Vaccines, Disease & Monoclonal Antibodies

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Vaccines

Vaccines introduce pathogenic antigens into the body, triggering a specific immune response and antibody release by plasma cells.
They may contain weakened pathogens, antigens, or genetic material coding for antigens.
Vaccination produces active immunity because it causes memory cells to form.
On later exposure, memory cells give a faster, stronger secondary response that eliminates the pathogen before symptoms develop.
Vaccines protect both individuals and populations by triggering immunity.

Herd Immunity

Herd immunity occurs when enough people are vaccinated to stop the spread of infection.
It protects unvaccinated individuals, such as babies or those with weakened immune systems.
The more infectious a disease, the higher the proportion of the population that must be vaccinated.
If vaccination rates drop below the threshold, herd immunity is lost (e.g. measles outbreak in Swansea, 2012).
Herd immunity reduces the number of susceptible individuals and halts the spread of infection.

Active & Passive Immunity

Active immunity occurs when the immune system is stimulated by an antigen to produce antibodies and memory cells.
It can be gained naturally from an infection or artificially from a vaccination.
Active immunity provides long-term protection due to memory cell formation.
Passive immunity is when a person receives ready-made antibodies without producing them.
No immune response is triggered, so no memory cells form and protection is short-term.
Passive immunity is useful when immediate protection is needed, e.g. tetanus antitoxin.
Passive immunity can be artificial (injection of antibodies) or natural (via placenta or breast milk).

HIV Structure and Replication

HIV is a retrovirus with RNA as its genetic material.
It contains reverse transcriptase, which converts viral RNA into DNA.
It has a protein coat (capsid), a lipid envelope derived from the host cell membrane, and attachment proteins.
HIV is transmitted by direct exchange of body fluids, e.g. during sexual intercourse or blood donation.
Replication: viral RNA enters the helper T cell; reverse transcriptase makes a DNA copy; the DNA inserts into the host chromosomes; viral proteins are produced; new HIV particles are assembled and released, killing the helper T cell.
New HIV particles infect other helper T cells, gradually reducing their number.

AIDS

HIV infection often causes mild flu-like symptoms initially, followed by a latent period with no obvious symptoms.
Over time, HIV becomes active and destroys helper T cells.
Fewer helper T cells means B cells are no longer activated, so no antibodies are produced.
This weakens the specific immune response, reducing the ability to fight infections.
Eventually the person develops AIDS (acquired immune deficiency syndrome).
Opportunistic infections (e.g. TB) can then occur and may be fatal.
There is no cure for AIDS, but antiviral drugs can slow virus replication; with treatment, HIV-positive individuals can have a normal life expectancy.
Antibiotics are ineffective against viruses like HIV because viruses lack metabolism and the cellular structures targeted by antibiotics.

Monoclonal Antibodies

Monoclonal antibodies (mAbs) are identical antibodies from a single B cell clone.
They are highly specific and bind to one particular antigen.
In drug delivery, mAbs can be designed to bind only to specific cells, e.g. cancer cells, carrying a therapeutic drug directly to them.
This increases effectiveness and reduces damage to healthy cells.
In medical diagnosis, mAbs detect the presence and location of specific antigens and are often labelled with a radioactive, fluorescent or enzyme marker.
Common uses include pregnancy tests (hCG), infection detection (e.g. HIV, Streptococcus), cancer screening and locating blood clots/tumours.

ELISA

ELISA (Enzyme-Linked Immunosorbent Assay) uses antibodies to detect the presence and quantity of a specific antigen or antibody in a sample.
An enzyme is attached to antibodies; when the enzyme reacts with a substrate, a coloured product forms.
A colour change indicates that the antigen or antibody of interest is present.
Direct ELISA uses a single antibody complementary to the antigen being tested for.
Indirect ELISA uses two antibodies: primary and secondary.
In indirect ELISA for HIV: HIV antigens are fixed to the well; patient plasma is added; HIV-specific antibodies bind; wells are washed; enzyme-linked secondary antibodies are added; another wash removes unbound antibodies; substrate is added; a colour change indicates the patient has HIV-specific antibodies.

