immunization pt 1

Question 1

immunization is…

Answer 1

the use of a specific immune response to prevent or lessen the severity of disease resulting from infection or the products of an infection ex. toxins

Question 2

objectives of immunization

Answer 2

• individual protection from infection (may be gen pop or specific risk groups)
• when a sufficient number of people are immune, infecting agents can not circulate in a pop (herd immunity- protects those who remain susceptible)
• elimination of infecting organism may persist

Question 3

action of antibodies

Answer 3

• may bind to an antigen and block its biological activity “neutralizing antibody”
  ex. viruses or toxins which are then called “neutralized”
• coat a bacterium and make it more easily phagocytosed by an immune cell
  “opsonization” improves clearance of organisms
• bind to an organism and activate complement system, cause lysis, and recruit immune cells to the area

Question 4

vaccines create an immunological memory: b cells…

Answer 4

• antibodies are produced by b lymphocytes that are activated to become plasma cells
• each one produces an antibody that is specific for its target
• when stimulated by an infection or vaccine the specific b cell clone multiplies
• some of these cells become b memory cells and are long lived to allow a rapid response to subsequent exposure

Question 5

immunological memory: t cells

Answer 5

• specific t lymphocytes also survive as memory t cells and remain to regulate the immune response
  
  • these are long lived cells in the lymphoid tissue, on re-exposure to the antigen they will multiply and shorten the time to a response
• t lymphocytes regulate the immune response and cytotoxic t cells kill infected cells

Question 6

passive immunization is when

Answer 6

the host receives antibody produced by another host
- this protection is short-lived (2-3 months) and no long term protection is generated
ex. IVIG, hep b, rsv, varicella zoster

Question 7

naturally occurring passive immunization

Answer 7

the neonate receives antibody transplacentally from the mother or in colostrum

Question 8

therapeutic passive immunity

Answer 8

antibody (immunoglobulin or Ig) is given:
- to provide rapid protections after exposure
- to lessen severity of ongoing disease
- for individuals unable to produce antibody

Question 9

generation of immunity

Answer 9

• done by administering an antigen to elicit an immune response in the host
• among the first types of jenner’s cowpox virus to prevent smallpox

Question 10

types of active immunization can be divided into”

Answer 10

• live attenuated (MMRV)
• virus vectors, replicating/non-replicating
• inactivated whole cell, subunit, virus like particles
• dna, rna (covid19 mrna vaccine)
• toxoid

Question 11

live attenuated vaccine

Answer 11

ex. BCG
- these use organisms which are limited in their ability to cause disease but share antigenicity w the virulent forms
- attenuated organisms are those that have been repeatedly cultured in the lab until they have lost their virulence properties
- administration need not be by injection, and may mimic the natural route of infection
- they have the advantage that they mimic the natural infection and give stronger and longer immunity (may not need booster dose)

Question 12

live attenuated disadvantages

Answer 12

• may be virulent for immunosuppressed ppl or in pregnancy
• they may revert to the virulent form during the infection in the host
• they must be handled properly to maintain viability until they are used (hard to transport/store)

Question 13

examples of live attenuated vaccines

Answer 13

• BCG vaccine for tuberculosis
• MMRV
• Sabin polio vaccine - once polio is eradicated from a pop the vaccine can become harmful as this one esp can revert to the virulent form

Question 14

replicating virus vectors

Answer 14

viruses that don’t cause human disease and are engineered to express (or cause the expression) of target virus protein
- this allows an immune response to the target virus without infection by it
- genes for the relevant protein are inserted into the virus vector
- mimics are real infection to give a strong immune response (ex. ebola)

Question 15

non-replicating virus vectors

Answer 15

• a carrier virus is treated so it can not replicate or cause disease
  ex. adenovirus
• a gene from the target virus added to the carrier virus so that it expresses the target virus protein
• gives a better immune response than a protein subunit vaccine

Question 16

types of inactivated vaccines

Answer 16

• these include whole cell, subunit, and virus like particles vaccine
• they are often given w a substance that increases their immunogenicity (an adjuvant)
• conjugation of polysaccharide to protein improves response
• boosters to remain effective

Question 17

examples of inactivated vaccines

Answer 17

ex. influenza vaccine, hep a vaccine
- given by injection - do not give a local IgA response (mucosal immunity)
- require multiple doses at specific intervals, reimmunization may be required
- they give an antibody response but not cell mediated immunity

Question 18

subunit vaccines

Answer 18

these are made w purified antigens derived from the pathogen and which are found to produce an effective immune response
- these are less prone to side effects than whole cell and are often very effective, but expensive

Question 19

subunit vaccine examples

Answer 19

• hep b vaccine where the outer coating antigen is used
• whooping cough vaccine
• influenzae type B, pneumococcal , and meningococcal vaccine

Question 20

virus like particles are …

Answer 20

the shell that can self assemble to resemble these pathogens
- prepared from viral proteins to form particles, no nucleic acids so not possible to cause disease
ex. HPV vaccine and hepatitis B vaccine

Question 21

RNA vaccines

Answer 21

made of messenger RNA that instructs our cells to produce a viral protein from the target virus
- the protein causes an immune response
- rna is unstable so needs to be in a lipid envelope and kept at very low temps - hard to transport and store

Question 22

dna vaccines

Answer 22

• similar to rna vaccines but more stable
• plasmid is injected which includes a gene for a target virus protein
• cells make the protein and elicit an immune response
• more easily stored/transported
• has to get into cell nucleus to work
• potential for incorporation into genome (w possible oncogenicity?)

Question 23

toxoids

Answer 23

these are inactivated toxins
- immunization protects from the action of the toxin
- multiple doses are given, w an adjuvant to increase immunogenicity
- these have been VERY effective vaccines
ex. tetanus and diphtheria toxoid vaccines