HIV and AIDS Flashcards
Describe the structure of HIV?
A core that contains the genetic material and reverse transcriptase. An outer coating of protein called a capsid and an extra outer layer called an envelope, which is a membrane made from the membrane of their previous host cell. They also have attachment proteins sticking out from the envelope that help them attach to their host helper T-cell.
How does HIV replicate?
The attachment proteins on the virus surface bind to receptors on the surface of the helper T cell. The envelope fuses with helper T cell membrane and the capsid is released into the cell where it releases viral RNA and reverse transcriptase. The reverse transcriptase makes DNA from the HIV RNA template. The DNA is inserted into the host cell’s DNA, which gets replicated when the host cell replicates, the host cell enzymes are used to make viral proteins from the viral DNA within the human DNA and the viral proteins are assembled into new viruses, which bud from the cell and go on to infect other cells.
When is somebody classed as having AIDS?
When their helper T cells drop below a certain level or symptoms of their failing immune system start to appear.
Why don’t antibiotics work against viruses?
Antibiotics kill bacteria by interfering with their metabolic reactions, they target the bacterial enzymes and ribosomes involved in these reactions. The antibiotics are designed to only target bacterial enzymes and ribosomes not human ones. As viruses don’t have their own and use their host cells enzymes and ribosomes the antibiotics can’t inhibit them.
What can be done help somebody with HIV as there is no cure?
Antiviral drugs can target virus-specific enzymes like reverse transcriptase as human cells don’t use these enzymes so the drug can be designed to inhibit it. They don’t cure HIV but can slow down its progression.
What is the best way to control HIV?
By reducing the spread, HIV is spread by the exchange of bodily fluids, like unprotected sexual intercourse and sharing of needles.
How can an ELISA test be used to test for HIV?
A HIV antigen is bound to the bottom of a well. A sample of the patient’s blood plasma is added to the well. If there are any antibodies with a complementary shaped binding site to the antigens, they will bind to the HIV antigen. The well is then washed to remove any unbound antibodies. A second antibody with an enzyme attached is added, the second antibody can bind to the HIV-specific antibody. The well is then washed again. A solution is then added that contains a substrate, which reacts with the enzyme and causes a colour change. If there is a colour change the patient has the HIV-specific antibodies in their blood and is infected with HIV.
