In order for viruses to reproduce, they must infect a cell, this part we understand. But do we really know how the most devastating of all Viruses and the smartest one of all times really works?
Once i was told that in order to provide an accurate answer i need to understand the question, and of course the subject. The HIV Virus is the ultimate question of our time and we need to be able to understand it if we want to be able to eradicate this threat.
Viruses are not technically alive: they are sort of like a brain with no body. In order to make new viruses, they must hi-jack a cell, and use it to make new viruses. Just as your body is constantly making new skin cells, or new blood cells, each cell often makes new proteins in order to stay alive and to reproduce itself. Viruses hide their own DNA in the DNA of the cell, and then, when the cell tries to make new proteins, it accidentally makes new viruses as well. HIV mostly infects cells in the immune system.
Scientists have discovered that specific microRNAs (non-coding RNAs that interfere with gene expression) reduce HIV replication and infectivity in human T-cells. In particular, miR29 plays a key role in controlling the HIV life cycle. The study suggests that HIV may have co-opted this cellular defense mechanism to help the virus hide from the immune system and antiviral drugs.
Replication: Once HIV binds to a cell, it hides HIV DNA inside the cell’s DNA: this turns the cell into a sort of HIV factory.
The microRNA miR29 suppresses translation of the HIV-1 genome by transporting the HIV mRNA to processing-bodies (P-bodies), where they are stored or destroyed. This results in a reduction of viral replication and infectivity.
Infection: Several different kinds of cells have proteins on their surface that are called CD4 receptors. HIV searches for cells that have CD4 surface receptors, because this particular protein enables the virus to bind to the cell. Although HIV infects a variety of cells, its main target is the T4-lymphocyte (also called the “T-helper cell”), a kind of white blood cell that has lots of CD4 receptors. The T4-cell is responsible for warning your immune system that there are invaders in the system.
Scientis think the virus may use this mechanism to modulate its own life cycle, and we can use this to our advantage in developing new drugs for HIV Retroviral therapies greatly reduce viral load but cannot entirely eliminate it. This interaction between HIV and miR29 may contribute to that inability. Perhaps, by targeting miR29, we can force HIV into a more active state and improve our ability to eliminate it.
The team of Scientist managed to looked at miR29 expression levels in infected and uninfected cells and found that miR29 expression was enhanced by HIV-1 infection. Blocking the activity of miR29 with interfering RNA resulted in increased replication and infectivity of the virus. The scientists tested the association of miR29 and HIV-1 by mutating both miR29 and its target region on the HIV virus. When either was altered, miR29s suppression of HIV replication and infectivity was reduced or eliminated. In addition, the team suppressed P-bodies in the cells and noted a similar effect. This suggests that HIV may use miRNAs to become dormant and escape immune response.