the photo shows The human immunodeficiency virus (HIV) attacks the immune system

the image is uploaded from BBC news


When HIV enters your body through sexual contact, transfusion with infected blood, or by injection with a needle that has infected blood in or on it, it is believed that the virus attaches to a specific type of immune cell called dendritic cell. These cells ate found in mucocutaneous areas that line the mouth, the vagina, rectum, penis and the upper gastrointestinal tract. Scientist think that these dendritic cells transport the virus from the site of infection to your lymph nodes where HIV can infect other immune cells.

HIV can infect many cells in your body, but its main target is CD4+ lymphocytes. When a CD4+ T cell is infected the virus goes through multiple steps to reproduce itself.

1.Binding and fusion: this is the process by which the virus binds to a specific type of CD4+ receptor. Once “unlocked” the receptor HIV can fuse within the host cell and release its genetic material into the cell.

2.Reverse transcription: a specific enzyme called reverse transcriptase changes the genetic material of the virus, so it can be integrated into the hosts DNA.

  1. Integration : the virus new genetic material enters the nucleus of the CD4+ T cell and uses an enzyme called integrase to integrate itself into your own genetic material, where it MAY HIDE AND STAY INACTIVE FOR SEVERAL YEARS.

4.TRANSCRIPTION:  the virus uses your own enzymes to create more of its genetic material.

5.ASSEMBLY: a special enzyme called protease cuts the longer HIV proteins into individual proteins, when these proteins come together with the virus genetic material, a new virus has been assembled.

  1. BUDDING: in this stage the virus pushes itself out of the host cell.

After the INTEGRATION there are two main pathways that the virus may follow. Either the virus hijacks our cell’s own equipment in order to make new copies of itself which then go on to infect and ultimately kill more cells, or alternatively it may enter a quiet, or dormant state establishing what is known as a latent reservoir.

Antiviral drugs have been designed to effectively disrupt different stages of the HIV life cycle, they are only able to attack actively replicating HIV. This means that while treatment can control the infection and severely reduce the amount of the virus in the body, there will be always a lingering supply that can rebound as soon as the patient stops taking the therapy.

“ If a patient stops taking the antiretroviral therapy, the infection rebounds. It is truly amazing that the virus can give rise to AIDS 20 years after the initial infection”, Cohn says.

It was believed that the predominant source of latent virus was a type of T cell, a called a long-lived memory cell, which can persist in the immune system for extended period. This type of immune cell remember particular pathogens. When these cells encounter a pathogen they have previously seen, they spur the proliferation of T cells tuned to recognize it, in a process called clonal expansion.

For the study, scientist from the Rockefeller University investigated the replicative capabilities of viruses obtained from both clonally expanded T cells and unique cells obtained from infected individuals. The researchers were able to distinguish between these cells based on the site of integration. Because the human genome is so large, the chances of the virus inserting itself exactly the same place twice are exceedingly slim. Therefore, if multiple cells had viral DNA integrated into a particular spot, these were classified as clones. To their surprise they found that clones contained defective viruses that were incapable of completing the viral life cycle. This meant that, in contrast to prior belief, clones do not appear to harbor the latent reservoir. Instead the researchers explain that the reservoir is more likely to reside in less common cells containing unique integrations.

“ While we cannot rule out the possibility that a rare clone of cells may contain an active virus, it appears most likely that latent reservoir—and the potential target for therapies meant to cure HIV—resides in the more rare single cells containing unique integrations”, Cohn says.

Many scientists believe that if HIV can be forced out of these lingering pools, than a cure can be on the cards !!


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