Flashcards in LMP301 Lecture 16: Viral Hepatitis Deck (111)
Causes of hepatitis
inflammation of the liver
drugs that may cause hepatitis
- tylenol/asprin overdose
toxins that may cause hepatitis
bacteria that may cause hepatitis
- thyphoid fever
viruses that may cause hepatitis
- hepatitis A, B, C, D, E, G
parasites that may cause hepatitis
clinical symptoms of viral hepatitis
- enlarged liver
- elevated liver enzymes
- change colour of urine/feces
- accumulation of biliburin (jaundice)
on a virus particle, what can be used to identify the strain?
- ssDNA or RNA
- surface proteins (HBsAg)
define: antigen (Ag)
a substance (protein) that prompts the generation of antibodies -> immune response
define: antibody (Ab/IgG/IgM)
proteins produced by B-cells which play an immunological role; identify & neutralizes foreign particles through antigens
Which antibody is first released when there is an immune response? Which is released after?
IgM, then IgG
primary immune response
__ are produced during the primary immune response
The virus particle is surrounded by...
The genetic material of virus is in the form of...
DNA or RNA (single or double stranded)
what is directly inside the capsule coat?
Viral nucleocapsid (HBcAg)
particles associated with nucleocapsid
Where are HBeAg found?
inside the viral capsid (HBcAg)
When does the production change from IgM to IgG?
after mature B cells are formed
What is it called when IgG production begins and IgM production stops?
a stable change in the B-cell's genome, and is transmitted to all progeny cells
Lifecycle of a virus
1. enters hepatocyte (capsule coat removed), viral DNA moves to nucleus of host
2. viral dsDNA -> cccDNA -> template for viral mRNA
3. viral mRNA transcription & assembly of new viral particles
4. viral proteins assemble around DNA core
5. new viral particles released from outer membrane of the host
dsDNA -[?]-> cccDNA
___ can persist in the hepatocyte during chronic infection
cccDNA is genetic material of...
Steps of viral reproduction
2. Repair (formation of cccDNA)
How does release of viral particles determine host cell health?
If a little bit of the particle is released at a time, host lives
if all released, host dies
If the host cell dies, what happens to the viral production cycle?
Describe the Hep A virus
- ssRNA (single protein core)
- no surface proteins to identify
how is Hep A virus transmitted?
- person-to-person contact
- contaminated water
- poor hygiene & sanitation
Who is at high risk for Hep A?
- children in daycare
- travelers to places where sanitation is bad
onset of symptoms for Hep A
- very abrupt
- lasts 1 ~ 8 weeks
what is a common clinical symptom of Hep A? How many adults develop this symptom?
What is responsible for causing Hep A?
where does HAV replicate?
how does HAV leave the body?
when is HAV most infectious (found in stool)?
first 2 weeks of contracting disease, a lot of HAV will be found in the stool
When does [HAV] decline in the stool?
after jaundice appears
what happens to those people who have Hep A?
will recover, and develop immunity to HAV
what is a marker used for diagnosing/confirming recent/acute HAV infection?
anti-HAV IgM + ALT (liver enzyme)
what is a marker that indicates immunity to HAV?
anti-HAV IgG, and the absence of anti-HAV IgM in serum
clinical symptoms of Hep A appears about...
2 weeks after infection, and lasts until week 8 (duration: 6 weeks)
What anti-HAV IgG a marker off?
past or present infection; cannot make a definitive diagnosis of a recent infection
genome of HBV
double stranded circular DNA
What are the 2 antigens found on HBV?
- Hep B surface antigen (HBsAg)
- Hep B core antigen (HBcAg)
What is the structure that holds viral DNA?
central core nucleocapsid
What is the main structural difference between HAV and HBV?
HBV has a coat over the capsid that contains surface proteins
transmission of Hep B
exchange of body fluids
individuals at risk for Hep B
- injection drug users
- unsafe sex
- occupation working with blood
- institutionalized populations (prisoners)
incubation period for Hep B
60 - 90 days (2-3 months)
Onset of Hep B is very...
