Topic 2C - Year 1 - Cells and the Immune System - HIV and Viruses Flashcards
What does HIV stand for ?
HIV stands for human immunodeficiency virus
What can HIV progress to?
HIV can progress to AIDS which is acquired immune deficiency syndrome
Which type of cell acts as the host to the HIV virus?
T helper cells are the host of the HIV virus.
Why is the infection of T helper cells a problem?
T helper cells play a major role in coordinating and immune response , they release chemical signals which activate T cytotoxic cells and phagocytes as well as B cells . Without T helper cells the immune system cannot have an effective response to the invasion a foreign antigen.
When does HIV progress to AIDS?
HIV progresses to aids when the number of T helper cells that are not infected becomes critically low.
What happens when you become infected with HIV?
When you become infected with HIV , the HIV replicates rapidly and a person may experience flu like symptoms.
What is the latency period?
The latency period is the period during which a person is infected with HIV but won’t experience any symptoms. the latency period can last for years.
When do people with HIV start to be classed as having AIDS?
People with HIV begin to be classed as having AIDS when symptoms of their failing immune system begin to show (high susceptibility to infection and inability to overcome this basic infection) or when their T helper cell levels drop bellow a certain level.
Explain the structure of HIV
The virus particle has a spherical structure . The virus has a core which contains RNA and a protein known as reverse transcriptase which is needed for viral replication. The virus has a outer coating of protein called a capsid and an extra outer layer known as an envelope which s stolen from the cell membrane of a pervious host cell. Sticking out from the membrane are attachment proteins . The attachment proteins help HIV attach to the host T helper cell.
How does HIV replicate ?
the attachment proteins on the envelope of the HIV virus attach to receptor molecules on the surface membrane of the host cell (T helper cell)
The capsid is released into the T helper cell where it removes its protein coat releasing its RNA into the T helper cells cytoplasm.
Inside of the cell reverse transcriptase is used to make a complimentary strand of DNA from the viral RNA template.
from this strand of DNA ,double stranded DNA is made and inserted into the human DNA.
Host cell enzymes are used to make viral proteins from the viral DNA found in the human DNA.
The viral proteins are assembled into new viruses and bud from the cell and go on to infect other cells.
How do antibiotics kill bacteria?
Antibiotics kill bacteria by interfering with their metabolic reactions , they target bacterial enzymes and ribosomes used in these reactions.
Why cant antibiotics be used to treat viruses?
Antibiotics target bacterial enzymes and ribosomes in order overcome a disease Burt virsuses don’t have their own ribosomes or enzymes so use the host cell to manufacture their proteins , antibiotics can not inhibit these because they don’t target human processes when trying to stop metabolic reactions.
What can be taken to slow down the progression of HIV?
Antiviral drugs can be taken to slow down the progression of HIV, antiviral drugs are designed to target the ew virus-specific enzymes that exist.
Which test is used to determine weather a person is infected with the HIV virus?
ELISA test
