Deck 18: Applications of Immune Responses

Question 1

The procedure developed by the Chinese to protect against smallpox was called

A) Oriental poxination.
B) humoral immunity.
C) variolation.
D) naturally acquired immunity.
E) vacciolation.

Answer 1

C

Question 2

Inactivated immunizing agents are prepared by treatment with

A) alcohol.
B) phenol.
C) formalin.
D) histamine.
E) mercury.

Answer 2

C

Question 3

Almost all of the antibodies found in a newborn are

A) the result of infection.
B) the result of passive immunity.
C) self-made.
D) IgM.
E) the result of active immunity.

Answer 3

B

Question 4

Whole agent vaccines may contain

A) viruses.
B) bacteria.
C) toxins.
D) polysaccharides.
E) viruses OR bacteria.

Question 5

Substances that are contained in vaccines to help induce a better immune response are called

A) primary substances.
B) secondary substances.
C) adjuncts.
D) secondary adjuncts.
E) adjuvants.

Question 6

The Salk polio vaccine

A) protects against nervous system and gastrointestinal infection.
B) protects only against gastrointestinal infection.
C) is a subunit vaccine.
D) protects only against nervous system infection.
E) protects against nervous system and gastrointestinal infection AND is a subunit vaccine.

Question 7

The scientist who made variolation safer and more effective was

A) Pasteur.
B) Jenner.
C) Metchnikoff.
D) Fleming.
E) Ehrlich.

Question 8

Herd immunity

A) only occurs in a population in which all individuals are immune.
B) occurs in a population in which a large percentage of the population is immune.
C) only provides protection to those that are already immune.
D) is responsible for dramatic increases in childhood diseases.
E) occurs in a population in which a large percentage of the population is immune AND is responsible for dramatic increases in childhood diseases.

Question 9

The most common adjuvant is

A) ethanol.
B) formalin.
C) aluminum.
D) hydroxide.
E) alum.

Question 10

The virus originally used for vaccination against smallpox is named

A) vaccinia.
B) cowpox.
C) rubella.
D) herpes.
E) polio.

Question 11

The Salk vaccine

A) contains live attenuated virus.
B) contains inactivated virus.
C) contains a portion of the polio virus.
D) occasionally causes disease.
E) is a DNA-based vaccine.

Question 12

Attenuated agents are

A) dead viruses.
B) toxins.
C) weakened but replicating microbes.
D) parts of an organism.
E) weakened, nonreplicating microbes.

Question 13

All of the following are True about the term vaccination EXCEPT it

A) is a general term that would include the process of variolation.
B) was coined by Jenner.
C) was coined by Pasteur and comes from the Latin for cow, variola.
D) comes from the Latin for cow, vacca.
E) was coined by Jenner and comes from the Latin for cow, vacca.

Question 14

A recombinant vaccine is used to protect against

A) hepatitis B.
B) polio.
C) diphtheria.
D) pertussis.
E) influenza.

Question 15

The last case of naturally contracted smallpox occurred in

A) 1900.
B) 1950.
C) 1965.
D) 1977.
E) 1989.

Question 16

Which antibodies cross the placenta and protect the fetus?

A) IgA
B) IgG
C) IgM
D) IgD
E) IgM and IgG

Question 17

All of the following are True about attenuated agents EXCEPT

A) they only induce immunity after several doses.
B) they may cause disease in immunocompromised individuals.
C) they multiply in the body.
D) they may revert or mutate to disease-causing strains.
E) they cause a strong cell-mediated immune response.

Question 18

The practice of deliberately stimulating the immune system is called

A) acquired immunity.
B) vaccination.
C) hypersensitivity.
D) memory immunity.
E) autoimmunity.

Question 19

Toxoids are used in vaccines against

A) Haemophilus influenza type b.
B) diphtheria.
C) herpes simplex type I.
D) polio.
E) diphtheria AND herpes simplex type I.

Question 20

Variolation is a procedure once used to protect against

A) measles.
B) bubonic plague.
C) rabies.
D) smallpox.
E) cowpox.

Question 21

Anti-human IgG antibodies are often used in

A) direct fluorescent antibody tests, radioimmunoassay, AND direct ELISA.
B) complement fixation test, radioimmunoassay, AND Western blotting.
C) radioimmunoassay, indirect ELISA, AND indirect fluorescent antibody tests.
D) indirect fluorescent antibody tests, complement fixation tests, AND Western blotting.
E) indirect ELISA, Western blotting, AND indirect fluorescent antibody tests.

