(a)*CLASSIFICATION OF AVIAN INFLUENZA "BIRD FLU"*

Classification of Avian flu Virus
-Types of Flu viruses
In the orthomyxoviridae flu virus family, there are three types of flu viruses: type A, type B, and type C. The avian flu virus is a type A virus.
Type A viruses are the most dangerous. They can infect a wide range of organisms, including birds, humans, and pigs. There are also subtypes of type A viruses, classified by the type of surface proteins on the viruses. These viruses can also cause both local epidemics and global pandemics.

-Subtypes
Influenza viruses have two kinds of surface proteins: hemagglutinin and neuraminidase. There are different types of hemagglutinin (H) and neuraminidase (N) surface proteins. There are 16 types of H surface proteins and 9 types of N surface proteins (which are named H1, H2, N1, N2, etc.). An influenza virus always has one type of H surface protein, and one type of N surface protein.
Influenza virus subtypes are classified and named according to the types of H and N surface proteins on the virus. For example, a subtype named H6N4 would indicate that the virus has type 6 hemagglutinin surface proteins, and type 4 neuraminidase surface proteins.
There are many subtypes of influenza viruses that cause avian flu. The most notable of these avian flu virus subtypes is H5N1.
Different subtypes of virus, H7N2, H3N1, and H7N1.

-Strains
Within these subtypes, there are strains of viruses with slightly different genetic sequences, caused by random mutations in the viruses’ RNA over time. These mutations can cause small changes in the viruses’ characteristics, but if the strains have the same surface proteins, they are classified as the same subtype. These strains can be described as slight variations on the same virus.