The flu virus is the causative agent of influenza. The virus is transmitted by airborne droplets expelled via cough or sneezing. There are several parts for the virus, which affects how the vaccines against the virus are made and also how antiviral medicines work against it.
Hemagluttinin
Hemagluttinin is one of the important surface proteins of the influenza virus. It is the H in the designation of these viruses---for example, H1N1. This is one of the proteins our immune system targets to defend itself against infection. This protein received its name because it causes hemagluttination, or clumping of red blood cells. There are several H proteins, depending on the virus that is circulating in a specific year, and antibodies against one will not protect against the others, which is part of the reason we need yearly influenza shots. The hemagluttinin proteins are also important for the binding of the virus to cells, which makes it the primary protein in the process of transmission and spread of the flu virus.
Neuraminidase
Neuraminidase is the other main protein on the surface of the flu virus. This protein helps new viruses that grow on infected cells to bud off, enhancing replication and propagation of the virus. The anti-influenza drugs, for example Tamiflu, are neuraminidase inhibitors, target this protein and prevent replication of the virus, decreasing the amount of time a patient has symptoms of the infection.
M2 Ion Channel
The M2 ion channel part of the virus allows hydrogen to go inside the virus, helping it replicate. The other class of drug that fights off the influenza virus is the adamantine antivirals, for example amantadine. These drugs target the M2 ion channel, preventing the replication of the virus. This channel can easily change, thus creating resistance against these medicines.
RNA
Ribonucleic acid (RNA) contains the genetic information for the viral machinery, replication and production of proteins. RNA replicates inside infected cells and buds off as new viruses, spreading the infection throughout the body.
