A retrovirus is a throw in of RNA virus.
RNA viruses have genes encoded in RNA instead of DNA.
Infection by a retrovirus, however, requires an additional step.
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Retroviruses are “retro” because they reverse the direction of the normal gene-copying process.
Usually, cells convert DNA into RNA so that it can be made into proteins.
But with retroviruses, the process has to start by going backward.
This article looks at how retroviruses work.
It also provides some examples of known retroviruses.
It does this with an enzyme called reversetranscriptase.
Retroviruses use reverse transcriptase to transform their single-stranded RNA into double-stranded DNA.
DNA molecules store the genetic information of human cells and cells from other life forms.
Once transformed from RNA to DNA, the viral DNA is integrated into the genome of the infected cells.
When this happens, the cells are tricked into copying these genes as part of the normal replication process.
The cell can also transcribe the DNA back into RNA as the first step in making viral proteins.
For example, scientists have used retroviruses to help diabetic rats make their own insulin.
The most well-known of these are HIV and human T-cell lymphotropic virus.
HIV viruses are related to simian immunodeficiency virus (SIV), a Lentivirus that infects non-human primates.
HTLV-1 is associated with certain leukemias and lymphomas.
The lifetime risk for leukemia/lymphoma among people infected with HTLV-1 is about 5%.
The retroviruses that infect humans are spread in bodily fluids.
You may get them through sexual contact or exposure to infected blood or tissue.
They can also be passed to a fetus during pregnancy or childbirth.
Retrovirus Treatment
Reverse transcriptase inhibitors are a well-knownclass of HIV drugs.
These drugs stop the HIV virus from integrating into the genome of the host cell.
Unfortunately, there are growing problems with resistance to many drugs in this class.
Chemotherapy is not usually an effective treatment for ATL.
Other Types of Viruses
Other types of viruses include DNA viruses and non-retrovirus RNA viruses.
As the name suggests, DNA viruses have genes that are coded in DNA.
Hepatitis B, human papillomaviruses, and many common respiratory viruses like adenoviruses are DNA viruses.
Some examples of non-retrovirus RNA viruses include influenza, coronavirus, West Nile virus, and Zika.
Summary
Retroviruses are unique because they replicate themselves by reverse-coding their genes into host cells.
HIV is the most well-known retrovirus that infects human beings.
Other retroviruses are known to infect different species.
Frequently Asked Questions
Most RNA viruses reproduce by inserting RNA into the host cell.
The RNA contains the instructions for making copies of the virus.
Then the cell treats it as part of its own genome and follows the instructions for making new virus.
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