Ethical Issues with Vaccines & Monoclonal Antibodies

Vaccines are first tested on animals, which some view as unethical; animal-derived substances may also be used in production.
Human testing carries risks (e.g. side effects or false sense of protection); volunteers may be vulnerable if motivated by payment.
Some avoid vaccines due to small risk of side effects; herd immunity protects them, which some argue is unfair.
Concerns over parents refusing vaccines for children, potentially putting them at risk.
During epidemics, questions arise over priority groups (e.g. elderly or healthcare workers during COVID-19) and global inequality in access.
Monoclonal antibodies: mice are used to produce mAbs, raising animal welfare concerns.
mAbs may have serious side effects; informed consent is essential, and trials may involve vulnerable participants.
mAb treatments are often expensive, raising concerns about fair access, especially in lower-income countries.

Evaluating Studies: The MMR Vaccine Example

The MMR vaccine protects against measles, mumps, and rubella.
A 1998 study based on just 12 children suggested a link between the vaccine and autism.
It was later revealed that one author had a conflict of interest (consulting for parents suing vaccine manufacturers).
The study was discredited and retracted, but caused a drop in vaccination rates.
A 2005 study of 30,000 children in Japan showed autism rates continued to increase even after the MMR vaccine was stopped.
This suggests no link between the MMR vaccine and autism; the large sample size increases confidence in the results.
Key evaluation points: repeatability, reproducibility, validity, large unbiased sample sizes, peer review, replication, and transparency in funding and conflicts of interest.

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1.Which of the following best defines a vaccine?
Easy
- AA preparation containing antigens that stimulates an immune response and the production of memory cells
- BA preparation containing ready-made antibodies that provides immediate protection
- CA drug that kills bacteria by disrupting their metabolism
- DA substance that directly destroys pathogens in the blood
2.What name is given to the level of immunity in a population that stops a disease from spreading?
Easy
- AActive immunity
- BPassive immunity
- CHerd immunity
- DNatural immunity
3.Which of the following is an example of natural passive immunity?
Medium
- AAntibodies passing from mother to foetus across the placenta
- BBeing vaccinated against measles
- CRecovering from a chickenpox infection
- DReceiving an injection of antivenin after a spider bite
4.Which of the following correctly describes a difference between active and passive immunity?
Medium
- AActive immunity produces memory cells, whereas passive immunity does not
- BPassive immunity produces memory cells, whereas active immunity does not
- CActive immunity provides immediate protection, whereas passive immunity takes 1–2 weeks
- DPassive immunity lasts a lifetime, whereas active immunity is short-term
5.Which enzyme does HIV use to convert its RNA into DNA?
Medium
- AReverse transcriptase
- BDNA polymerase
- CRNA polymerase
- DLigase
6.Why are antibiotics ineffective against viruses such as HIV?
Medium
- AViruses lack the cellular structures and metabolism that antibiotics target
- BViruses are too large for antibiotics to penetrate
- CViruses have a protein coat that antibiotics cannot break down
- DViruses replicate too quickly for antibiotics to act
7.What is a monoclonal antibody?
Medium
- AAn antibody produced by a single clone of B cells that binds to one specific antigen
- BA mixture of antibodies that bind to many different antigens
- CAn antibody produced by the body in response to a vaccine
- DA type of white blood cell that engulfs pathogens
8.In an indirect ELISA test for HIV, what is the purpose of washing the well after adding the patient's blood plasma?
Medium
- ATo remove unbound antibodies
- BTo remove bound antibodies
- CTo add the substrate
- DTo attach the enzyme to the antibodies

