Viral Infection - Influenza

Viral Infection-Influenza Introduction :-

 Influenza virus
 Influenza virus

Influenza virus has now included in the Family Orthomyxoviridae (Greek - Orthos- Correct, Myxa - Mucus) by the international committee for the taxonomy of viruses because influenza virus has the ability to bind to the mucus. Influenza virus affects the central respiratory system in the Birds, Horses, Humans also etc.
Influenza is one of the widespread human disease, influenza virus affects 15-20% of the US population, and is killing up to 50,000 individuals in USA.

 Influenza virus
 Influenza virus

Type of Influenza viruses -

Influenza viruses are of 3 types and are distinguished on the basis of the antigenic difference between their Nucleocapsid and Matrix proteins.

Generally influenza viruses are of 3 types -

1) Type A influenza viruses

2) Type B influenza viruses

3) Type C influenza viruses

Out of 3 types of influenza viruses type A & B viruses encode three integral membrane proteins Haemagglutinin (HA), Neuraminidase (NA) and M2 (Influenza A virus) or NB (Influenza B virus).
But Influenza C viruses encodes only two integral membrane proteins, HEF & CM2.

Influenza A virus can cross the barriers (or species barrier) into farm animals and humans. influenza B virus is usually found in the Humans and are less harmful then influenza A viruses.

But out of them Influenza C virus causes the only a mild illness in the humans and cannot causes any epidemics.

Internalization of Influenza virus :-

The influenza virus enters into the host cell by Endocytosis process (receptor mediated endocytosis) through clathrin coated pits

after internalization into the host cell virus containing the coated vesicles these coated vesicles then un-coats and fuses with the endosomes having Acidic PH. then the spikes of the virus mediates fusion of the endosome membrane and the viral membrane and the all of the viral RNA enters in cytosol, where the replication and expression of viral proteins takes place. But in this fusion process rod shaped spikes of  Haemagglutinin play their major role. 

Generally spikes are of two types :-

1) Rod shaped spikes of Haemagglutinin

2) Mushroom shaped spikes of Neuraminidase (NA) glycoproteins     

one of the main function of the Neuraminidase is permitting the transport of the virus through the mucus layer of the respiratory tract and enabling the virus to find the target epithelial cells.

Immune response against Influenza virus -

Antibody protects the human body against the influenza virus and these antibodies specific for the Haemagglutinin molecule.

These antibodies are usually directed against the conserved sialic acid binding cleft of haemagglutinin, that is very necessary for the binding of virus to the target cells.

The antibodies against influenza virus remain in circulation for several months to several years and provides resistance against Re-infection by the same strain of influenza viruses.

Symptoms of Influenza -

The common symptoms of influenza virus are - Vomiting, Fever, Headache, Runny nose, aches, Coughing etc.

 Influenza virus

Symptoms of Influenza virus

Treatment -

 Influenza virus

Treatment of patients with influenza mainly has only several aims but the common aim is - Patient that has affected by influenza will receive specific Treatment Anti viral Drugs for Influenza.

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