Question

How does H1N1 (influenza) enter its host cells? How does it exit its host cells? What causes small changes in the flu every year and why haven't we gotten rid of it completely?

Answer 1

The influenza (H1N1) entersthe host cell by having its hemagglutin bind to the sialic acid found on the glycoprotein or glycolipid receptor of the host cells.The cell then endocytoses the virus .In the acidic environment of the endosomes , the virus changes its shape and fuses with the envelope with the endosomal membrane .This is followed by a signal to release the virus nucelocapsid into the host cytoplasm .From there, the virus travel to the host cell.

In the host cell, the virus does primary transcription to produce necessary proteins for replication.That primary transcription is known as "cap snatching".It means that viral endonuclease cuts the 5' methylguanosine cap as well as ten to thirteen nucleotides from the RNA.This is used as primer for the transcription of the protein PB1,a viral transcriptase Thus how it exits in host cell.

Flu changes every year in two ways

a)Antigenic shift;- It is the process by which two or more differnt strains of virus or strain of two or more different virus combine to form a new subtype having a mixture of the surface of the antigens of the  two or more origial strain.

b)Antigenic drift:-It is akind if genetic variation in viruses arising by the accumulation of mutations in the virus genes that code for virus surface proteins that host antibodies recognize.

We cannot get rid of the influenza because a person infected with influenza virus and the second time with a regular seseaonal virus.Most rapid test cannot distinguish which influenza virus is responsible for the illness.And also influenza test can occasionally give false positive and false negative results so it is possible that one of the test result is incorrect.So we cannot get rid of it.