Plus de questions

9.Which of the following are ethical concerns associated with the use of vaccines? (select all that apply)
Medium
- AUse of animals in testing and production
- BRisk of side effects
- CGlobal inequality in access to vaccines
- DVaccines cause autism
- EExploitation of volunteers motivated by payment
10.Which of the following statements about HIV and AIDS are correct? (select all that apply)
Hard
- AHIV infects and destroys helper T cells
- BAIDS is caused by HIV
- CHIV can be transmitted by direct exchange of body fluids
- DAntibiotics can cure HIV
- EA person can be HIV positive without having AIDS
11.Herd immunity protects unvaccinated individuals, such as babies or those with weakened immune systems.
Easy
True or false?
12.Passive immunity results in the formation of memory cells.
Easy
True or false?
13.Monoclonal antibodies are highly specific and bind to one particular antigen.
Medium
True or false?
14.Match each type of immunity to its correct example.
Medium
- Natural passive
- Artificial passive
- Natural active
- Artificial active
- Antibodies across the placenta
- Injection of antivenin
- Recovering from an infection
- Being vaccinated
15.Place the stages of HIV replication in the correct order.
Medium
- Viral RNA enters the cell
- Reverse transcriptase produces a DNA copy of viral RNA
- The DNA copy is inserted into the host cell's chromosomes
- HIV proteins are produced from viral DNA
- New HIV particles are released, killing the helper T cell
16.A patient is given an intravenous drip of a monoclonal antibody rather than a tablet. Why is the drip used?
Hard
- AThe monoclonal antibody would be digested in the stomach and not reach the target cells
- BThe monoclonal antibody is too large to be absorbed in the small intestine
- CThe monoclonal antibody would be destroyed by the immune system if swallowed
- DThe monoclonal antibody is not soluble in water
17.Why might a patient experience an immune response to a monoclonal antibody treatment?
Hard
- AThe monoclonal antibody is a foreign protein and acts as an antigen
- BThe monoclonal antibody is recognised as a pathogen by the patient's memory cells
- CThe monoclonal antibody is made of RNA and triggers an immune response
- DThe monoclonal antibody is too large and causes an allergic reaction
18.A scientist claims a new vaccine causes a side effect. Which of the following would best evaluate the validity of this claim?
Challenge
- ACheck whether the study was large, unbiased, peer-reviewed and replicated
- BCheck whether the scientist is well-known
- CCheck whether the vaccine is used in other countries
- DCheck whether the side effect is mentioned on social media
19.Which of the following can be components of a vaccine? (select all that apply)
Medium
- AWeakened forms of the pathogen
- BAntigens from the pathogen
- CGenetic material that codes for the pathogen's antigens
- DReady-made antibodies against the pathogen
- ELive, unattenuated pathogen at full virulence
20.Match each feature of immunity to the type of immunity it describes.
Medium
- Antibodies produced by the body
- Antibodies not produced by the body
- Memory cells present
- Antibodies appear in the blood 1–2 weeks after exposure
- Antibodies appear in the blood immediately
- Active immunity
- Passive immunity
21.Place the stages of HIV replication inside a helper T cell in the correct order.
Medium
- Viral RNA enters the cell
- Reverse transcriptase produces a DNA copy of the viral RNA
- The DNA copy is inserted into the cell's chromosomes
- HIV proteins are produced from the viral DNA
- New HIV particles are released, killing the helper T cell
22.Which of the following statements about passive immunity are correct? (select all that apply)
Medium
- AIt provides immediate protection
- BIt involves the transfer of ready-made antibodies
- CIt results in the formation of memory cells
- DIt can be gained naturally across the placenta
- EIt provides long-term immunity
23.Which of the following are ethical issues associated with the use of monoclonal antibodies? (select all that apply)
Hard
- AMice are used to produce the antibodies, which may cause suffering
- BTreatments are often expensive, raising concerns about fair access
- CInformed consent is needed because patients must understand the risks
- DMonoclonal antibodies are identical antibodies from a single B cell clone
- ETrials may involve vulnerable participants, such as those who are severely ill
24.In an indirect ELISA test for HIV, a substrate is added after the secondary antibody. What indicates a positive result?
Medium
- AA colour change occurs because the enzyme attached to the secondary antibody reacts with the substrate
- BThe well becomes colourless because the HIV antigens have been broken down
- CA precipitate forms because the primary antibodies clump together
- DThe well remains unchanged because the enzyme is not present
25.A person can be HIV positive but not yet have developed symptoms of AIDS.
Easy
True or false?
26.Antibiotics are effective against HIV because they disrupt the viral capsid.