Question 22

Precipitation reactions depend on

A) the antigen having one epitope.
B) the antibody having one epitope.
C) the antigen having two or more epitopes.
D) the antigen having no epitopes.
E) the epitope have one or more antigens.

Question 23

DNA vaccines work by

A) stimulating production of antibodies against DNA.
B) stimulating interferon production.
C) inactivating the host DNA.
D) having the cell use the introduced DNA to make the microbial protein antigen.
E) having the cell use the introduced DNA to make inactivating microbial mRNA.

Question 24

For which of the following childhood diseases is a subunit vaccine recommended?

A) Polio
B) Measles
C) Hepatitis B
D) Pertussis
E) Chickenpox

Question 25

Monoclonal antibodies obtained from a hybridoma provide

A) a large amount of an antibody that is specific for a particular epitope.
B) a single antibody that recognizes many epitopes.
C) many epitopes that recognize a specific antibody.
D) a large number of B cells.
E) a large amount of an antibody that reacts with a wide range of epitopes.

Question 26

If a positive reaction is last observed at a dilution of 1:256, the titer is ________.

A) 128
B) 1/512
C) 1/256
D) 256
E) 512

Question 27

Monoclonal antibodies

A) are usually of different classes.
B) usually recognize several epitopes.
C) have the same variable regions.
D) are always IgE.
E) All of the answer choices are correct.

Question 28

Which type of vaccine has been used in place of inactivated whole cell vaccine?

A) Acellular subunit
B) Whole cell attenuated
C) Adjuvant
D) Toxin
E) Partial cell attenuated

Question 29

The change from negative serum, without antibodies specific to an infecting agent, to positive serum, containing antibodies against that infecting agent, is called

A) seroconversion.
B) complement fixation.
C) ELISA.
D) serum reversion.
E) serology.

Question 30

Precipitation reactions carried out in agarose are called

A) hemagglutination tests.
B) immunodiffusion tests.
C) complement fixation tests.
D) ELISA tests.
E) disc diffusion assays.

Question 31

Agglutination tests can be used to detect 

A) bacteria AND viruses.
B) hormones AND drugs.
C) fungi, bacteria, AND viruses.
D) viruses, bacteria, AND hormones.
E) viruses, bacteria, fungi, hormones AND drugs.

Question 32

An immune complex is defined as

A) antigen combined with antigen.
B) antigen combined with antibody.
C) antibody combined with antibody.
D) complement combined with LPS.
E) complement bound to neutrophils.

Question 33

Immunological tests may determine the presence of

A) only antibody.
B) only antigen.
C) antigen or antibody.
D) neither antibody nor antigen.
E) only IgG.

Question 34

The vaccine that is stable to heat, has little unwanted material and causes minimal side effects is called a(n)

A) inactive vaccine.
B) peptide vaccine.
C) active vaccine.
D) toxoid.
E) lipid vaccine.

Question 35

Immunodiffusion tests

A) allow detection of specific antigens.
B) are a simple method that produces visible results in the zone of optimal proportion.
C) allow quantitation of antigen concentrations.
D) None of the choices is correct.
E) All of the choices are correct.

Question 36

Injection of a single antigen usually results in production of

A) antibody to a single epitope.
B) an antibody that recognizes several epitopes.
C) additional antigen.
D) epitopes against that particular antigen.
E) a number of antibodies each recognizing a different epitope.

Question 37

The serology test that may show the antigen-antibody complex as yellow-green under the microscope while using an ultraviolet light is known as the

A) Western blot.
B) fluorescent antibody test.
C) ELISA test.
D) agglutination test.
E) the Ouchterlony test.

Question 38

Precipitation occurs when

A) antigen combines with antigen at optimal proportions.
B) antibody combines with antibody at optimal proportions.
C) antibody combines with complement at optimal proportions.
D) antibody combines with antigen at optimal proportions.
E) antigen combines with complement at optimal proportions.

Question 39

A poorly understood, yet promising type of vaccine that causes the host to produce microbial antigens for a short time involves the use of

A) subunits.
B) DNA.
C) alum.
D) toxoids.
E) glycoproteins.

Question 40

Serological tests are most often conducted in

A) test tubes.
B) flasks.
C) graduated cylinders.
D) Petri dishes.
E) microtiter plates.

