A virus is simply an infectious agent which can only multiply within a host organism. Most viruses can infect various types of living organisms, such as animals, plants, and bacteria. Viruses have a simple viral structure, which means that they are extremely small. They don’t have any protein coat or cell wall, just a simple membrane. A virus may have millions of parasites inside of it which are the cause of disease. When a virus is discovered, it is termed a pathogen or a strain, then it is further categorized into different categories and subtypes.


Some viruses are able to enter and breed in hosts, resulting in infection. These include the herpes simplex virus, the hepatitis virus, and the Epstein-Barr virus. All of these viruses spread primarily through contact with bodily fluid and, because of their extremely small size, they are capable of entering and multiplying in a host’s body very quickly.

When a virus spreads among individuals, it is referred to as a virus, and all viruses share a common characteristic – they are made up of genetic material. For example, all forms of the cold virus, the human papilloma virus, and the Epstein-Barr virus all share a viral component which causes mutation in the host cell, which results in the development of a new strain of the virus. The mutation may be a slight change in one place (such as amino acid sequence) or across the entire genome. If a particular strain of a virus affects more than one type of organism, then it is referred to as a super virus.

Because the genetic code of living things is meant to be specific, it can be difficult to design a virus which will attack a specific target cell. The best way to combat this is to rely on complex viruses which use different methods to attack various types of organisms. Some examples of such viruses include: poliovirus which causes piroplasmosis, enteroviruses which cause gastroenteritis, enteroviruses which cause diarrhea, herpesviruses which cause various types of genital warts, and lentiviruses which cause a variety of allergies.

A non-protein virus, on the other hand, utilizes protein as its primary method of infection. It uses this method by entering the host cell through a particular organelles, such as the plasma membrane or lymph nodes, and then using the protein coatings found on the surface of the organelles to latch on to the host cell and reproduce. The most well known example of a non-protein viral particle is the cold virus. Every known virus uses a protein envelope as its entrance point into the host cell, but most viruses use only one kind of protein coat, or envelope, to latch onto the host cell. Some examples of non-protein viral particles are: shingles, cytomegalo virus, hepatitis virus, Epstein-Barr virus, and viral encephalitis virus.

Many viruses are single stranded, or enveloped viruses. These are small in size and have a double strand of DNA wrapped around their outer shell. Enveloped viruses can either be single stranded, or double stranded. The single stranded virus is the simplest to produce, but the double stranded can be more complex. Most enveloped viruses are harmless, but when they infect healthy cells, they can generate abnormal functions and even cancerous changes.