Medium
True or false?
27.A patient is given a vaccine that contains only the antigen of a pathogen, not the whole pathogen. Which statement best explains why this vaccine is still able to provide protection against the disease?
Medium
- AThe antigen triggers an immune response that produces memory cells, so a future infection leads to a faster, stronger secondary response.
- BThe antigen directly kills the pathogen by disrupting its metabolism.
- CThe antigen provides ready-made antibodies that neutralise the pathogen immediately.
- DThe antigen causes the pathogen to mutate into a harmless form.
28.In a population, the proportion of people vaccinated against a highly infectious disease falls below the herd immunity threshold. Which of the following is the most likely immediate consequence?
Medium
- AThe disease can spread more easily because there are more susceptible individuals.
- BVaccinated individuals lose their memory cells and become susceptible again.
- CThe pathogen becomes less infectious because fewer people are vaccinated.
- DUnvaccinated individuals develop passive immunity from the vaccinated individuals.
29.A patient is injected with antivenin containing antibodies against a spider toxin. Which of the following correctly describes the type of immunity gained and a key feature of this immunity?
Medium
- APassive immunity; no memory cells are produced so protection is short-term.
- BActive immunity; memory cells are produced so protection is long-term.
- CPassive immunity; memory cells are produced so protection is long-term.
- DActive immunity; antibodies are produced by the patient's own plasma cells.
30.A researcher is testing a new vaccine. They give the vaccine to 10 volunteers and 3 weeks later measure antibody concentration in their blood. The results show a mean increase in antibody concentration. Which of the following is the most significant weakness of this study?
Hard
- AThe sample size is too small, so the results may not be reliable or generalisable.
- BThe antibody concentration was measured too soon after vaccination.
- CThe vaccine was not tested on animals first.
- DThe volunteers were not paid for their participation.
31.In an indirect ELISA test for HIV, a patient's blood plasma is added to a well coated with HIV antigens. After washing, a secondary antibody with an attached enzyme is added, followed by another wash and then a substrate. A colour change is observed. What does this result indicate?
Medium
- AThe patient has antibodies against HIV in their blood.
- BThe patient is currently infected with HIV and has the virus in their blood.
- CThe patient has been vaccinated against HIV.
- DThe patient has an active HIV infection and is showing symptoms of AIDS.
32.Monoclonal antibodies can be used to deliver a radioactive substance to cancer cells. Which of the following best explains why this is more effective than injecting the radioactive substance alone?
Medium
- AThe monoclonal antibody binds only to cancer cells, so the radioactive substance is concentrated at the tumour and damages fewer healthy cells.
- BThe monoclonal antibody neutralises the radioactive substance so it does not harm healthy cells.
- CThe monoclonal antibody makes the cancer cells more sensitive to radiation.
- DThe monoclonal antibody prevents the radioactive substance from being excreted by the kidneys.
33.Which of the following statements about the structure of HIV are correct? (select all that apply)
Medium
- AHIV contains RNA as its genetic material.
- BHIV has a protein coat called a capsid.
- CHIV has a lipid envelope derived from the host cell membrane.
- DHIV contains reverse transcriptase enzyme.
- EHIV contains DNA as its genetic material.
34.A new vaccine is being developed against a bacterial disease. Which of the following are ethical issues that should be considered before widespread use? (select all that apply)
Hard
- AThe vaccine may be tested on animals, which raises animal welfare concerns.
- BTrial participants may be vulnerable if motivated by payment.
- CThere may be unequal access to the vaccine between wealthy and poorer countries.
- DVaccinated individuals may develop memory cells against the pathogen.
- ESome individuals may experience side effects from the vaccine.
35.A person can be infected with HIV but not yet show symptoms of AIDS.
Easy
True or false?
36.A study in Japan followed 30,000 children from 1988 to 1996. The MMR vaccine was introduced in 1989 and stopped in 1993. The number of children diagnosed with autism by age 7 continued to increase even after the vaccine was stopped. What is the most valid conclusion from this data?
Hard
- AThere is no link between the MMR vaccine and autism.
- BThe MMR vaccine causes autism but only after a delay.
- CThe MMR vaccine prevents autism.
- DThe data is unreliable because the sample size is too small.
37.A new monoclonal antibody treatment for cancer is being tested. Some patients develop an immune response to the treatment. Which of the following best explains why this occurs?