Question 41

Blood for transfusion is frequently tested for HIV by using the

A) complement fixation test.
B) agglutination test.
C) ELISA method.
D) Ouchterlony test.
E) light microscope.

Question 42

Active immunity develops only after a natural infection and not after vaccination.

Question 43

Would antibodies produced by a patient in response to infection be monoclonal, or polyclonal?

A) Since the infection is from only a single agent/microbe, the antibodies would be monoclonal.
B) Since a single pathogen has multiple epitopes, the responding antibodies to a whole pathogen would be polyclonal.
C) Since the pathogen would most likely mutate slightly during the infection (producing different epitopes), the responding antibodies would be polyclonal.
D) Since the pathogen would acquire and modify self-antigens during the infectious process, the antibodies produced during the response would be polyclonal.
E) Since only one B cell is ever activated in response to a pathogen, the antibodies that are produced would be monoclonal.

Question 44

Recombinant vaccines and inactivated vaccines typically require several shots to be effective.

Question 45

Alum is an adjuvant.

Question 46

Since many childhood diseases such as mumps and measles are rare now within the United States, why is it still important for children to be immunized against them?  

A) If we lose herd immunity by removing mandatory vaccination, our population will become susceptible to these illnesses again in a short period of time.
B) There is always the likelihood that an individual from another country could import one of these illnesses into the United States, sparking an outbreak of new infections, if we aren't all properly vaccinated.
C) By keeping the population vaccinated, we keep incidence rates of these illnesses very low. This helps to protect people that cannot be vaccinated (very young children, pregnant women, immunocompromised individuals, the elderly).
D) Many of these diseases are HIGHLY contagious, and commonly through respiratory droplet (airborne) transmission. This makes an outbreak within a susceptible population very possible. Keeping the population resistant through mandatory vaccination prevents this possibility.
E) All of the options are correct.

Question 47

Inactivated vaccines typically require booster shots.

Question 48

Which of the following tests allows the separation of cells according to their sizes, densities, and surface markers tagged by specific fluorescent antibodies?

A) Western blotting
B) ELISA
C) Fluorescence-activated cell sorter
D) FA test on a microscope slide
E) DNA gel electrophoresis

Question 49

A monoclonal antibody is typically IgE and recognizes several epitopes.

Question 50

What would be a primary advantage of using an attenuated agent rather than just a subunit of that agent for a vaccine?

A) An attenuated agent strongly stimulates both the humoral AND cell-mediated adaptive immune response, giving the best comprehensive long-term protection available.
B) There is no advantage. It's much more dangerous to use an attenuated agent over a subunit vaccine due to the possibility of reversion of the microbe to a pathogenic state.
C) An attenuated agent strongly stimulates ONLY the antibody production (humoral response) of the adaptive immune system. This provides the best and strongest long-term protection.
D) An attenuated agent strongly stimulates ONLY the cytotoxic T cell (CTL, cell-mediated) side of the adaptive immune system. This provides the best and strongest long-term protection.
E) There is no advantage. If a subunit is used from that agent, all the T cells that are activated will make antibodies against that single antigen, causing a very strong response.

Question 51

DNA vaccines are dangerous due to the possibility of the DNA causing reversion in the inactivated pathogen.

Question 52

The risk of serious illness from measles is 500 times greater than from vaccination against the disease.

Question 53

Attenuated agents often give rise to a long-lasting immunity.

Question 54

Which of the following methods allows monitoring of the progressive destruction of CD4 T cells during an HIV infection by tagging the cells with specific antibodies to CD4 surface proteins and measuring their concentrations in serum?

A) Western blot
B) ELISA
C) Latex beads agglutination
D) Fluorescence-activated cell sorter
E) FA test on a microscope slide

Question 55

Anti-human-gamma-globulin antiserum is often used in

A) direct fluorescent antibody tests AND indirect ELISA.
B) indirect ELISA AND Western blot.
C) Western blot AND indirect fluorescent antibody tests.
D) indirect fluorescent antibody tests.
E) indirect ELISA, Western blot, AND indirect fluorescent antibody tests.

Question 56

What would be a primary advantage of passive immunity with diseases such as tetanus or botulism?

