HIV and AIDS Flashcards
Describe the basics of HIV & AIDS?
- HIV is a blood borne virus with over 30 million affected worldwide
- It starts off as human immunodeficiency virus but if left untreated it causes acquired immunodeficancy syndrome
What are the risk factors for HIV?
- Mainly men have sex with men
- Black african population
What are the transmission routes for HIV?
- Sexual intercourse
- Vertical transmission
- Sharing needles
- Needlestick injury
- Blood transfusion
- Organ transplant
What are the basic epidemiology behind HIV-1 and HIV-2
HIV-1 - Is the most prominent type of HIV, accouts for around 95% of all HIV, Located all over the world incluidng europe
HIV-2 - Concentrated mainly in western Africa, dosent progress as fast as HIV-1 but can still lead to AID’s
Describe the subtypes of HIV-1?
There is an M & N group of HIV
M subtype is responsible for epidemic
Within the M subtype there are mulitple substypres A,B,C, D, F, G, J, K
Describe the pathology behind HIV
HIV is a lentivirus which belongs to a group of viruses called retroviruses
- The virus is incorporated into a host cell, whereby, the viral enzyme transcriptase will begin transcription of the RNA to DNA. Then, the viral enzyme integrase will integrate the DNA into the host’s.
- Cause slow infections with long incubation periods
- RNA to DNA using reverse transcriptase
Describe the virology behind HIV and how it interacts with the host?
- On the exterior of the HIV virus there are 2 envelope proteins, gp120 and gp41
- The gp120 protrudes from the surface and interacts with CD4 receptors on the host cell
- The gp41 is embedded in the envelope and mediates fusion of the viral envlope with the host cell membrane at the time of the infection
What proteins servers as an important serological marker for the infection?
Antibodies against p24 do not neutralise HIV infectivity, but they do serve as important serological markers
What happens when the gp120 protien interacts with the surface of the envelope?
- The gp120 protein also interacts with a second protein on the host cell surface, one of the chemokine receptors (CCR5 or CXCR4)
- These are essential proteins for entry of HIV into CD4 positive cells
What happens when HIV makes in into the host cell?
Once in the host cell, the HIV uses reverse transcriptase to convert its genetic material from RNA to DNA. This allows its to enter into the host cell nucleus, and once inside the nucleus, via the enzyme integrase, the HIV DNA integrates with the host cell DNA.
Once that is achieved, through transcription and translation, the virus replicates in the host cell.
The HIV enzyme protease then cuts up the long chains of HIV proteins, which combine with HIV RNA to form a new virus.
This is followed by budding of the newly made HIV which leaves the host cell to infect more CD4 receptor cells.
Describe the Diagnostic window?
- During the first month after infection, antibody tests may be negative
- The acute diagnosis of HIV might not be detectable
Describe the tests used to detect the HIV virus?
Length of window period varies between individuals
- 4th generation ELISA assays allow simultaneous detection of antibody and antigen
- 4th
Describe the use of viral load?
- Detection of HIV RNA range
- Used to monitor the effectiveness of the HIV treatment
- The main use of the HIV viral load is to monitor the effectivness of the anti-reteroviral therapy
HIV resistance testing
- Sequencing of the polymerase and protease genes
- Identification of the specific mutations that confer resistance to antiretroviral drugs
What other tests are used?
Tropsim testing - Which co-receptor does the virus use to enter the CD4 cells, required before using a
