HIV/AIDs

Human Immunodeficiency Virus, also referred to as HIV, is a viral infection spread through various bodily fluids. These vectors include blood, pre-seminal fluid, semen, breast milk, vaginal fluids, and rectal fluids. Contrary to popular belief, the HIV virus cannot spread through saliva. In order for the virus to spread, itmust come into contact with mucous membranes located in varying sections of the body or damaged tissue. Through these, the HIV virus can be injected into the bloodstream. The typical person to person spread is known as HIV transmission; when HIV is transmitted from a woman to her child during pregnancy, birth or breastfeeding, it is called mother-to-child transmission.¹⁾

Individuals who have HIV become immunocompromised because HIV directly attacks the cluster of differentiation 4 cells (CD4), a type of T cell, which help theimmune system fight off infection. When compromised, CD4 levels drop making an individual with HIV more likely to contract infections because their immune system is not at full strength. At the late stage of infection, a person is considered to have developed acquired immune deficiency syndrome; at this point, they will have an extremely low amount of CD4 cells and a high amount of HIV RNA present.²⁾

HIV has a seven step life cycle. The first step, known as binding, occurs when HIV connects to the receptors on CD4’s cell surface– these are known as CD4 receptors. During this process, a primary set of receptors attaches to the surface proteins of HIV which causes a conformational change to a secondary pair of receptors leading to further cell-to-cell binding.

Next, fusion occurs between the HIV envelope and the cell’s membrane; it is at this point that the HIV’s genetic information is inserted into the host cell.

The third step occurs when reverse transcriptase reads the HIV single stranded ribonucleic acid (RNA). During the first round of transcription, reverse transcriptase converts HIV RNA to single stranded deoxyribonucleic acid (DNA). Reverse transcriptase then reads it for a second round to convert the single stranded DNA into double stranded DNA. Overall, reverse transcriptase is very error prone, leading to frequent nucleotide changes. These errors contribute to HIV’s drug resistance because the DNA sequence is always changing. The multitude of changes lead to a single drug being insufficient for treating HIV.

Once double stranded HIV DNA is created, integrace carries it into the host cell’s nucleus where it is inserted into the cell’s DNA; at this point, the individual who contracted HIV has it for life, even if they are treated. After this integration, the cell begins producing the host cell proteins as well as HIV proteins. These HIV proteins are the beginning of a new HIV cell.

\During step six, which is also known as assembly, the new HIV proteins are carried to the cell surface where they become immature, noninfectious HIV.

In step seven, budding occurs. Here, the new HIV breaks off of the host cell. Once separated, protease breaks up the long chains of protein in the new HIV cell turning the immature HIV to mature HIV. It is at this point where the cell is fully functional and can go infect other cells.³⁾