Types Of Immunities Flashcards
What is active immunity?
The body makes antibodies after being exposed to an antigen
What is natural and artificial active immunity?
Natural-become immune after catching disease
Artificial-become immune after being given the vaccination containing weaked pathogen
Long term as memory cells are produced
What is passive immunity?
The body is given antibodies that have been made by a different organism
-natural:a baby can get antibodies from mother through placenta or breast milk
Artificial:you are injected with antibodies or antitoxins
Which are short term and no immune response is involved and memory cells
What are the problems with passive immunity?
Protection is temporary and only last few month after birth- as they will be broken down in the liver and spleen and no memory cells are formed
What is herd immunity?
When a population can be protected from a certain virus if a threshold of vaccination is reached.
Describe the structure of HIV retrovirus.
RNA which can DNA in others
Capsid
Reverse transcriptase enzyme (turns RNA into DNA) which is a retrovirus
Glycoprotein
Lipid envelope
What does retrovirus mean?
A virus that uses RNA as its genomic material.
State the basis of HIV infection
-The human immunodeficiency viruses are 2 species of lentivirus (a subgroup of retrovirus) that infect humans
-it works by infecting helper T cells
-virus replicates in T cell using cellular machinery,eventually the cells is lysed (destroying cell)
-and over time the T cells decrease and causes AIDS(acquired immunodeficiency syndrome)
-lowering body’s defence and cancers to thrive in the body
-HIV positive people can be diagnosed through a low white blood cell count or through a test to check a presence of viral DNA
How does HIV replicate inside of the T helper cells?
1-glycoprotein binds to CD4 receptors on t helper cells ,allows the glycoprotein surrounding the virus to fuse with the
t helper cell membrane.
2-the capsid is released into cell where it releases the RNA and reverse transcriptase
3-reverse transcriptase is used to make DNA from RNA from HIV
4-DNA is inserted into cells DNA which gets replicated when cells replicate.
5-that DNA is used to make HIV RNA and proteins at host ribosomes, ensures the replication and assembly of new viral particles, ultimately leading to the infection and destruction of CD4+ T cells.
6-virus particles are assembled which bud off from the cell membrane and go to infect other cells
How is HIV transmitted?
Having unprotected sex with infected person
-close contact with infected person through the blood(share of needles)
-use infected blood in blood transfusion
-mother to child
From placenta or milk
And baby must be tested at 18 months as it takes time for the virus to replicate and be detectable.
When do people get AIDS?and symptoms and how long to catch HIV symptoms?
-When their number of helper T cells reach a critical level.
-minor infections of mucosal membranes (mucus is not made so can’t filter out materials that you breathe in through your nose, such as dust and microorganisms)
and reccuring respiratory infections cause by a lower than normal number of T helper cells
-Takes 10 years for HIV patient to develop symptoms of AIDS
Because the Virus can remain inactive as DNA in host cells
Treatment of AIDS
-Antiretroviral drugs available after 6 months can slow down the replication of the virus in the body by blocking reverse transcriptase enzyme
-But there is no cure to HIV
-They reduce viral load in body to an “ undetectable” level so patients can not pass on HIV to other people.
State the prevention treatment against HIV
Pre-exposure prophylaxis
-where HIV negative individuals can take anti-retroviral drugs before coming into contact with HIV to reduce Rick of being infected
But it has not been accepted around the world
Why are antibiotics ineffective against viral diseases
Viruses don’t have a cell wall made of murein
Inside cell so antibiotics can’t reach them
How do antibiotics kill bacterial pathogens?
They prevent bacteria from making cell walls
-cells are made of murein (protein of E.coli) and stops the cells from bursting due to water(osmosis)
-antibiotics weaken the cell walls by inhibiting enzymes that synthesise the peptide cross linkage in cell walls
-when water moves in by osmosis the cells burst and bacterium dies.
