topic 18

Question 1

What is passive immunization? What are the risks?

Answer 1

preformed antibody

• Transiently protect a patient (e.g. immunosuppressed)
• Or alleviate an existing condition (e.g. toxin or venom exposure)
• Maternal antibody
• Risks: anaphylaxis, immune complexes

Question 2

What is active immunization?

Answer 2

• Administering an infectious organism or parts thereof in a manner that stimulates long-term protective immunity
• Active immunity is generated
• It has memory and specificity
• Natural infection also stimulates active immunity

Question 3

What are some goals of vaccination? What don’t vaccinations prevent?

Answer 3

• Reduce disease burden
• Reduce chance of transmission
• This limits the amount of circulating microorganism
• Leads to “herd immunity”

They prevent disease and death but not necessarily infection.

Question 4

What is needed for an effective immune response against 1)EC bacteria or fungi, 2)IC bacteria or viruses, 3) toxins

Answer 4

• Extracellular bacteria or fungi – Antibody for C’ fixation, opsonization
• Intracellular bacteria or viruses – T cells for macrophage activation, cytolysis – Antibody for neutralization (viruses)
• Toxins – Antibody for neutralization

Question 5

What are 5 types of vaccines?

Answer 5

Live attenuated, Inactivated, Toxoid, Subunit, Conjugate

Question 6

How are live attenuated vaccines created? What kind of immune response does it create? What diseases is it used for? What are the risks?

Answer 6

A pathogenic virus is taken from a human and cultured in human cultured cells. The cultured virus is put into a monkey. In the monkey, the virus acquires mutations that allow it to grow into the monkey but in so doing, it can no longer grow well in humans and can be used in a vaccine.

Similar to natural infection so stimulates Ab and cellular responses (T cells)

e.g. Measles, mumps, rubella, yellow fever, varicella, Mtb

Risks: disease in young or immunocompromised pts; reversion to virulence

Question 7

What do inactivated vaccines consist of? What is their safety? What immune response do they create?

Answer 7

Killed

• whole organisms rendered non-infectious
• stable, safer than live vaccines
• Ab+Th > CTL so not optimal for many viruses

Question 8

What does a toxoid vaccine consist of? What immune response does it create?

Answer 8

• inactivated bacterial toxin

- neutralizing antibodies

Question 9

What do subunit vaccines consist of? What is their safety? How do they work? What immune response do they create? What diseases do they work for?

Answer 9

• isolated protein components
• very safe
• must be mixed with adjuvant for effectiveness

these modify or alter a vaccine by mimicking PAMPs

• Th (and Ab) > CTL

Good for Hepatitis B, pertussis, s. pneumonia

Question 10

What do conjugate vaccines consist of? What population are they particularly used for? How do they work?

Answer 10

• Two different parts of microorganisms

(polysaccharide for Ab, protein for Th)

B cell recognizes polysaccharide, internalizes the complex, then present the protein to Th cells. Th cells then activate B cells to proliferate, and they form memory cells against the polysaccharide. Without the protein, in some cases, the b cell response alone (without Th cell help) won’t be enough to develop a good immunity.

• Particularly useful for young children

Question 11

What are two new types of vaccines in development?

Answer 11

DNA Vaccination and Recombinant Vector

Question 12

How does DNA Vaccination work? What are some advantages to it? What type of immune response does it elicit?

Answer 12

• inexpensive and stable
• plasmid mixtures. When plasma is placed into APC, it enters genome and is transcribed and translated into proteins. The proteins are processed and then presented in MHC 1 to T cells.
• CTL > Ab

Question 13

How are recombinant vector vaccines formed? What immune response do they elicit?

Answer 13

A recombinant plasmid with the gene of choice and a vaccinia promoter is mixed and cultured with the vaccinia virus. Through homologous recombination, the gene is placed into vaccinia virus genome and thus is expressed by vaccinia meaning immunity is created when that vaccinia virus is used as a vaccine.

• mimics natural infection
• strong cellular and humoral immune response

Question 14

What factors determine when people should receive vaccines?

Answer 14

Factors: Maternal Ab levels, safety, relative risk of exposure

Question 15

What antiviral vaccines are given in infancy?

Answer 15

HBV, rotavirus, poliovirus

Question 16

How do kids get HBV? What vaccines exist and what kind are they?

Answer 16

• kids acquire infection from blood or body fluids
• Recombivax HB and Engerix-B (HBsAg subunit)
• first anti-cancer vaccine

Question 17

Why is it important to administer the rotavirus vaccine? What are its goals? Compare and contrast rotateq and rotarix.

