Hepatitis Serologic Markers
Rahul's Noteblog
Notes on Virology
Hepatitis Serologic Markers
Hepatitis Serologic Markers:
I've noticed a lot of people have a hard time memorizing the Hepatitis serologic markers and their association with disease status in a Hepatitis patient. In this article, I'll attempt to provide a simple way to remember and recall some basic Hepatitis serologic markers and their application in internal medicine.
First of all, I'd like you to carefully look at Figure 1 below:
Structure of a Hepatitis Virus:
All you have to do is memorize three letters: "S-E-C" for "surface," "envelope," and "core." Note that this may not be the correct structure of a Hepatitis virus, but may serve its purpose in helping us remember some important serologic markers.
Now, look at the diagram below:
Timeline of Hepatitis Serologic Markers:
This diagram displays the rising and falling Hepatitis serologic markes after months of exposure. Let us start from the beginning of Hepatitis infection.
Explanation:
1. The first serologic marker that shows up in a Hepatitis infection is HBsAg. According to Figure 1, HBsAg is the "outermost" portion of the Hepatitis virus and is detected first. In indicates a carrier state. Note that this is an antigen i.e., an antibody generator. However, the HBsAb will come later during the infection.
2. The second serologic marker that shows up in a Hepatitis infection is HBeAg. According to Figure 1, HBeAg is the "middle" portion of the Hepatitis virus and is detected second. It is an indicator of active viral replication and high transmissibility. Note that this is an antigen i.e., an antibody generator. However, the HBeAb will come later during the infection.
3. According to Figure 1, the third serologic marker in a Hepatitis infection should have been "HBcAg," however, for USMLE purposes we ignore this antigen. Instead we state that the third serologic marker is the antibody to HBcAg i.e., HBcAb. However, there are two antibodies to HBcAg: IgG and IgM. IgM indicates recent disease and IgG indicates chronic disease.
4. Now we have the antibody to HBeAg called HBeAb and this is an indicator of low transmissibility. This is our body's reaction to step 2 above. Note that HBeAg increases the risk for vertical transmission to baby in pregnant women.
5. Now comes the "window period." This is the time when the body is desperately generating antibodies to HBsAg. The only serologic markers positive during the window period are HBcAb and HBeAb.
6. The antibody to HBsAg is finally being produced and is called HBsAb. This means that the body is now immune to Hepatitis B infection.
Additional Notes:
The presence of HBsAb signifies immunity; the presence of HBsAb and HBcAb signifies past infection. Testing indicating a negative HBsAg with a positive IgM anti-HBc indicates that the infection is resolving.
Additional Readings:
Basic Virology
1. Immune defences against viruses
2. Viral Hepatitis
3. DNA viruses
4. Positive-sense RNA viruses
5. Human Immunodeficiency Virus
6. Negative sense RNA viruses
7. Double stranded RNA Viruses
8. Viruses associated with cancer
9. Generalized vs specialized transduction
10. Hepatitis serologic markers
11. Bacterial vs viral infections
12. Human Immunodeficiency Virus (HIV) Infections and AIDS
13. Steps When Patient is Newly Diagnosed with HIV
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