What Is A Retrovirus
What is A Retrovirus

What is A Retrovirus: Definition, Classifications, 3 Groups, and Examples

What is a Retrovirus? Retroviruses are single-stranded positive-sense RNA viruses with intermediate DNA and, as obligate parasites, target host cells. Once inside the host cell cytoplasm, the virus uses its own reverse transcriptase enzyme to produce DNA from its RNA genome, the opposite of the usual pattern, making it retro. The new DNA is then inserted into the host cell genome by the integrase enzyme, at which point retroviral DNA is referred to as provirus.

The host cell then treats the viral DNA as part of its own genome, transcribing and translating the virus gene along with the cell’s own genes, producing the proteins needed to assemble a new copy of the virus.

What is A Retrovirus?

Retroviruses are viruses consisting of one or two single threads of RNA. And once the retrovirus infects the cells, the virus will form a DNA clone of the viral RNA using the reverse transcriptase enzyme. Because this process goes backwards than usual (DNA becomes RNA) hence this virus is called Retrovirus.

Retrovirus classification

Based on the organization of the genome retrovirus is divided into two major categories, namely simple and complex retroviruses. All retroviruses contain three main domains that encode virion proteins: gag, which directs the synthesis of internal proteins that will form capsids, matrix and nucleoproteins; pol, contains information for reverse transcriptase and integrase enzymes; and env, which contains and transmembrane components of the viral envelope. An additional domain commonly found in all retroviruses is the pro, which encodes virion protease.

Simple retroviruses generally contain only this element, while complex retroviruses have additional non virion regulatory proteins. Furthermore retroviruses are divided into six genera. Five of these genera show potential as oncoviruses and two more groups are lentiviruses and spumavirus. All oncogene viruses, except human T-cell leukemia virus-bovine leukemia HTLV-BLV virus is a simple retrovirus. HTLV-BLV, lentivirus and spuma virus are complex retroviruses.

Retrovirus Group

There are three retroviruses found in primates: oncornaviruses, lentiviruses, and spumaviruses. Although there are very few, the three groups of viruses at risk of transmission in humans should pass through bites, urine and feces. Here are the viruses:


There are four types of oncornavirus available in non-human primates (order) (NHP) namely Simian T-lymphotropic virus (STLV), Gibbon ape leukemia virus (GaLV), Simian sarcoma virus, and Simian retrovirus Type D (SRV).. Simian T-lymphotropic virus (STLV) is very similar to Human T-cell leukemia virus (HTLV) which is very common in Asia, Africa and America. Although there are not many cases of events, HTLV is able to cause leukemia in older persons T cells or lymphoma in infected humans.


The one very dangerous type of lentivirus is Simian immunodeficiency virus (SIV). The virus is closely related to HIV (Human Immunodeficiency Virus). The HIV 1 virus is derived from the SIV strain of chimpanzees. While the HIV 2 virus is derived from SIV sooty mangabeys. There have been a large number of African monkeys that are both wild and catches infected by SIV. The strain type varies according to the type of species. Some animals infected by this virus, still look healthy. Asian primates are not the natural hosts of SIV.

Spuma viruses

Spuma virus found in primates is a Simian Foamy Virus (SFV). The virus is found in both new and old world primates. 3.7% or 11 of the 296 people commonly associated with primates have been infected by the virus.

What is a retrovirus example?

There are several (even many) examples of retroviruses that exist for different groups. The following are examples of retroviruses from these three groups.


Examples of viruses of this genus oncornavirus are:

  • Simian T-Lymphotrophic Virus
  • Gibbon Ape Leukemia Virus
  • Simian Sarcoma Virus, and
  • Simian Retrovirus Type-D.


Examples of viruses of this group are

  • Simian Immunodeficiency Virus, and
  • Human Immunodeficiency Virus

Spuma virus

An example of a virus of this genus is the Simian Foamy Virus.


Last Updated on April 12, 2021 Reviewed by Market Health Beauty Team