Less / More people develop jaundice when infected with HBV compared to HAV
less (only 30-50%)
What happens to individuals infected with HBV?
recover within six months and develop immunity
2-10% of infected individuals with Hep B will progress to...
15-50% of people with chronic Hep B...
die prematurely as a result of chronic liver disease
Markers of Hep B
- anti-HBc (IgM)
- anti-HBe (IgG)
- anti-HBs (IgG)
Hep B surface antigen
Hep B envelope antigen
What can be used to identify the strain of Hep B?
type of HBsAg and HBeAg that can be found in serum
IgM antibody to the core antigen
antibody to HBe antigen
antibody to HBs antigen
What can be used to identify the stage of hepatitis infection?
see which antibody is secreted by the body (IgM or IgG)
What is used to follow patient progress throughout hepatitis infection?
serial testing: follow patient's progress using markers (HBsAg, HBeAg, anti-HBe, anti-HBs)
What markers can be seen for acute hepatitis?
- HBsAg = there are surface antigens
- HBeAg = there are envelop antigens
- anti-HBc (IgM) = there is a core
(the viral parts, mostly)
duration of an acute Hep B infection
2 weeks - 3 months
what markers appear during early recovery and recovery phase of Hep B?
anti-HBs & anti-HBe
duration of early recovery period for Hep B
duration of recovery for Hep B
6-12 months / years
what is the last marker to appear for Hep B?
What does the presence of anti-HBs and anti-HBe indicate?
- Hep B is resolving (leaves acute stage)
- establishment of immunity
individual is considered chronically infected if...
HBsAg is present for more than six months
what markers can be seen for chronic hep B infection?
- HBsAg and HBeAg are elevated even at later stage
- antibodies to those viral particles are also constantly present
Hep B: indicator of disease resolution
Hep B: indicator of recovery & immunity
Hep B: indicator of acute infection (unique to this category)
genomic material of HCV
ssRNA encased by nucleocapsid (core)
difference between envelope of HBV and HCV
HCV has an envelope proteins, but they can't be used to identify the strain
HCV is encased by...
size of HCV
< 50 nm
transmission of HCV
individuals at risk for Hep C
- injection drug users
- occupational hazard
- transfusions before 1992
- institutionalized populations (prisoners)
60-70% of people with Hep C have what symptom?
20-30% of people with acute Hep C have what symptom?
___% of Hep C patients become chronically infected
10-20% of people with chronic Hep C develop _____
1-5% of people with chronic Hep C develop _____
hepatocellular carcinoma occurs over...
20-30 years (latent infection)
HCV is a leading cause of....
HCV reacts differently depending on...
what other "factors" you have
- alcohol use
duration of incubation for HCV
avg: 6-7 weeks
when do people infected with HCV develop symptoms?
development of antibodies in response to disease states
how long does it take before seroconversion occurs for Hep C?
What individuals are considered infectious for Hep C?
* positive for HCV antibody
liver enzymes could still be normal
why might there not be an elevation in liver enzymes for those with Hep C?
slow infection cycle allows liver to slowly adjust to the increasing strain
how is HCV diagnosed?
1. detecting antibodies specific to HCV (anti-HCV)
2. ruling out HAV or HBV
symptoms of Hep C appears during...
week 1 - week 5 of infection period
downside of using anti-HCV as marker for diagnosis
- may not appear if tested early
- can take >2 months to become positive
- does not distinguish between acute & chronic
- can't tell when they got the disease
what can be found at a constant level for those infected with HCV?
what liver enzyme is abnormal in Hep C individuals, and what is the serologic pattern like?
- more abundant than normal (peak about week 2-3)
- decreases and goes fluctuates, slightly above normal range later on
serologic pattern for anti-HCV
increase as duration of Hep C increases (exponential)
HCV RNA measure...
level of circulating virus = "viral load"
high viral load means that...
the virus is replicating a lot
Why is HCV RNA testing used?
- detect HCV before anti-HCV may be formed
- access viral load before and after treatment
- detect HCV infection in cases with ambiguous serology (blood test)
which viral hepatitis has abrupt onset
which hep virus has the shortest incubation time?
which hep virus will most likely cause a chronic infection?