Answer 17

• nearly 100% infection rate by age 5
• major cause of hospitalizations
• often deadly in developing regions world-wide
• vaccine goals: reduce symptoms, then transmission

Rotateq:Genetic backbone Bovine/human rotavirus, Dosage schedule 3 doses at 2, 4, and 6 mo., oral

Rotarix: Human rotavirus, 2 doses at 2 and 4 mo, oral

Question 18

What bacteria are combated by DTaP? What does it consist of? What are the different kinds of vaccines given through the lifetime? What age group accounts for the most cases of pertussis? the most morbidity?

Answer 18

• Diphtheria+tetanus toxoids, acellular pertussis
(inactivated toxins, additional protein component)

DTaP - full series for children 40) account for most cases

Question 19

What diseases does the haemophilus influenzae B (Hib) vaccine protect against? At what age is its peak attack? What does it consist of?

Answer 19

• meningitis and deafness caused by H. influenza
  ; peak attack at 6-12 mo.
• conjugate vaccine with toxoid or other bact. protein

Question 20

What diseases does pneumococcus cause? What does the pneumococcal vaccine consist of?

Answer 20

• meningitis and pneumonia
• PCV13 (Prevnar 13) conjugate vaccine: purified
  capsular polysaccharide from 13 serotypes of S. pneumoniae conjugated to a diphtheria toxin variant

Question 21

What types of the influenza vaccine exist? What do they consist of?

Answer 21

• inactivated virus vaccine contains two A strains and one B strain (trivalent) – Fluzone for > 6 mo. of age
• live-attenuated, nasally administered form - FluMist/LAIV licensed for healthy people 2-49 years of age - recommended yearly for everyone
• new Flucelvax generated without eggs

Question 22

What antibacterial vaccines are safe to be given within the first year of life?

Answer 22

DTaP, haemophilus influenzae B (HiB), pneumococcus.

Question 23

What are two live attenuated viruses that are given starting at age 1? How effective are they?

Answer 23

• Measles, Mumps and Rubella (MMR)

• live attenuated viruses
• virtually eliminated measles in U.S. - incidence on the rise again ( classic example of herd immunity )

• Varicella (Varivax)
- 85% effective (breakthrough cases mild)

Question 24

Why is Hep A vaccine given to children ? What puts kids at risk for infection? Who is it given to?

Answer 24

• To reduce the transmission of hepatitis A to adults

children <5 yrs have the highest infection rate;
asymptomatic, and so are silent reservoirs

vaccination of kids led to 70-90% decrease in
Hep A infection of adults

• For kids at risk of infection due to:
• household contact
• living or traveling to areas where incidence is high

Not necessarily given to every child.

Question 25

What are two vaccines not given until adolescence or older if risk factors are present?

Answer 25

HPV, and Meningococcus

Question 26

What diseases does HPV cause in men, women, and both? Who is the Human Papilloma Virus Vaccine recommended for?

Answer 26

• Certain HPV types can cause cancers:

Women - cervical, vaginal, and vulvar cancer

Men - penile cancer

Both - anal and some oropharyngeal cancers

• Recommended for adolescent girls and boys

Question 27

What does the meningococcus vaccine consist of? What ages is it for? What is the yearly incidence of severe meningitis? What age group has the highest rates of disease? What 5 serogroups are responsible for most of the disease?

Answer 27

• 3000 cases of severe meningitis yearly

- infants

Question 28

Which vaccines are given to adults regularly? Which are given based on risk? What determines the timing of vaccines in older adults?

Answer 28

Influenza – yearly

Tdap/Td boost – every 10 yrs

Zostavax (zoster) – after age 50* to boost natural immunity to prevent Shingles

Meningococcal – dense housing situations (nursing home)

Hepatitis A-If traveling to another country.

Question 29

What pneumoccal vaccine is given to those 65 and older? What does it consist of? When would it be given to someone younger?

Answer 29

• Pneumococcal vaccine PPVSV (Pneumovax)
• polysaccharide from 23 of the 41 serotypes
• prevents death from S. pneumoniae
• also for younger adults at risk:
• chronic lung and heart disease
• asthma or a history of smoking or alcoholism
• diabetics
• lymphoma or leukemia; other immunocompromise
• Native American or Alaskan descent

Question 30

Why are HIV, Tuberculosis, and malaria so problematic? Why aren’t there effective vaccines for them? What is the goal for them?

Answer 30

• HIV, tuberculosis, malaria

• No or relatively ineffective vaccines
• Kill >4.3 million people annually, including
  kids and young adults
• Sophisticated immune evasion strategies
• Persistence

The goal is no longer “sterilizing immunity”, but rather lessening the transmission and extending life expectancy

Question 31

What are some considerations when trying to develop new vaccines?

Answer 31

• Conceptual Issues

• best type(s) of immune responses-“correlates of protection”
• pathogen immune evasion mechanisms

• Practicalities

• cost
• stability
• ease to administer
• multivalency

New vaccine development faces challenges of
organisms with complex lifecycles and immune evasion strategies