General Virus Basics

How viruses cause disease

Viruses are microscopic particles that cause disease. There are many known diseases in humans caused by viruses, including, but not limited to, influenza, AIDS, and the common cold. Viruses also cause disease in other organisms besides humans, such as plants, insects, and bacteria.

The process in which viruses cause disease is as follows:

1. Viruses enter cells by connecting to a receptor on the cell's surface, and inject their genetic material (DNA or RNA), into the cell. The virus dies afterwards.
2. The virus's genetic material travels to the nucleus, and becomes a part of the host cell's DNA.
3. The virus's genetic material directs the host cell to produce copies of the virus. These copies burst from the host cell, killing the cell.
4. These new viruses go on to infect other cells, creating more viruses. This cycle repeats itself over and over, causing disease.

 

Structure

Basically, viruses consist of genetic material, and a protein shell that encases the genetic material.The genetic material of the virus consists of either RNA or DNA, depending on the type of virus. The characteristics of the virus is contained in and controlled by the genetic material. A virus’s genetic material can also be described as the instructions to make a virus. When a virus infects a cell, its genetic material uses the cell to make copies of the virus (using the information contained in the DNA/RNA).

The protein shell is the outer part of the virus. On the outside of the shell, there are spike-like structures, called surface proteins. These surface proteins are like “keys” to enter and exit the cell. Viruses use surface proteins to enter a cell to infect it. After the cell makes copies of the virus, the copies use surface proteins to exit the cell.