Hepadnaviridae (hepa =liver, dna= deoxyribonucleic acid) GROUP VII
As the name indicates, Hepadnaviridae are a family of viruses that cause infections to the liver of human and animals and all cause hepatitis in their known host. Hepatitis is an inflammation of the liver. However, not all type of hepatitis is caused by Hepadnavirus family as it can be caused by other viruses or non-infectious agent such as alcohol.

Family of hepadnaviridae:
Genus: Orthohepadnavirus consist of virus such as:
· Hepatitis B (HBV)
· Ground squirrel Hepatitis virus
· Woodchuck hepatitis virus
Genus: Avihepadnavirus consist of virus such as:
· Duck Hepatitis B
· Heron Hepatitis B

Viral genome of hepadnaviridae (enveloped DNA virus)

The core contains:

• Circular, partially dsDNA
• DNA polymerase
• an antigen (HBcAg)
• contain overlapping open reading frames.
• since it is a group VII virus, replication involves an RNA intermediate.

Pathogenesis

• Causes persistent infection, can be chronic or acute.
• Acute or chronic depends on age of infection
• About 90% of adults infected with HBV recover from it completely& become immune to it.
• Other 10% are those who become chronic carriers.
• Babies given birth by infected mother have a high risk of becoming a chronic carrier.
  Interesting fact: do you know that hepatitis B virus is 50 to 100 more time more infectious than HIV.

Symptoms of acute Hepatitis B

• Can last for several weeks
• Yellowing of skin & eyes (jaundice)
• Extreme fatigue
• Nausea, vomiting and abdominal pain

Chronic hepatitis B
As I mention before, chronic Hepatitis B virus depends upon the age at which the person is infected.

• young children who are infected, are most likely to develop chronic infection.
• A chronic carrier has no symptoms and no abnormalities on laboratory test however they are still potentially infectious.
• around 90% of infants infected during the first year of life develop chronic infection.
• about 25% of chronically infected adult who are infected during childhood, die from HBV-related liver cancer or cirrhosis.

For more information, you can watch this Hepatitis B virus video!

Detection, identification and diagnosis of virus
BASIC IMMUNOLOGY
Antigens are any foreign particle or molecule not recognised by the body and it causes an immune response. An antigen can be harmless such as grass pollen or harmful such as influenza virus. Antigen can be virus, bacteria, toxins, foreign proteins, etc. Disease causing antigens are called pathogens. The immune system is design for protecting against disease by identifying and killing the pathogens and tumour cells. Antibodies also known as immunoglobulin (Ig) are gamma globulin proteins that are found in blood or other bodily fluids and are used by the immune system to identify and neutralize foreign particles.

By Serological /Immunological methods
· Haemagglutination assay (HA)
· Haemagglutination inhibition (HI)
· Virus neutralisation
· Complement fixation

This week, to get the ball rolling, I am going to be the first to blog about virus.

And my topic for this week is CONTACT LENSES!

Talking about contact lenses, have u ever wonder how much virus is there in YOUR lenses IF you did not take care of it every day?


As you know, you are to take care of your lenses EVERY SINGLE DAY by pouring the solution to soak your lenses for over a night to kill any bacteria and or viruses. But do you know how much viruses and bacteria do your contact lenses bred if you just slack for a day?

Over there at University of Alabama at Birmingham, USA, Optometrists advise that

Wearing contacts may worsen your eye infection when you catch a virus that could lead to your tear production being altered.

As your eyes intends to get dry when your tear production changes, wearing of contact lenses would worsen the condition. And symptoms of eye infection such as pink eye, conjunctivitis would occur. And your cornea would swell.

Therefore, when you are sick, it is best to wear glasses.
If it is a must, try wearing daily lenses or clean them thoroughly as by not cleaning them thoroughly, you will still be as risk of getting eye infection during that period. And while in that period wearing contact lenses, it is advisable to take out your contact lenses to let your eyes rest for a certain period.


Below are three videos, telling you how to clean contact lenses correctly, a news report on Parasites that Infects Contact Lens Wearers and lastly, a video from the AOA(American Optometric Association), a recognised association sharing some Contact Lens Hygiene Tips.


Video teaching you how to clean contact lenses correctly



Video on how parasites will eventually infects Contact Lens Wearers



Video sharing some Contact Lens Hygiene Tips.


Thanks! signing off,
Yanling.