The Nature of Viruses
The Nature of Viruses
A virus is a small submicroscopic viral agent that replicates in an organism’s living cells. There are many different types of viruses in nature, but all viruses share some common features that enable them to be passed from one cell to another and affect the cell’s DNA. All viruses infect all living cells, from plants and animals to bacteria and Archaea, which include bacteria and viruses. The most damaging viruses cause disease by destroying the targeted cell, while other types of viruses act as a type of X-ray machine to damage the DNA of living cells.
Some of the most commonly known types of viruses are herpes, cold sores, rhino virus, Epstein-Barr, Lassa fever, and cytomegalovirus. These viruses need a host to survive: they must enter the host by breaking a protective protein coating on the cell wall. Once inside, they replicate rapidly, dividing several times and replicating again until they are either neutralized or destroyed by the body’s immune system. Some viruses, however, cannot divide unless the host it is attacking becomes infected.
The majority of viruses are proteins, and viruses are very complex forms of life. Proteins can code for specific functionalities in living organisms, and these genetic codes are passed along to future generations. Thus, when viruses attack a living cell, the corresponding genetic code is used to generate a protein molecule that attacks the virus instead. For example, when the Salk Institute scientists developed the HIV virus, they used genetic coding to produce a protein that infected the body’s T-cells. This virus, when it killed, produced copies of itself in its place, which led to the formation of AIDS. Other viruses have also used genetic coding to create similar proteins, resulting in the spread of various types of tumors.
The most important aspect of a virus is its protein coding, which encodes the exact set of amino acids (or bases) that make up an organism’s genetic material. The DNA or genetic code that encodes genetic material is spread by organisms among themselves (this is called genetic variation). In order for an organism to carry the genetic material that codes for a particular disease, it must be able to reproduce. Therefore, all viruses require some form of protection from outside organisms. This is done by the ability of the organisms to generate their own immunity to protect them from an invading virus or bacteria.
The immunity produced by an organism depends on its ability to divide and reproduce itself properly. If the DNA or genetic material of an invading virus is improperly coded, the virus will not be able to reproduce, or spread itself properly. An organism’s ability to reproduce itself is dependent on its environment. A virus that can only infect healthy cells will fail to spread, while a virus that causes death of only healthy cells will be unable to reproduce. In order to successfully spread and reproduce, a virus needs to find a way of entering a cell’s cytoplasm – the fluid that is constantly produced by a cell.
Nucleic acid polymerase proteins (NAPPs) are essential in helping cells produce both nucleic acid and DNA, as well as the protein needed to activate the DNA and RNA transcription systems. For many viruses, a single genetic code or set of genetic instructions is all they need to reproduce. However, when the viral agent mutates, it can either add new genetic instructions or make changes that can confuse the cell’s machinery leading to increased mutation rates and hence, the ability of the virus to multiply and spread rapidly without limits.