HIV infection leaves a ‘memory’ in cells
The human immunodeficiency virus (HIV) causes acquired immunodeficiency syndrome (AIDS). One of the most distinguishing features of HIV is its ability to establish long-lived infections, in some people for decades. A new study has found that this is because the virus leaves a “memory” in infected cells.
HIV infection persists for many years because the virus establishes a pool of long-lived, latently infected cells. These latently infected cells harbor a provirus, which is a dormant, viral genome integrated into the cells’ DNA. The provirus can reactivate and start producing new virus particles at any time.
The new study, published in the journal Nature, shows that the provirus is not just a “dumb” passenger in the cells. Rather, it somehow alters the cells’ genome in a way that allows the virus to reactivate more easily.
In the study, the researchers infected human cells in the laboratory with HIV. They then looked at the cells’ DNA to see if there were any changes caused by the provirus.
They found that the provirus caused changes in the epigenome, which is the chemical modification of the genome that can turn genes on or off. Specifically, the provirus caused changes in a group of enzymes called histone deacetylases (HDACs).
HDACs are known to be involved in the establishment of latent infections. The new findings suggest that the provirus causes changes in HDACs that make it easier for the virus to reactivate.
The findings could have important implications for the development of new treatments for HIV. Current antiretroviral therapies can suppress the virus, but they cannot clear it from the body. This is because the virus can hide in latently infected cells and reactivate at any time.
The new findings suggest that it may be possible to develop therapies that target the provirus itself. Such therapies could potentially clear the virus from the body and cure HIV infection.
The study was conducted by researchers from the Ragon Institute of MGH, MIT and Harvard, the Broad Institute, and Harvard Medical School.
HIV infection leaves a ‘memory’ in cells
by Dr. Sarah
HIV is a byproduct of the human immunodeficiency virus. The human immunodeficiency virus, or HIV, is a Retrovirus that primarily infects vital cells in the human immune system such as macrophages and helper T-cells. These cells are important in the body’s fight against infection and disease. When HIV enters the body, it hijacks the cells it infected and uses them to reproduce. As the infection progresses, more and more cells are infected and eventually the immune system is overwhelmed. This can lead to Acquired Immunodeficiency Syndrome (AIDS), a debilitating and often deadly disease.
But even after the infection is controlled, HIV leaves a lasting legacy: a ‘memory’ of the infection in the form of RNA. This RNA is a copy of the viral genome and is found in infected cells even after the virus is no longer active. This RNA serves as a reminder to the immune system that the virus has been encountered before and can help the body mount a more effective response if the virus is encountered again.
RNA is a nucleic acid that is similar to DNA. It is found in all living cells and is responsible for carrying the genetic instructions of a cell. RNA is found in three forms: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). Messenger RNA carries the genetic instructions from DNA to the ribosomes, where proteins are synthesized. Transfer RNA delivers amino acids to the ribosomes for protein synthesis. Ribosomal RNA is a component of ribosomes, which are the site of protein synthesis.
HIV infection leaves a ‘memory’ of the infection in the form of RNA. This RNA is a copy of the viral genome and is found in infected cells even after the virus is no longer active. This RNA serves as a reminder to the immune system that the virus has been encountered before and can help the body mount a more effective response if the virus is encountered again.
The presence of this viral RNA ‘memory’ has important implications for the development of a vaccine for HIV. Current vaccine strategies are focused on inducing an immune response that can prevent the virus from infecting cells. But a vaccine that can also elicit an immune response that can eliminate infected cells would be more effective. The presence of viral RNA ‘memory’ in cells suggests that such a vaccine may be possible.
Further research is needed to confirm the role of viral RNA ‘memory’ in the immune response to HIV and to develop vaccines that can take advantage of this process. But the presence of this ‘memory’ provides a promising new direction for HIV vaccine research.