Challenge
- AThe monoclonal antibody is a foreign protein, so the patient's immune system may recognise it as an antigen and produce antibodies against it.
- BThe monoclonal antibody is recognised as a cancer cell and attacked by the immune system.
- CThe monoclonal antibody causes the cancer cells to release antigens that trigger an immune response.
- DThe monoclonal antibody is too large to enter the cells, so it accumulates in the blood and triggers an immune response.
38.A patient with a severe bacterial infection is given a monoclonal antibody that binds to a bacterial toxin. Which of the following best explains why this treatment provides immediate protection?
Hard
- AThe antibodies bind to and neutralise the toxin directly, without needing the patient's immune system to respond.
- BThe antibodies stimulate the patient's plasma cells to produce more antibodies.
- CThe antibodies activate memory cells to produce a secondary response.
- DThe antibodies directly kill the bacteria by disrupting their metabolism.
39.Which of the following are reasons why a vaccine may not provide immediate protection against a disease? (select all that apply)
Medium
- AIt takes time for the immune system to produce antibodies and memory cells.
- BThe vaccine contains antigens that trigger a primary immune response.
- CThe vaccine may not contain live pathogens.
- DThe vaccine may be given as a course of multiple doses.
- EThe vaccine causes memory cells to be produced.
40.Monoclonal antibodies used in pregnancy tests are labelled with an enzyme that causes a colour change when it reacts with a substrate.
Medium
True or false?
41.Complete the sentence about vaccination.
Easy
Vaccines introduce pathogenic ____ into the body, triggering a specific immune response.
42.Name the type of immunity gained from an injection of antibodies.
Medium
An injection of antibodies provides ____ immunity.
43.Name the enzyme that HIV uses to convert RNA into DNA.
Medium
44.A patient has a mean antibody concentration of 20 arbitrary units before vaccination. After vaccination, it rises to 65. Calculate the percentage increase.
Medium
45.Complete the sentences about the structure and replication of HIV.
Medium
HIV is a retrovirus, meaning its genetic material is ____. The enzyme ____ converts this into DNA, which is then inserted into the host cell's chromosomes.
46.In a study of a new vaccine, the mean antibody concentration was 25 arbitrary units 3 weeks after the first dose and 90 arbitrary units 3 weeks after the second dose. Calculate the percentage increase in mean antibody concentration between these two samples. Give your answer to the nearest whole number.
Medium
47.Name the type of immunity gained when a person receives an injection of ready-made antibodies.
Easy
48.Complete the sentence about the indirect ELISA test for HIV.
Medium
After adding the patient's blood plasma to the well, the well is washed to remove ____ antibodies.
49.Complete the sentence about HIV replication.
Medium
HIV uses the enzyme ____ to convert its RNA into DNA.
50.In a study of a new vaccine, the mean antibody concentration was 40 arbitrary units 3 weeks after the first dose and 120 arbitrary units 3 weeks after the second dose. Calculate the percentage increase in mean antibody concentration between the two samples.
Medium
51.In a population, the percentage of children vaccinated against measles fell from 92% in 1990 to 80% in 1994. Calculate the percentage decrease in children vaccinated between 1990 and 1994.
Medium
52.Name the enzyme that HIV uses to convert its RNA into DNA.
Medium
53.Describe how vaccination can lead to protection against pulmonary tuberculosis.
Hard
54.Explain why a second dose (booster) of a vaccine causes the concentration of antibodies in the blood to increase immediately.
Hard
55.Explain why monoclonal antibodies are described as highly specific and why this makes them useful in medical diagnosis.
Hard
56.A patient has a mean antibody concentration of 20 arbitrary units before vaccination. After vaccination, it rises to 65. Calculate the percentage increase.
Medium
- A248 %
- B202 %
- C225 %
- D271 %
57.In a study of a new vaccine, the mean antibody concentration was 25 arbitrary units 3 weeks after the first dose and 90 arbitrary units 3 weeks after the second dose. Calculate the percentage increase in mean antibody concentration between these two samples. Give your answer to the nearest whole number.
Medium
- A260 %
- B234 %
- C286 %
- D312 %
58.In a study of a new vaccine, the mean antibody concentration was 40 arbitrary units 3 weeks after the first dose and 120 arbitrary units 3 weeks after the second dose. Calculate the percentage increase in mean antibody concentration between the two samples.
Medium
- A200 %
- B220 %
- C180 %
- D240 %
59.In a population, the percentage of children vaccinated against measles fell from 92% in 1990 to 80% in 1994. Calculate the percentage decrease in children vaccinated between 1990 and 1994.
Medium
- A14 %
- B13 %
- C15 %
- D12 %

