-HBc IgM (+), Anti-HBs (-), ALT elevated. What is the most likely stage of infection?
A. Recovery
B. Immune-tolerant chronic HBV
C. Acute HBV infection
D. Vaccinated
C
108
A 23-year-old male presents with fatigue, nausea, and mild jaundice. Labs show:
• HBsAg: +
• Anti-HBc IgM: +
• HBeAg: +
• Anti-HBs: -
• ALT: High
What is the most likely diagnosis?
A. Vaccinated
B. Acute HBV infection
C. Recovery phase
D. Inactive chronic HBV
B
109
A patient recently exposed to HBV shows the following serology:
• HBsAg: -
• Anti-HBs: -
• Anti-HBc IgM: +
• ALT: Elevated
What is the best explanation?
A. Immune-tolerant phase
B. Acute infection
C. Window period
D. Vaccinated
C
110
A 30-year-old nurse underwent routine testing. Results:
• HBsAg: -
• Anti-HBs: +
• Anti-HBc: -
What does this indicate?
A. Past resolved infection
B. Vaccinated
C. Chronic infection
D. Acute infection
B
111
A 50-year-old man is known to have HBV. His latest labs:
• HBsAg: +
• HBeAg: -
• Anti-HBe: +
• Anti-HBc IgG: +
• ALT: Normal
• HBV DNA: Low
Diagnosis?
A. Immune-tolerant chronic HBV
B. Immune-active chronic HBV
C. Inactive chronic carrier
D. Acute HBV
C
112
A patient had acute hepatitis B 6 months ago. Now labs show:
• HBsAg: -
• Anti-HBs: +
• Anti-HBc IgG: +
• Anti-HBc IgM: -
What is the interpretation?
A. Vaccinated
B. Recovery from natural infection
C. Chronic infection
D. Acute infection
B
113
A 12-year-old boy born to an HBV-positive mother is screened:
• HBsAg: +
• HBeAg: +
• Anti-HBc IgG: +
• Anti-HBc IgM: -
• ALT: Normal
• HBV DNA: Very high
What is the most likely diagnosis?
A. Acute HBV
B. Immune-active chronic HBV
C. Immune-tolerant chronic HBV
D. Inactive carrier
C
114
A 40-year-old man with chronic HBV complains of fatigue. Labs:
• HBsAg: +
• HBeAg: +
• Anti-HBe: -
• Anti-HBc IgG: +
• ALT: High
• HBV DNA: High
Diagnosis?
A. Inactive chronic HBV
B. Immune-active chronic HBV (HBeAg +ve)
C. Recovery
D. Vaccinated
B
115
A 45-year-old male has long-standing HBV. Latest results:
• HBsAg: +
• HBeAg: -
• Anti-HBe: +
• Anti-HBc IgG: +
• ALT: High
• HBV DNA: Moderate
What is the diagnosis?
A. Inactive carrier
B. Window period
C. Immune-active chronic HBV (HBeAg -ve)
D. Fulminant hepatitis
C
116
A blood donor tested negative for HBsAg, but further testing showed:
• Anti-HBc: +
• Anti-HBs: +/-
• HBV DNA: Detectable only in liver
Interpretation?
A. Vaccinated
B. Acute infection
C. Occult HBV infection
D. Window period
C
117
A 28-year-old woman presents with sudden onset jaundice, confusion, and coagulopathy. Her serology:
• HBsAg: +
• Anti-HBc IgM: +
• ALT: Very high
Diagnosis?
A. Chronic HBV
B. Inactive carrier
C. Fulminant hepatitis B
D. Vaccinated
C
118
What is the treatment for acute Hepatitis B?
Supportive treatment only (rest, fluids, nutrition).
119
When is Hepatitis B considered chronic?
When the infection lasts more than 6 months.
120
What are the first-line drugs for chronic Hepatitis B?
Tenofovir and Entecavir.
121
What drug class do Tenofovir and Entecavir belong to?
Nucleotide analogue reverse transcriptase inhibitors (NtRTIs).
122
How do NtRTIs work?
They mimic natural nucleotides to block viral DNA replication.
123
What type of genome does Parvovirus B19 have?
Single-stranded linear DNA (~5500 bases)
124
Is Parvovirus B19 enveloped or nonenveloped?
Nonenveloped
125
What is the shape of the Parvovirus B19 capsid?
Icosahedral
126
How does Parvovirus B19 replicate?
It depends on the host cell machinery or a helper virus (like adenovirus)
127
What proteins are encoded by Parvovirus B19?
3 structural proteins and 2 nonstructural proteins
128
Can viremia persist after respiratory symptoms in Parvovirus B19 infection?
Yes
129
What are the main diseases caused by Parvovirus B19 in humans?
• Fifth disease (erythema infectiosum)
• Aplastic crisis
• Arthritis
• Fetal hydrops (in pregnant women)
• Respiratory tract illness
130
Who is mainly affected by Human Bocavirus?
Children (causes acute respiratory disease)
131
Are Adeno-Associated Viruses (AAVs) pathogenic?
No, they are nonpathogenic and used in gene therapy.
132
Which Parvovirus can cause fetal hydrops during pregnancy?
Parvovirus B19
133
What is Fifth disease and which virus causes it?
A mild rash illness in children caused by Parvovirus B19
134
Which Parvovirus is useful in gene therapy and not known to cause disease?
AAVs (Dependovirus)
135
What disease does Feline panleukopenia virus cause in cats?
Enteritis, leucopenia, cerebellar ataxia
136
What are the diseases caused by Canine parvovirus in dogs and foxes?