A) Time. You can quickly neutralize the toxin with a passive administration of antibodies to save the patient's life during the period it takes for their own active immune response to occur.
B) Cost. It's much cheaper to administer a dose of antibodies harvested from the serum of an actively immunized animal or human than it is to administer a vaccine.
C) Safety of delivery. It's far safer to administer a dose of antibodies harvested from the serum of an actively immunized animal or human than it is to administer a vaccine.
D) Handling of treatment. It's difficult to keep vaccines stored properly to keep their potency, especially in countries without adequate refrigeration facilities. It's much easier to keep antibodies stable, even in extremes of heat and humidity.
E) Recovery time. Even if the person actually develops the disease, the antibodies that are delivered in passive immunity will actively seek out and destroy the pathogen, facilitating a quicker recovery.

Question 57

The effectiveness of DNA vaccines stems from the effective production of antibodies against the naked DNA molecule.

Question 58

Why is a False positive more significant in HIV testing of patients than in screening donated blood for transfusions?

A) It isn't-both are equally dangerous/significant. False positives in people can lead to psychological trauma, but False positives in blood could lead to the useful blood being discarded.
B) A False positive in a person is easily re-testable. This makes it more significant, because we would simply quickly retest the person to verify their actual HIV status.
C) A False positive in blood is easily re-testable. This makes it less significant, because we would simply quickly retest the blood to verify its actual HIV status.
D) This statement is backwards. False positives in blood testing are more significant. If the False positive rate is high, we're more likely to discard useful blood that may lead to acute blood shortages for patients needing transfusions.
E) This question is misleading because like all immunological testing, the HIV test is infallible and there is absolutely no possibility of False positive results.

Question 59

An adjuvant has been developed from lipid A.

Question 60

Agglutination reactions utilize particles rather than molecules.

Question 61

You explain to the class that ELISA tests may be direct or indirect. Please select the False statement regarding these tests.

A) In direct ELISAs, specific antigens in the sample are "captured" by antibodies that have been attached to the inside surface of the well
B) ELISAs have advantages over other common immunoassays in that they are easy to do and often require minimal technical skills.
C) ELISA tests are 100% accurate; unlike other immunoassays, ELISAs never yield False positive results, so additional testing is not required.
D) ELISA tests are often done in microtiter plates, allowing multiple samples to be tested all at once.
E) Indirect ELISAs require a labeled secondary antibody to detect the unlabeled first (primary) antibody.

Question 62

The initial test used to diagnose HIV is the ELISA test. This test is

A) a colorimetric assay that is used to locate enzyme-labeled antibodies bound to antigens, often in a microtiter plate.
B) a piece of equipment that separates and determines the relative concentrations and certain characteristics of fluorescent-antibody-labeled cells.
C) the use of fluorescence microscopy to locate fluorescently labeled antibodies bound to antigens fixed to a microscope slide.
D) a "sandwich method" in which a known antigen is trapped between two radioactively labeled microscope slides for viewing.
E) None of the answer choices is correct.

Question 63

Which of the following is NOT True of artificially acquired passive immunity?

A) It involves injecting a person with antibodies produced by other people or animals.
B) It can be used to prevent disease immediately before or after likely exposure to a pathogen.
C) It can be used to cure certain diseases.
D) It can be used to limit the duration of certain diseases.
E) It can be used to block the action of microbial toxins.

Question 64

Which of the following is NOT True of naturally acquired immunity? 

A) It is the gain of adaptive immunity through normal events, such as exposure to an infectious agent.
B) It involves injecting a person with antibodies produced by other people or animals.
C) It occurs as a result of breast feeding; the secretory IgA in breast milk protects the digestive tract of the child.
D) It occurs during pregnancy when the mother's IgG antibodies cross the placenta and protect the fetus.
E) These all characterize naturally acquired immunity.

Question 65

You are very concerned about the  child with leukemia  who was in your office before you saw the measles patient. You know that the two children had been in the same waiting room for at least 20 minutes and that measles is a highly contagious disease. You also know that the patient with cancer has not received his MMRV vaccine because

A) attenuated vaccines that contain fully virulent pathogens, and thus poses a significant risk to immunocompromised people who cannot fight off any microbial infection.
B) attenuated vaccines contain live but weakened disease agents; these may occasionally mutate to become pathogenic again, so there is some risk in giving these vaccines to immunocompromised people. 
C) all vaccines are dangerous because of the adjuvants and additives in them, and should only be given to people who are at significant risk of life-threatening diseases such as rabies.
D) measles, mumps, rubella, and varicella are very mild childhood diseases that pose no risk; the leukemia child's immune system is already overwhelmed by fighting that cancer.
E) the child with leukemia is only two, which is way too young to receive too many vaccines; he should probably only get the MMR vaccine before he goes away to college.

