Icing on the Ice – The icosahedral virus

A virus is simply an infectious agent which can only replicates within a host organism; however, the term virus may also apply to a type of virus which causes disease, like retroviruses, bacterial viruses, etc. Most viruses are quite small in size, often less than a micrometer in length, and they typically only require a living host in order to multiply. Most viruses have a very general structure, and they are so small that even a standard microscope is not required to see them.

There are two different processes called viral transcription and viral replication. Transcription involves the protein synthesis needed to initiate the assembly of the virus proteins. This requires the transcription of specific DNA sequences. Once the DNA is transcribed, the sequence is then replicated by a process called genetic replication. The next step is for the newly created virus to enter the cell for infection.

Viral replication occurs in a process called nucleation. Nucleation is a process whereby a large molecule is transformed into a smaller molecule while in the process of viral replication. In this instance, the nucleic acid encoding the viral protein is also changed, but not before the viral RNA strands bond together. The viral RNA is passed on to various cells of the body, where it replicates again until the desired end result is achieved.

Infection occurs when the correctly catalyzed DNA strands bond with host cells. Once the DNA strands bond, the infected cells replicate uncontrollably, forming the viruses. The most common way viruses are spread is through contact with bodily fluids, although other ways are also possible, depending upon the type of virus. Some viruses, for example, remain stuck on the surfaces of host cells, waiting for a triggering factor which allows them to jump to a new cell.

There are various ways to recognize whether a particular strain of a virus has become active (i.e. the virus is growing in size). For instance, if we are comparing two cultures that are completely similar in all respects except for their culture of bacteria, we can immediately see whether the differences are growing. If we find that one culture has more colonies of a certain strain than the other, then we would say that strain X has become active. This is not the only way to identify active viruses; various experiments have been carried out using PCR and various types of analysis equipment to detect viral activity.

Of the known icosahedral viruses, two viruses account for nearly half the total number of cases diagnosed every year. One of these, Listeria, accounts for almost 25% of cases globally. Another is Ebstein Barr, a strain of herpes simplex virus that causes cold sores and fever blisters, that can also infect healthy individuals. The third strain, SARS-1, has so far caused the most deaths, with over 5% of cases in the past few years occurring in the USA.