Enteritis and myocarditis
137
What does Porcine parvovirus cause in pigs?
Reproductive failure
138
What disease does Aleutian disease virus cause in mink?
Pneumonitis
139
What does Mink enteritis virus cause?
Enteritis
140
What is the host and disease for Simian parvovirus?
Host: Monkey
Disease: Anaemia
141
Are Human bocavirus and Human parvo virus 4 diseases known?
No, their diseases are currently unknown.
142
What type of cells does Parvovirus B19 infect?
Mitotically active cells, especially erythroid precursor cells.
143
Does Parvovirus B19 encode its own polymerase or growth stimulators?
No, it relies on the host cell’s machinery.
144
What receptor does B19 virus use to enter cells?
P antigen (globoside) on red cell precursors.
145
Where does Parvovirus B19 uncoat and replicate?
In the nucleus of the host cell.
146
How is ssDNA converted to dsDNA in B19 replication?
Host DNA polymerase converts it inside the nucleus.
147
What role do inverted terminal repeats play in B19 replication?
They help form primer structures for DNA synthesis.
148
How are new B19 virions released from the host cell?
By cell lysis (the host cell bursts open).
149
How does Parvovirus B19 damage erythroid cells?
It directly kills erythroid precursor cells.
150
What causes the rash and joint pain in B19 infection?
Immune complex formation (antibody–virus complexes).
151
What are the two phases of B19 disease?
• Febrile phase: High viremia, contagious
• Symptomatic phase: Immune-mediated symptoms (rash, arthralgia)
152
Which cells does Human Bocavirus infect?
Respiratory epithelium.
153
What serious condition can Bocavirus cause in children?
Bronchiolitis (inflammation of small airways).
154
Can viremia from Bocavirus continue after respiratory symptoms disappear?
Yes, viremia may persist.
155
What is a key symptom of erythema infectiosum caused by B19?
Slapped cheek rash that spreads to the limbs.
156
What symptom does Parvovirus B19 commonly cause in adults?
Polyarthritis (joint pain and swelling).
157
How does B19 affect healthy individuals?
Often asymptomatic or causes mild illness.
158
What is the risk of B19 infection in immunocompromised individuals?
Chronic infection due to inability to clear the virus.
159
What complication can B19 cause in patients with chronic hemolytic anemia?
Aplastic crisis (sudden halt in red cell production).
160
What is the danger of B19 infection during pregnancy?
Risk of hydrops fetalis in seronegative pregnant women.
161
What age group is mainly affected by Human Bocavirus?
Children under 2 years old.
162
What are common symptoms of Bocavirus infection?
Bronchiolitis and wheezing.
163
Can Bocavirus viremia continue after symptoms resolve?
Yes, prolonged viremia is possible.
164
Is Bocavirus ever fatal?
Rarely, but it can be fatal in severe cases.
165
What percentage of people have antibodies to B19 virus by age 40?
About 65% (seroprevalence by age 40).
166
What age group is most commonly affected by Parvovirus B19?
Children aged 4–15 years
167
How is Parvovirus B19 transmitted?
Through respiratory droplets and oral secretions
168
When does B19 infection most commonly occur?
In late winter and spring.
169
Is Human Bocavirus found worldwide?
Yes, it has a global distribution.
170
Which age group is mainly affected by Human Bocavirus?
Children under 2 years old.
171
How is Bocavirus transmitted?
Via respiratory secretions and stool.
172
Is there a specific antiviral treatment for Parvovirus B19?
No, treatment is supportive only.
173
What can be used to relieve itching from B19 rash?
Topical anesthetics or antihistamines.
174
What is used in chronic B19 infection in immunocompromised patients?
Intravenous Immunoglobulin (IVIG).
175
What treatment might be needed during an aplastic crisis caused by B19?
Packed red blood cell (RBC) transfusion.
176
Are vaccines available for parvovirus in animals?
Yes, vaccines are available for dogs and cats.
177
Is there a human vaccine for Parvovirus B19?
Not yet, but it is currently in clinical trials.
178
What is the role of AAVs in medicine?
Used in gene therapy due to their safety and nonpathogenic nature.
179
What does IgM – / IgG + indicate in B19 testing?
Past infection; patient is immune.
180
What does IgM + / IgG – indicate?
Recent infection; confirm with PCR for B19 DNA.
181
What does IgM + / IgG + indicate?
Recent infection; may require PCR on amniotic fluid.
182
What does IgM – / IgG – indicate?
No past or current infection; confirm with PCR of maternal serum.
183
What does a positive PCR result mean in maternal serum?
Recent infection; possible transmission to fetus
184
What does a negative PCR result mean?
No current infection; mother is susceptible and should be monitored.
185
A 30-year-old pregnant woman is tested for B19 IgM/IgG.
Results: IgM negative / IgG positive
Interpretation:
• Past infection
• Immune to B19 virus
• No further action needed
186
A pregnant woman at 20 weeks’ gestation shows:
IgM positive / IgG negative
Interpretation:
• Recent infection
• Perform PCR on maternal serum
• If PCR positive → risk of fetal infection
• Monitor fetus and consider amniotic fluid PCR
187
A pregnant woman has the following results:
IgM positive / IgG positive
Interpretation:
• Recent infection with beginning immune response
• Confirm with PCR on serum or amniotic fluid
• If PCR positive → monitor fetus for hydrops fetalis
188
A pregnant woman has the results:
IgM negative / IgG negative
Interpretation:
• No evidence of past or current infection
• Perform PCR on maternal serum to confirm
• If PCR negative → she is susceptible, monitor during pregnancy
