Which one of the following influenza A virus subtypes caused severe avian flu and was responsible for disease outbreak in the year 1997 in Hong Kong?
H5N1
Influenza A Virus Subtypes Explained
Influenza A viruses are classified into subtypes based on two surface proteins: hemagglutinin (H) and neuraminidase (N). There are 18 known H subtypes and 11 known N subtypes. Different combinations of H and N proteins result in different subtypes, for example, H1N1, H3N2, H5N1, etc.
These subtypes can infect various animal species, including birds (avian flu), pigs (swine flu), and humans. Some subtypes primarily affect animals but can occasionally jump to humans, sometimes causing severe disease or even pandemics.
Avian Flu Outbreak in Hong Kong 1997
The question asks about a specific influenza A virus subtype responsible for a severe avian flu outbreak and human disease in Hong Kong in the year 1997. This event was significant as it marked the first known instance of direct transmission of an avian influenza virus to humans, causing severe illness and fatalities.
H5N1 and the 1997 Outbreak
The subtype of influenza A virus that caused this particular outbreak in 1997 in Hong Kong and is known for causing severe avian flu is H5N1.
- H5N1 is a highly pathogenic avian influenza virus.
- It primarily affects birds but can infect humans and other mammals.
- The 1997 Hong Kong outbreak involved H5N1 causing respiratory illness in humans, linked to exposure to infected poultry.
- This event led to the culling of millions of chickens to control the spread.
Comparing Subtypes
Let's look at the other options provided and why they are not the correct answer for the 1997 Hong Kong avian flu outbreak:
- H1N1: This subtype is well-known for causing human seasonal flu and was responsible for the 1918 Spanish flu pandemic and the 2009 swine flu pandemic. While it affects humans, it is not primarily known for the 1997 avian flu outbreak.
- H7N7: This subtype has caused some avian flu outbreaks and sporadic human infections, but the 1997 Hong Kong event is specifically associated with H5N1.
- H3N2: This is another common subtype that causes seasonal human flu and has been circulating in humans for many decades. It is not linked to the 1997 avian flu outbreak.
Therefore, the influenza A virus subtype responsible for the severe avian flu outbreak and human cases in Hong Kong in 1997 was H5N1.
Important Questions from Immune System
Bacterial infections are generally divided into two broad classes: intracellular and extracellular bacterial infections. Given below are some of the properties which are applicable for bacterial infections.
A. Humoral immune response is the main protective response against extracellular bacteria.
B. Innate immunity is not effective against intracellular bacterial pathogens.
C. Bacterial endotoxins do not induce an innate immune response.
D. Intracellular bacterial infections generally induce a cell-mediated immune response resulting in secretion of cytokines which activate macrophages.
Which one of the following combination of statements is correct?
The immunoglobulin heavy-chain that is rearranged first and is displayed on the surface of early stages of B-cell development is associated with:
Dr. Ralph M. Steinman was awarded Nobel Prize for his discovery on:
Which one of the following systems forms a chemical mediator that is involved in the mechanism of pain during inflammation?
Suresh was bitten by a poisonous snake and was immediately treated with anti-venom human immunoglobulin and was saved. A year later he was bitten by the same type of snake second time. Predict his response to the venom from second bite from the following:
