HIV & AIDS - signs, symptoms, transmission, causes & pathology

Summary

The script explains HIV, focusing on its two types, HIV-1 and HIV-2, with HIV-1 being more prevalent. It details how HIV targets CD4+ cells, using gp120 to bind and enter cells, and replicates by integrating into the host's DNA. The video outlines the progression from acute infection to AIDS, highlighting the immune system's decline and the emergence of AIDS-defining conditions. It also covers transmission modes and the importance of HIV testing and antiretroviral therapy in managing the disease, emphasizing the lack of a cure but the potential for a healthier life with treatment.

Takeaways

• 😷 HIV is a virus that attacks the immune system, leading to immunodeficiency and increasing the risk of infections and tumors.
• 🌐 HIV-1 is the primary cause of AIDS globally, while HIV-2 is rare and mostly found in western Africa and southern Asia.
• 🔬 HIV targets CD4+ cells, including macrophages, T-helper cells, and dendritic cells, which are crucial for immune response.
• 🔗 The virus enters cells by binding to the CD4 molecule and a co-receptor, typically CCR5 or CXCR4, using its gp120 protein.
• 🧬 Some individuals have genetic mutations in CCR5 that confer resistance to HIV, as the virus cannot enter cells lacking these receptors.
• 📚 HIV is a retrovirus that uses reverse transcriptase to convert its RNA into proviral DNA, which integrates into the host's genome.
• 📈 After acute infection, HIV enters a chronic phase where it continues to replicate and mutate, potentially leading to an X4 strain targeting T-cells more aggressively.
• 🩺 HIV infection progresses to AIDS when T cell counts drop significantly, leading to severe immunodeficiency and life-threatening infections.
• 💉 There is no cure for AIDS, but antiretroviral therapy (ART) can manage the condition, slowing viral replication and allowing the immune system to recover.
• 🩸 HIV is primarily transmitted through sexual intercourse, but can also spread via intravenous drug use, mother-to-child transmission, and less commonly, through needlesticks and blood products.

Q & A

What is HIV and how does it affect the immune system?

HIV, or human immunodeficiency virus, targets cells in the immune system, particularly CD4+ cells like macrophages, T-helper cells, and dendritic cells. Over time, it leads to immunodeficiency, increasing the risk of infections and tumors that a healthy immune system would normally fend off.

What are the two types of HIV and which is more common?

There are two types of HIV: HIV-1 and HIV-2. HIV-1 is more commonly associated with AIDS globally, while HIV-2 is rarer and typically found in western Africa and southern Asia.

How does HIV enter and infect cells?

HIV enters cells by binding to the CD4 molecule on the cell membrane via a protein called gp120. It also needs to bind to a co-receptor, either CCR5 or CXCR4, to gain entry into the cell.

What is the significance of the CCR5 co-receptor in HIV infection?

The CCR5 co-receptor is significant because some individuals with genetic mutations in CCR5 have resistance to HIV. This is because HIV cannot attach and enter the cell without the co-receptor.

How does HIV replicate within the host cell?

HIV is a retrovirus that injects its single-stranded RNA into the host cell. It uses an enzyme called reverse transcriptase to transcribe this RNA into proviral DNA, which is then integrated into the host's DNA. When the immune cell is activated, it inadvertently transcribes and translates new HIV viruses.

What is the difference between the acute and chronic phases of HIV infection?

During the acute phase, there is a rapid increase in viral replication leading to flu-like symptoms. In the chronic phase, the immune system is steadily weakened as HIV continues to replicate, leading to a slow decline in T cell counts and an increase in viral load.

What is the significance of the X4 strain of HIV?

The X4 strain of HIV targets the CXCR4 coreceptor, which is primarily found on T-cells. It can lead to a more aggressive destruction of CD4 T cells, potentially accelerating the progression to AIDS.

How does HIV progress to AIDS?

HIV progresses to AIDS when the immune system becomes severely compromised, typically when T cell counts fall below 200 cells/mm3. At this stage, the body is vulnerable to opportunistic infections and certain cancers.

What are the most common modes of HIV transmission?

The most common modes of HIV transmission are sexual intercourse, intravenous drug use, and mother-to-child transmission. Less common modes include accidental needlesticks and use of blood products.

What are the different types of HIV tests available?

HIV tests include antibody tests, antibody/antigen tests, and RNA/DNA tests. The antibody/antigen test is recommended for screening due to its ability to identify early infection.

How is HIV treated, and what is the goal of treatment?

HIV is treated with antiretroviral therapy (ART), which is a combination of medicines that slow down HIV replication, allowing the immune system to recover and fight off infections more effectively.