Flu virus mutates itself over time that cause changes in proteins on their surface called antigens. If the immune system have been met with a certain strain of virus which had been known previously. However, if antigen-antigen is a new thing for the immune system, then the virus will be weakened.
Influenza A virus can mutate in two ways: antigenic drift or adaptive mutation, whereby the existing antigen transformed and antigenic shift or mutation of the mating process of two or more kinds of antigens. Antigenic drift, causing a small mutations in the flu virus from year to year, which attacks the human immune system but not completely. In contrast, the new H1N1 strain emerged in a way antigenic shift in pigs in Mexico
The name used because of swine flu in pigs occurred the marriage of the body or coalition of strain, whether it was genetic material from their own pigs, birds, or humans. Most humans have never affected by a number of antigens that are involved to form a new flu stain that potentially cause a pandemic
This new virus variants have been transmitted to humans from pigs to humans and eventually also be transmitted from human to human. For that much needed special attention from relevant agencies, which has the authority to resolve health problems. The virus is transmitted from human to human through coughing, sneezing or contact with an infected person. Yet not much is known how the virus works in the human body.