APOLIPOPROTEINS - ANTIVIRAL AGENT?

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 HIV has been a controversial topic in the past few years. But still, there is no vaccine for it. There is a natural tendency for the body to fight against foreign particles which is referred to as immunity. But, how is it that, your body doesn't even try to fight of this virus? Or it does, but it is still not that effective?

Let's find out it in this blog.


This is a basic structure of HIV virus. All bumpy with lots of receptors.


This image shows the detailed inside structure of HIV.

The basic thing to note here is that, HIV is a RETROVIRUS belonging to the family called as Lentiviridae. Retrovirus means the virus who can turn RNA into DNA and RNA being the primary genetic material. The enzyme Reverse transcriptase helps in the conversion of the viral RNA into the DNA, which is then added into the Host's DNA to carry out the life cycle.

As the Virus enters the body, it has a affinity towards the CD4 cells (a part of White blood cell family).
This causes reduction in number of White Blood Cells and thus results in a wide variety of diseases. Hence it is called as AIDS/Acquired Immuno-Deficiency Syndrome.
Due to this fact that it attacks WBC's, our body has now started to form anti-retroviral antibodies that are helping in fighting off this infection, but due to the HIGH mutation Rate of the Virus, the functionality of these anti-retroviral antibodies is less effective.


Let us now take a look at Apolipoproteins. APO or Apolipoproteins are structures that are formed of 2 components; one lipid and other is a non lipid part called as Protein. This conglomeration helps in transport of certain substances in and out of the cell.



This is how APO's are there in a molecule, that helps in transfer in and out of the cell.

There are various Categories of APO and one of the which has came into light is APOBEC3G.

It is made of 2 components. APOB - made of 2 subunits of B100 and B-48. where as EC3G - is made of 3-Cytidine Deaminase. This is a group of enzyme that is responsible for the immune reaction.

What actually happens is, When the virus enters the body, This APO is triggered and this enters the virus. On entering it identifies the Uracil Component. Since it has RNA, it binds to the Uracil as uracil and cytosine are analogues. Or if the RNA is transcribed into DNA, it binds to the Cytosine moiety.

This binding causes a change in the base pair and thus the whole sequence changes. Example, if the RNA has AUUGU, the APOBEC3G will bind to the Uracil and cause a change that will lead to the counterstrand formation in the order of TGGCG. This may not look so much significant, but this small error in reading of the base pairs by the viral enzymes will cause defective synthesis of the further Genetic material leading to the death of the virus itself or production of non functional viruses that have lost its infective potential.

But this is not true for every case. Since the genetic material has a VIF gene as can be seen in this image; this VIF plays a crucial role in the survival of the virus.



This VIF stands for Viral InFectivity protein. This VIF attaches itself to the APOBEC3G and causes degradation of APOBEC3G, thus maintaining the viral infectivity. 

Hence, the effectivity of APOBEC3G is still under research and if we can enhance it's functionality and resistance to VIF, maybe we can fight off HIV.

WARNING: This is a blog which is based on pure research. No false information is being conveyed. The example of AUUGU given above is just for explanatory purpose. There are various other such proteins present in the body other than APOBEC3G, on which the research is going on. This is a recent discovery and is being under monitor since 2013-2014. 

 Contact us  - @_uzumakisenpai_  @creativesparkblogs

Author - Dr. Yogiraj Karambelkar

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