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What Are the Different Types of Viruses?

Michael Anissimov
Michael Anissimov
Michael Anissimov
Michael Anissimov

Viruses are tiny bits of genetic material, wrapped in protein envelopes, capable of hijacking the cellular machinery of plants, animals, and bacteria for self-replication. They are extremely small, much smaller than bacteria. A typical virus is between 10 and 300 nanometers (billionths of a meter) in size, whereas typical bacteria are larger than a micrometer (millionth of a meter) in size.

Only about 30,000 virus types are being tracked by virologists, although millions likely exist. Viral classification is made difficult by a lack of fossil evidence — viruses fossilize poorly — and controversy over whether they are living organisms or not. Unlike other organisms, new viruses sometimes emerge from the genomes of preexisting organisms, making it difficult to build coherent family trees. However, this doesn’t stop virologists from trying.

A boy with chickenpox.
A boy with chickenpox.

A unified taxonomy for viruses was only developed in 1966, by the International Committee on Taxonomy of Viruses (ICTV). This classification scheme is inspired by the Linnaean classification system for other organisms. It contains five levels: order, family, subfamily, genus, and species. The recognition of the order level is extremely recent, with only three orders named. Most viral families have not yet been placed in any order. Currently, the ICTV only recognizes about 1,550 species.

As an example, the chicken pox virus, Varicella zoster (VZV), belongs to the family Herpesviridae, subfamily Alphaherpesvirinae, genus Varicellovirus, and lacks a categorization based on order.

Viruses are tiny bits of genetic material, wrapped in protein envelopes, capable of hijacking the cellular machinery of plants, animals, and bacteria for self-replication.
Viruses are tiny bits of genetic material, wrapped in protein envelopes, capable of hijacking the cellular machinery of plants, animals, and bacteria for self-replication.

A second classification scheme, Baltimore Classification, developed by and named after Nobel Prize-winning biologist David Baltimore, is commonly used in conjunction with the ICTV system. The Baltimore classification system categorized viruses based on what they are made out of. However, this does not state how they can be fought off, which mean humans have to rely on tested methods like inoculations, and strengthening the immune system with healthy food and supplements like greens powder or multivitamins. Here is the scheme:

GroupContains
Idouble-stranded DNA viruses
IIsingle-stranded DNA viruses
IIIdouble-stranded RNA viruses
IV(+)single-stranded RNA viruses
V(-)single-stranded RNA viruses
VIdouble-stranded reverse-transcribing viruses
VIIdouble-stranded reverse-transcribing viruses
A typical virus is between 10 and 300 nanometers in size.
A typical virus is between 10 and 300 nanometers in size.

By using these two classification systems together, virologists can actually have a clue of what one another are talking about. Another traditional classification system is based on what type of organism they infect: there are plant-specific viruses, animal-specific viruses, and bacteria-specific viruses, called bacteriophages. Having this information makes it possible to devise a plan to protect people from severe infection symptoms whether it be through good nutrition or intake of supplements. Depending on the host the virus has evolved to infect, it will have a different physical structure. Different immune systems will also respond differently to these viruses, and although green powders and multivitamins will help, there's no definitive data regarding effectiveness. One of the methods to fight off viruses is strengthening the immune system, which can be accomplished by consuming supergreens in whatever way you find suitable.

Michael Anissimov
Michael Anissimov

Michael is a longtime WiseGEEK contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.

Learn more...
Michael Anissimov
Michael Anissimov

Michael is a longtime WiseGEEK contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.

Learn more...

Discussion Comments

helene55

@BambooForest, another problem in recent years related to fighting viruses is the growing obsession with medications and shots to treat influenza, perhaps the best known viral disease. The problem from this is that because viruses can mutate and reproduce so easily, and are so difficult to classify, an increase in products such as Tamiflu has only led to a growth in stronger flu strains. This problem is similar to what happens when an area is sprayed for mosquitoes; nearly all of the insects die, but the ones which survive had the highest resistance, leading to later generations have that stronger resistance.

Additionally, the problem with an increase in flu shots is that there are many strains of influenza in any given flu season, and a flu shot only protects against one flu strain. Additionally, flu shots lower immunity in many people for at least a short time after they are given, often causing those people to get sick with one of the other viruses infecting the population.

BambooForest

When treating viral diseases, it is important to remember that they are different from bacteria, and therefore are impervious to antibiotics. In recent years, an increase in the prescription of antibiotics, both through ignorance of doctors and demands of patients, has caused an increase of other health problems, but has done nothing to help prevent the spread and growth of viruses.

somerset

Viruses completely depend on the host cells for replication of their nucleic acid.

They are heat sensitive and susceptible to agents that can damage their nucleic acid.

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    • A boy with chickenpox.
      By: Dan Race
      A boy with chickenpox.
    • Viruses are tiny bits of genetic material, wrapped in protein envelopes, capable of hijacking the cellular machinery of plants, animals, and bacteria for self-replication.
      By: Yang MingQi
      Viruses are tiny bits of genetic material, wrapped in protein envelopes, capable of hijacking the cellular machinery of plants, animals, and bacteria for self-replication.
    • A typical virus is between 10 and 300 nanometers in size.
      By: RTimages
      A typical virus is between 10 and 300 nanometers in size.
    • A stomach virus can cause symptoms including nausea, cramps and vomiting.
      By: Kaspars Grinvalds
      A stomach virus can cause symptoms including nausea, cramps and vomiting.
    • Individuals should wash their hands frequently with soap and warm water to prevent the spread of viral infections.
      By: nito
      Individuals should wash their hands frequently with soap and warm water to prevent the spread of viral infections.