HIV/AIDS Flashcards
What is the target of HIV
CD4+ T cells, since it uses the CD4 molecule to enter the cell
How is the CD4+ count affected by HIV infection
When HIV first infect the CD4 T cells, many die and the count of CD4 T cells become really low, then again the rise when the IS try to combat the virus. However, after about 3 years the count goes down again when the immune system is almost eliminated. Thereupon The CD4 count just decreases
When is a person considered to have AIDS
AIDS - Acquired immunodeficiency syndrome
When the CD4 count is below 200. At this stage any infection may be lethal
How do HIV treatment work?
ART - Antiretroviral therapy is a combination of inhibitors, aiming to repress the viral replication by targeting different parts of the viral replication:
- Fusion & entry inhibitors
- Integrase inhibitors
- Reverse transcriptas inhibitors
- Protease inhibitors
What is the side effects of early HIV treatment
- Increased blood lipids
- Type 2 diabetes
- Loss of subcutaneous fat
- Kidney dysfunction
When do the HIV transmission occur
HIV is only transmittable when the viral load is high, the window between infection and beginning of treatment. During treatment the viral load is at so low levels that transmission is almost impossible
What are the challenges of preventing HIV infection
- The HIV is carry a very error-prone polymerase, allowing a lot of mutations to occur, therefore activation of the adaptive immune system against an antigen is useless since the virus already mutated its antigens at that time.
- The HIV can be latent in a few resting memory CD4+ cells , it integrate its genome and become invisible to drugs and the immune system. These cells can then allow indefinite persistence patients on treatment and cause a major barrier for treatment.
- HIV constantly activate the immune system that gets exhausted
- HIV start the infection as a chronic inflammation and not like normal infected cells
How do HIV activate the Immune system
- Viremia - the fact that there is a virus present at all times it switches on all the viral response pathways
- lymphopenia - When u kill half of the T cells, the rest have double the amount of nutrient and other factors and thereby become more easily activated
- microbial translocation - since the CD4 cells are depleted the mucosal immune system in the gut is disrupted and the gut becomes leaky, constant entry of viral and microbial agents in ours circulation inducing a chronic low-level inflammation
What is the result of a chronic immune activation
- Constant production of immune mediators - tissue damage and symptoms
- Activated B and T cells become more sensitive to “activation-induced” apoptosis
- Activation induced negative feedback mechanisms - PD1, CTLA4 –> leading to decreased functionality and maintenance!
What is the difference between the natural host and unnatural host of HIV
The natural host, gets the similar symptoms but for a chronic infection; the CD4 count doesn’t drop, there isn’t any microbial translocation
How do HIV take advantage of the chronic inflammation it causes
HIV infects and replicates within activated cells, therefore the virus take advantage of the chronic infection causing T cell constant activation
How is the B cell affected in HIV
HIV doesn’t affect B cells directly, however there is some activation against the virus since there is a present viremia. Although, no normal Ab is produced and all the memory B cells are depleted.
Who is more susceptible to HIV infection
HIV infect immune cells in the mucosa!
Women are more susceptible than hetero-men due to women having a larger mucosal layer in their genitals. Also, the fact that the sperm stays for a longer time in women
Men that had a circumsision are less susceptible since they decrease their mucosal membrane
Homo-men are the most susceptible since their is most CD4+ cells in the mucosal membrane in the anal and also the fact that the sperm stays in women