Notes de révision

## Vaccines - Introduce **pathogenic antigens** → specific immune response → plasma cells release antibodies. - May contain weakened pathogen, antigens, or genetic material coding for antigens. - Produce **active immunity**: memory cells formed → faster, stronger **secondary response** on re-exposure → pathogen eliminated before symptoms. - **Herd immunity**: enough people vaccinated to stop spread; protects unvaccinated (babies, weakened immune systems). More infectious disease → higher proportion must be vaccinated. If vaccination rates drop below threshold, herd immunity lost (e.g. measles outbreak Swansea 2012). ## Active & Passive Immunity | Feature | Active | Passive | |---|---|---| | Antibody production | produced by body | not produced by body | | Time before antibodies appear | 1–2 weeks | immediate | | Memory cells | yes | no | | Induced by | natural exposure or artificial vaccination | natural (placenta/colostrum) or artificial (injected antibodies) | - Active = long-term (memory cells). Passive = short-term, no memory cells; used when immediate protection needed (e.g. tetanus antitoxin). ## HIV - **Retrovirus**: genetic material is RNA. - Structure: RNA, **reverse transcriptase**, capsid (protein coat), lipid envelope (from host helper T cell membrane), attachment proteins. - Transmission: direct exchange of body fluids (sexual intercourse, blood donation). - Replication: viral RNA enters helper T cell → reverse transcriptase makes DNA copy → inserted into host chromosomes → viral proteins built → thousands of new HIV particles released, killing helper T cell. - Gradually reduces helper T cells → B cells not activated → no antibodies → decreased ability to fight infections → **AIDS** (acquired immune deficiency syndrome). - HIV positive ≠ AIDS; latent period with no obvious symptoms. - No cure; antiviral drugs slow replication. Antibiotics ineffective against viruses (lack metabolism/cellular structures targeted). ## Monoclonal Antibodies - **mAbs**: identical antibodies from a single B cell clone; highly specific, bind one particular antigen. - Uses: drug delivery (bind only to specific cells e.g. cancer, carry therapeutic drug → increases effectiveness, reduces damage to healthy cells); medical diagnosis (detect antigens, labelled with radioactive/fluorescent/enzyme marker). - Examples: pregnancy tests (hCG), infection detection (HIV, Streptococcus), cancer screening, locating blood clots/tumours. ## Ethical Issues - Vaccines: animal testing; human trials (risks, exploitation); side effects; parents refusing for children; epidemic priority groups; global inequality. - mAbs: mice used (suffering); human use (side effects, informed consent, vulnerable participants); expensive → fair access concerns. - Claims must be backed by repeatable, reproducible studies; critical evaluation ensures reliable, valid, not misleading findings. - **MMR example**: 1998 study (12 children) suggested autism link; conflict of interest, discredited, retracted → drop in vaccination. 2005 study (30,000 children, Japan) showed autism increased even after MMR stopped → no link; large sample size increases confidence. ## ELISA - **ELISA** (Enzyme-Linked Immunosorbent Assay) uses antibodies to detect presence/quantity of specific antigen or antibody. - Enzyme attached to antibody → reacts with substrate → coloured product → colour change indicates target present. - Direct ELISA: single antibody. Indirect ELISA: two antibodies (primary and secondary). - Indirect ELISA for HIV: HIV antigens fixed → patient plasma added (primary antibodies bind) → wash → secondary antibodies with enzyme added → wash (avoids false positive) → substrate added → colour change = HIV-specific antibodies present.

Vaccine: Introduces pathogenic antigens into the body, triggering a specific immune response resulting in antibody release by plasma cells.
Herd immunity: Occurs when enough people are vaccinated to stop the spread of infection, protecting unvaccinated individuals.
Active immunity: Occurs when the immune system is stimulated by an antigen to produce antibodies and memory cells; provides long-term immunity.
Passive immunity: When a person receives ready-made antibodies without producing them; no memory cells formed, so protection is short-term.
Memory cells: Cells produced during active immunity that give a faster and stronger secondary response on re-exposure to the same antigen.
HIV: A retrovirus with RNA genetic material; infects helper T cells, gradually reducing their number and weakening the immune system.
AIDS: Acquired immune deficiency syndrome; develops when HIV damages the immune system so it can no longer respond to pathogens.
Reverse transcriptase: Enzyme that converts viral RNA into DNA, which can then be inserted into the host cell's chromosomes.
Monoclonal antibodies (mAbs): Identical antibodies from a single B cell clone; highly specific and bind to one particular antigen.
ELISA: Enzyme-Linked Immunosorbent Assay; uses antibodies to detect the presence and quantity of a specific antigen or antibody in a sample.

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