Question 66

A patient is tested for antibodies to a particular infectious agent and is found to be positive. What would account for the positive result in this person? 

A) The person is currently infected with the agent AND the person was previously vaccinated against the agent.
B) The person was previously vaccinated against the agent.
C) The person was infected with the agent sometime in the past AND the person is currently infected with the agent.
D) The person is currently infected with the agent, the person was infected with the agent sometime in the past, OR the person was previously vaccinated against the agent.
E) The person was previously exposed to the infectious agent OR the person was previously vaccinated against the agent AND the person is currently infected with the agent.

Question 67

One of your peers asks you to explain the term immunoassay. You tell him that it

A) is an in vivo test in which known antibodies or antigens are used to detect or quantify given antibodies or antigens.
B) is an in vitro test in which known antibodies or antigens are used to detect or quantify given antibodies or antigens.
C) is the study of in vitro antibody-antigen reactions, particularly those that detect antibodies in serum.
D) is an in vitro test that uses unlabeled antibodies to detect a very common antigen in a sample.
E) is an in vitro test in which unknown antigens are used to detect unknown antibodies.

Question 68

The type of immunity conferred by giving a person a vaccine is

A) natural passive immunity.
B) artificial passive immunity.
C) natural active immunity.
D) artificial active immunity.
E) artificial active AND passive immunity.

Question 69

Many inactivated vaccines contain an adjuvant, a substance that enhances the immune response to antigens. An adjuvant that uses a derivative of lipid A has recently been developed. Would lipid A work well as an adjuvant?

A) Yes. Lipid A alerts the immune system to the presence of Gram-negative bacteria. It would similarly alert the immune system to the components of a vaccine if used as an adjuvant in the vaccine.
B) Yes. Lipid A alerts the immune system to the presence of Gram-positive bacteria. It would likely also alert the immune system to the components of a vaccine if used as an adjuvant in the vaccine.
C) Yes. Lipid A alerts the immune system to the presence of Gram-negative AND Gram-positive bacteria. It would similarly alert the immune system to the components of a vaccine if used as an adjuvant in the vaccine.
D) No. Lipid A is actually unlikely to be successful as an adjuvant because it always causes an intense inflammatory reaction in a host, resulting in extensive tissue damage.
E) No. Lipid A is actually unlikely to be successful as an adjuvant because even minimal amounts of this molecule causes endotoxic shock in a person, usually resulting in death.

Question 70

Select the False statement regarding artificially acquired passive immunity.

A) Immune globulin is used to prevent or treat specific diseases, for example using rabies immune globulin (RIG) to protect against rabies.
B) It involves the use of antiserum (a preparation of serum that contains protective antibodies) or antitoxin (antibody preparation that protects against a given toxin).
C) Hyperimmune globulin is used to protect unvaccinated people who have been recently exposed to certain diseases, including measles and hepatitis A.
D) It occurs naturally in response to infections, and artificially in response to vaccination, when antigens are deliberately introduced into the body.
E) These statements are all False.

Question 71

The Western blot is used to confirm the results of an ELISA test. Which of the following is the correct sequence of steps involved in this procedure?
1) To determine if a patient's serum has antibodies specific for any of the proteins in the sample (in this case HIV proteins), some of that serum is added to the blot, after which unbound antibodies are washed off.
2) The antigen proteins separate according to size. The separated proteins in the gel are then transferred ("blotted") to a nylon membrane to immobilize them in the same positions they were in the gel.
3) A type of gel electrophoresis (SDS-PAGE) is used to separate the proteins of an antigen, which involves loading the sample onto a polyacrylamide gel matrix, and running an electrical current through it.
4) Labeled anti-human IgG antibodies are added, which bind to any serum antibodies that have attached to the proteins. Unbound labeled antibodies are then washed off and attached label is detected. 

A) 1, 2, 3, 4
B) 3, 2, 4, 1
C) 3, 4, 2, 1
D) 3, 2, 1, 4
E) 2, 4, 3, 1

Question 72

Why does passive immunity not give lifetime protection, while active immunity may?

