One of the common liver diseases found worldwide is Hepatitis B caused by Hepatitis B virus. It can cause liver cirrhosis (scarring of the liver) and hepatocellular carcinoma (HCC). For some people, it is a short-term illness and for others it can cause chronic conditions and put their lives at high risk. This Hepatitis B can be prevented by vaccination and many other drug therapies. And also, by taking proper safety measures can prevent the spreading of virus.
Transmission
Disease can be transmitted by the following ways,
- Mother to child
- Unprotected sex
- Misuse of contaminated needles
- Exchange of infected bodily fluids such as blood, plasma, menstrual, vaginal and seminal fluid
Symptoms
Some people do not show any symptoms in both acute and chronic conditions. In chronic conditions, their liver is being silently destroyed and they also spread the disease to others without knowledge. However, some people show symptoms such as,
- Yellowing of eyes and skin
- Extreme fatigue
- Dark urine
- Abdominal Pain
- Fever
- Loss of appetite
- Vomiting and Nausea
About Hepatitis B Virus (HBV)
Hepatitis B is a small partially double-stranded DNA virus (3.2kb in size) which infects hepatocytes present in the liver. It consists of an outer lipid envelope and an icosahedral nucleocapsid core, which is made up of protein. Hepatitis B virus exists in 3 forms such as spherical (most common form), tubular, and Dane particle (complete form, rare).
- They have an outer envelope, made up of the HBsAg (Hepatitis B Surface Antigen/Australia Antigen).
- HBcAg (Hepatitis B Core Antigen) is present in the inner core.
- HBeAg (Hepatitis B precore Antigen) is present in between the core and outer envelope. This is secreted and hence present in blood.
Life Cycle
The complex life cycle includes the following steps,
- Attachment of HBV to the hepatic cell
- HBV enters the hepatic cell via phagocytosis
- Fusion of viral envelope and hepatic cellular membrane
- Releasing of viral capsid into the cytoplasm
- Viral capsid moves to liver cell nucleus and viral genome imports into nucleus (nuclear import)
- The relaxed circular DNA (rcDNA) converts to covalently closed circular DNA (cccDNA)
- Transcription of cccDNA to pre-genomic RNA
- Translation of RNA to HBV antigens (inside the cytoplasm)
- HBeAg releases into blood
- HBcAg performs encapsidation of HBV polymerase and pre-genomic RNA
- Pre-genomic RNA converts to DNA (DNA synthesis)
- Encapsidated nucleocapsid again repeats the steps from nuclear import
- HBsAg assembles to form viral envelope
- Viral envelope wraps up the capsid (assembly)
- Release of virus
Treatment of Hepatitis B
People diagnosed with chronic hepatitis B infection need treatment to prevent the progression of liver diseases such as cirrhosis and HCC. This disease can not be completely cured. Treatment can prevent the transmission of disease to others.
1. Antiviral drugs - Adefovir, Entecavir, Tenofovir, lamivudine and Telbuvidine
2. Interferon alpha injections
3. Liver Transplantation - If the liver is completely damaged, liver transplantation is the option
4. Everyone should get a hepatitis B vaccine to prevent the disease
Prevention and Control
- Vaccination
- Avoid sharing of needles to take drugs
- Use condom for sex
- Don't use infected person's belongings
- Verify the safety of the instruments used for tattooing and body piercing
- If you are a healthcare worker, then follow all safety precautions while handling samples
References
- Hepatitis B - Diagnosis and treatment - Mayo Clinic. (2020, September 4). Mayoclinic. https://www.mayoclinic.org/diseases-conditions/hepatitis-b/diagnosis-treatment/drc. 20366821#:%7E:text=Treatment%20for%20chronic%20hepatitis%20B%20may%20include%3A,ability%20to%20damage%20your%20liver.
- Schädler, S., & Hildt, E. (2009). HBV life cycle: entry and morphogenesis. Viruses, 1(2), 185–209. https://doi.org/10.3390/v1020185.
- What is Hepatitis B. (n.d.). Hepatitis B Foundation. https://www.hepb.org/what-is-hepatitis-b/what-is-hepb/.
