In these days, "Virus", a familiar word to everyone, has been referred as a dangerous threat to all of us. A sneeze in the crowd could result in the death of hundreds people. That's probably not caused by some computer viruses, but the living one. Recently, I've done few investigations on this strain of virus, Influenza in particular, and the tendency of what it will become in future. Hence, what is brought in today is some brief views of this in-depth research about the evolution of influenza viruses. The study of viruses contains many intensively difficult concepts, but we will just have an overview of these contents. Firstly, It's the original characteristics of all Influenza viruses. Though there may be variants of virus causing flu, but they were originated from one strain, the "old H1N1". "Old H1N1" was the culprit causing millions of death in Europe during the early age of 20th century. The following statement is said by Jeffery Taubenberger, a virologist: "All influenza A pandemics since [the Spanish flu pandemic], and indeed almost all cases of influenza A worldwide (excepting human infections from avian viruses such as H5N1 and H7N7), have been caused by descendants of the 1918 virus, including "drifted" H1N1 viruses and reassorted H2N2 and H3N2 viruses. The latter are composed of key genes from the 1918 virus, updated by subsequently incorporated avian influenza genes that code for novel surface proteins, making the 1918 virus indeed the "mother" of all pandemics.".
To be more specific, "old H1N1" and its descendants as well, are a strain in a virus family called Orthomyxoviridae. As a common knowledge, we know viruses are living subbacterial microorganism, containg genome as its core surrounded by protein coat. And to be more specific, Orthomyxoviridae family has single strand of RNA at its core, and a spherical protein shell makes it looks like a spiky ball.