Human Immunodeficiency Virus (HIV)

Background

HIV, or human immunodeficiency virus, that is transmitted through contact and transfer of blood, semen, and other fluids. This type of virus is unique in its infection, as it is classified as a retrovirus, a family of viruses that make use of the protein reverse transcriptase to integrate its genome into the host DNA and preserve its genetic material in the multiple divisions of the cell. After learning about this novel mechanism in school, I wanted to explore the impact of this virus further and how medical professionals approach the treatment of this virus, which does not yet have an end-all cure.

What is HIV?

HIV is an RNA virus that contains a genome of RNA material. The genome codes for the nine genes of the virus, and is sheltered by the viral capsid. The virion particle also contains many enzymes like reverse transcriptase, proteases, nucleases, and integrases. On the surface of the virus particle is the nuclear envelope, which has glycoprotein complexes embedded in the phospholipid bilayer. Glycoproteins like gp120 and gp41 serve as anchors for the virus to attach to target cells and enter the cell by fusing the nuclear envelope with the cell membrane.

The main treatment for HIV is currently combination drug therapy, which involves administering multiple antiretroviral drugs to maintain the viral load.

Mechanism

HIV’s primary target is the immune system, mainly the helper T-cells of the immune system. These lymphocytes are involved in activating B cells, which can produce antibodies and remember the pathogen for future infections. By binding to the CD4 receptor on these T cells, the HIV virus can release its genetic material along with its proteins into the host cell. Reverse transcriptase uses the viral RNA as a template to create complementary double stranded DNA. This DNA is then incorporated into the host cell’s DNA. Whenever the cell undergoes transcription and translation, the viral genes are also expressed, forcing the cell to create viral proteins and manufacture multiple viral copies. With new copies being created, the virus is able to leave and rupture the cell, as well as infect other immune cells. Whenever the cell undergoes mitotic division, because the disease has incorporated its genome into the host, the viral DNA will also be replicated, ensuring that the virus is passed onto the daughter cells as well.

Discussion/Future direction

HIV does not directly kill the host, but it does make it possible for diseases to kill the host easily. Because HIV targets the immune system, when a lot of the helper T cells die, the disease shifts from HIV to AIDS (acquired immunodeficiency syndrome), Opportunistic infections like the common cold and the flu can infect the host and now it can do more damage to the host, even though it would normally not be able to. Although currently there are drugs to maintain the viral population, one potential direction for scientists to research could be the creation of drugs that destroy reverse transcriptase like endonucleases. As we learned, nucleases cut apart certain sequences of genetic material, and the entire function of HIV is based on the use of reverse transcriptase. By inhibiting this enzyme through the destruction of the primary sequence, it would inhibit the proliferation of the virus.

_ By: Kaushik Kasturi _ (External student, guest post on the request of Mentors)

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The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of Elio Academy.