Retrovirus - an overview

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Retrovirus - an overview

Retroviruses are viruses whose genetic material is RNA. They are retroviruses that are members of the Retroviridae family. After infecting a cell, it uses reverse transcription to change the RNA therein into DNA. After that, the host cell's DNA is exposed to this viral DNA, and it begins to replicate there. The Human Immunodeficiency Virus (HIV), for instance.

Structure of Retroviruses
Meaning of a retrovirus: A class of RNA viruses that replicate by introducing a DNA copy of their genome into their host cell.


The envelope protein complex is embedded in the lipid bilayer, which is composed of two concentric outer circles. Hexagonal proteins make up capsids. The RNA genome is replicated in a loop that is held together by nucleoproteins.

 
The principal parts of a virion are:


Wallet
Env genes encode glycoproteins and lipids that make up the retroviral envelope. It fulfills three crucial purposes:

Envelope 
Env genes encode glycoproteins and lipids that make up the retroviral envelope. It fulfills three crucial purposes:
The extracellular environment is shielded from the retrovirus by the lipid bilayer.
facilitates the endosomal membrane trafficking that allows the retrovirus to enter or exit the host cell.
direct access by merging with the membranes to enter the cells.

 
RNA
It is made up of a dimer RNA with a 3′ poly-A tail and a 5′ cap. While the interior portions encode virion proteins for gene expression, the terminal non-coding areas aid in replication.

Proteins
Gag, pol, protease, and env proteins make up this complex.
Vectors of Retroviral
Genetically modified retroviruses are known as retroviral vectors. For more than 20 years, they have been utilized to introduce genes into the host cells of mammals.
The most prevalent retrovirus is the Moloney murine leukaemia virus, which is the source of retroviral vectors.
Within the host cell's genome, they are able to integrate and reproduce with efficiency. They have been employed as vectors in a variety of gene therapies because of this.
Therapeutic genes are substituted for the gag, pol, and env genes to form the retroviral vectors.

The ability of the integrase enzyme to insert genetic material between the host cell's own genes is one of the drawbacks of employing retroviral vectors in gene therapy. The disruption of the gene is caused by this.


Examples of Retroviruses
Humans are impacted by three different kinds of retroviruses:
HIV

HIV targets a person's immune system. The CD4 T-cells, which are in charge of defending against infections, are destroyed by it. As a result, a person's immune system gets progressively weaker. It can be passed from mother to kid during childbirth or nursing, by needles, or through bodily fluids. It cannot be treated with drugs or other therapies. The final stage of HIV infection is known as AIDS, and it results in death.

Types I and II of the Human T-cell Lymphotropic Virus (HTLV) are closely linked to one another. An individual with HTLV I viral infection gets acute T-cell leukemia. It results in a neurological condition by affecting the spinal cord. It is the first known human retrovirus and can be spread by intercourse, breast milk, sharing needles, and blood transfusions. Additionally linked to neurological conditions and certain blood malignancies is HTLV II. Still, not much is understood about this kind of virus.

Endogenous Retrovirus
The genetic material from those extinct viruses whose genetic makeup is comparable to that of the current retroviruses makes up the endogenous retroviruses. Over time, as humans have evolved, these viruses have spread across the population. They are inherited by future generations and make up 5% of the human genome.

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