I wrote a paper on HIV detailing how the virus infects people and how it takes over the immune system. I feel that the information surrounding HIV is difficult to understand for those who want an in depth understanding of HIV but are not familiar with specialized terminology. This can be overwhelming and discouraging, I hope you find this paper to be informative and easy to read!
Doctors and researchers have come a long way since the early days of medicine. From traditional Chinese medicine to today’s complex drugs and treatments, the evolution of medicine has been all but stagnant. Despite the great strides that have been made in the field, there are still many diseases that have stumped researchers and doctors. Cancer, Amyotrophic Lateral Sclerosis (ALS), and many genetic diseases have yet to be cured. One such Disease is HIV. HIV stands for Human Immunodeficiency Virus, as its name suggests, this virus causes complications in the immune
A virus is a nonliving microbe that is an obligatory intracellular parasite. What this means is that they cannot reproduce without inhabiting a host cell. This is due to the fact that viruses lack their own cellular machinery to synthesize their proteins and DNA/RNA. Although, some viruses carry enzymes with them, like reverse transcriptase, that are not present in their host cells and will allow them to be able to properly synthesize their parts and genetic material. HIV is a retrovirus meaning it has RNA instead of DNA and also contains the enzyme reverse transcriptase. This allows it to turn its RNA into DNA for synthesis of more RNA and proteins. Viruses that have a membrane covering around their protein casing, or, “enveloped viruses.” Due to HIV being an enveloped virus this also affects HIV’s mechanism of entry. Typical mechanisms of entry include endocytosis, membrane fusion, or penetration; HIV uses membrane fusion. Membrane fusion relies on peplomers, glycoprotein spikes, present on the surface of the virus that bind to the host cell’s receptors to allow entry. When the peplomers bind to receptors of the host cell, the outer membrane of HIV fuses with that of the host cell. This allows for smooth entry of HIV into the cell. Unlike active viruses which go directly into the lytic cycle of viral reproduction, HIV is a latent virus; this means that HIV spends most of its time in the lysogenic cycle. The lysogenic cycle involves integrating the viral DNA with the host’s DNA to produce a prophage. If and when the conditions are favorable, the lysogenic cycle will be stimulated and move to the lytic cycle which includes the transcription, translation, assembly, and release of the HIV virus. The fact that HIV is a latent virus makes it difficult to diagnose or even give an accurate estimate of how large the viral load of an HIV positive individual is.
HIV’s mechanism of action affecting the immune system
As previously stated before, HIV attacks the human defense system, the immune system. Something that should be noted is that HIV itself does not kill the individual, rather, the lower immune system leads to infections and cancers that an otherwise normal individual would not be susceptible to. To begin, there are two types of T cells: the T helper cells-like CD4- which aid in the proliferation of B lymphocytes-which produce antibodies- and killer T cells- which lyse infected cells. HIV infects activated CD4 cells and destroys them. This causes an overall depletion of CD4 cells. One interesting thing to note is that during the start of when the virus is detected, the CD4 and CD8 T helper cells have a high turnover during the infection; about 3-4 times higher. However the CD4 count eventually falls after this short phase of increased immune system activity. Unfortunately, it is not fully understood how exactly or why the immune system starts to falter; allowing the virus to lower the the CD4 count. In fact, why there is such a high turnover of CD4 and CD8 cells in the beginning is not understood as well. One theory for the increased turnover is that the immune system is not the one responding to the infection, rather, “a large number of cells stimulated by antigen and/or inflammatory molecules rapidly replicate and subsequently die”. All in all HIV causes a decline in CD4 T cells and it is that decline that causes individuals to progress to the more serious stage of infection, AIDS.
AIDS stands for, “acquired immune deficiency syndrome” and is the late stage of HIV infection. During this stage, the immune system has been seriously damaged and the body has an extremely difficult time defending itself from foreign and pathogenic entities. As stated before, this will lead to the individual becoming infected with opportunistic infections like tuberculosis and toxoplasmosis of the brain. As stated above, these diseases are the cause of an infected individual’s death; HIV only makes it easier to become infected and harder to defend against.