A) In active immunity, the body's own lymphocytes respond, producing a memory cell population that can respond to a subsequent exposure to the same antigen. Passive immunity only lasts as long as the injected antibodies remain in the body.
B) In passive immunity, the body's own lymphocytes respond, producing a memory cell population that can respond to a subsequent exposure to the same antigen. Active immunity only lasts as long as the injected antibodies remain in the body.
C) In active immunity, the body's own lymphocytes respond, producing an effector cell population that continually produces antibodies for the duration of the person's lifetime. Passive immunity only lasts as long as the injected antibodies remain in the body.
D) In active immunity, the body's own lymphocytes respond, producing an effector cell population that continually produces antibodies for the duration of the person's lifetime. Passive immunity results in the production of antibodies only when an antigen is present.
E) This question is misleading. Both passive immunity and active immunity provide lifetime protection.

Question 73

You tell the class that ELISAs and Western blots are performed in a clinic or laboratory. However, there are a variety of tests that can be performed at home. With the oral fluid antibody self-test, a person swabs their own mouth and uses a kit to test the sample. The kit looks similar to a pregnancy test. Saliva is collected on a swab which is then inserted into the "tube" containing a test strip on which certain HIV proteins are bound. The saliva moves up the test strip until it reaches two windows on the tube - one is labeled C and the other is labeled T.  When the saliva reacts with the bound virus proteins, a color change is seen. Results are interpreted as follows: 
No color in the C window-test is not working.
Color in the C window but none in the T window-negative result.
Color in the C window and color in the T window-positive result. 
Given this information, select the False statement.

A) The C window is a positive control-if color appears there, it confirms that the test is working properly.
B) The T window is the test window. If color appears both there and in the C window, it indicates that anti-HIV antibodies are present in the person's saliva.
C) This test is an ELISA test that is used to detect antibodies in a person's saliva.
D) If color appears in the T window but not in the C window, the kit is not working properly.
E) This test is an ELISA test that is used to detect the presence of viral capsid proteins in a person's saliva.

Question 74

You explain to the parent of the child with measles the importance of vaccinations. She responds by saying that measles, mumps, rubella, and varicella are very rare diseases in developed countries and she doesn't want her child to go through getting her shots. She worries about the safety of the MMRV vaccine. Which is the best response regarding this concern? 

A) These diseases are rare BECAUSE of successful vaccination BUT the pathogens still exist and with enough susceptible hosts, they can spread in a population.
B) These diseases are rare BECAUSE of successful vaccination AND the MMRV vaccine is safe and does NOT cause autism.
C) An immunocompromised person such as your patient with leukemia depends on others being vaccinated to remain healthy (herd immunity) AND the MMRV vaccine is safe and is NOT associated with autism.
D) These diseases are rare BECAUSE of successful vaccination BUT the pathogens still exist, and with enough susceptible hosts they can spread in a population AND the MMRV vaccine is safe and does NOT cause autism.
E) These diseases are rare BECAUSE of successful vaccination, but the pathogens still exist, and with enough susceptible hosts they can spread in a population. The MMRV vaccine is safe and is NOT associated with autism, and immunocompromised people who cannot receive an attenuated vaccine depend on herd immunity to remain healthy.

Question 75

Which of the following is NOT an example of an inactivated vaccine?

A) Toxoid vaccines
B) Subunit vaccines
C) Conjugate vaccines
D) Virus-like particles
E) Adjuvants

Question 76

The MMRV vaccine is an attenuated vaccine, which means that the vaccine

A) contains empty virus capsids produced by genetically engineered microorganisms such as yeasts.
B) contains viruses inactivated with formalin or another chemical that does not significantly change the surface epitopes.
C) is composed of a weakened form of the pathogen that is generally unable to cause disease.
D) contains toxins that are treated to destroy the toxic part of the molecules while retaining the antigenic epitopes.
E) is composed only of key protein antigens or antigenic fragments from the pathogen.

Question 77

Attenuated vaccines have several advantages. Which of the following is NOT an advantage of these vaccines?

A) One or two doses of an attenuated agent are often enough to induce relatively long-lasting immunity.
B) Attenuated vaccines are very stable in all temperatures, so are easily transported to remote areas and do not require special storage.
C) The vaccine strain may be spread from the person being immunized to other non-immune people, thereby immunizing the contacts of the vaccine recipient.
D) Attenuated vaccines can sometimes be delivered orally or nasally, preventing the need for using syringes.
E) Attenuated vaccines cause a very strong cell-mediated immune response.