For about 100 years now, the sci fi community has continually debated over what viruses are. First seen as dangerous microbes, then as cellular organisms, and finally as harmless, external living forms, viruses today are often thought of as being somewhere in between living and non-living: they can neither reproduce themselves nor affect the behavior of living cells, but can operate both ways in that they can either kill or send a desired message to an outside observer. There are many different types of viruses out there, some of them making internal changes within living hosts’ cells, and others which infect other types of matter and change their internal genetic code without any noticeable harm. The cold virus is one such virus, which can kill off certain types of amoeba, or what are known as enveloped viruses (which do not have any outer layers). However, they may also be responsible for the formation of the small pox virus that results in the common cold.
The virus, in essence, is just a tiny version of its host cell that has changed into a more virulent version of itself. This is because, just like in bacteria, in the case of viruses, a single change in the coding can completely alter the way in which a virus works. The genome or coding of a virus is essentially the blueprint of the virus, determining all its attributes and abilities. All the information inside the virus itself is held in the genome, meaning that in order for the virus to function in the way it does, every single piece of the virus needs to contain the correct information in order for it to function. This is why a virus’s characteristics tend to be very similar to the characteristics of its host cell; it is also the reason why a virus can only infect certain types of cells (such as those in the nose, eyes, and throat).
The first step in the genetic sequence of viruses is the assembly of a pair of DNA or RNA, called a capsid. Once the capsid has been assembled, all of the necessary genetic information for the virus are located within it. In the case of most viruses, the capsid is enclosed within an envelope that surrounds the genetic material. The envelope will often contain various antibodies or other substances that will halt or attempt to destroy the viruses once the assembly of the capsid has been completed. These pathogens are known as enveloped viruses. There are two basic classes of enveloped viruses, and these are termed A and B.
Enveloped viruses are generally unable to reproduce themselves, but their ability to copy themselves is very powerful. They can divide indefinitely, with new copies being produced every time this occurs. With this power, they are able to reproduce by replicating their viral genome. This viral genome is contained within a protein coat that is coats both the virus’ protein core and the nonessential proteins that make up the virus’s ribosome. If the protein coat is broken, the virus is unable to replicate. This is how viruses get from one host cell to another.
On the other hand, the opposite is true of a dying virus. A virus that is undergoing natural cell death will begin to replicate rapidly because it no longer has an important job to perform. Natural virus death can occur in many different ways, including shutting down the immune system so the cells that it needs to replicate can’t. Another way is when the infected cell becomes stressed to the point where the cell membrane breaks down. This causes a release of chemicals that damage the DNA of the living organisms that they replicate inside.
Most viruses that cause disease belong to the Group of Viruses known as the icosahedral. Icosahedral viruses can be arranged into a complex structure called a capsid if they are of the same type. Each capsid will contain a set of genes. These capsids can be composed of pairs of amino acids that look a lot like amino acid pairs that are found in bacteria. It is possible for a virus to have more than one type of virus-type, but only one pair will be used to make a virus that will replicate itself and cause disease.