Vaccines

Question 1

define characteristics of Ideal vaccine

Answer 1

• No undesirable side effects
• easy to administer
• highly immunogenic
• highly protective
• long-term immunity

No current vaccine meets all above criteria –> research continues to produce improved and new vaccines

Question 2

Define Attenuated viral vaccine

Answer 2

Prolonged passage of virus in other hosts –> decrease in human pathogenicity:

• Ex: sabin polio vaccine, measles, mumps, rubella, yellow fever
• Generates long-lasting immunity because virus can undergo limited replication –> greater antigenic stimulus to immune system (produce antibodies and cell-medaited component

Disadvantage:

• reversion of attenuated strain to full virulence
• contaminating pathogens
• often fatal problems for immunocompromised
• potential risk to the fetus

Question 3

Define Inactivated viral vaccine

Answer 3

Chemical treatment to inactivate virus:

• Advantages: less concern for safety compared to live vaccine, transport and storage are easier
• Disadvantage: don’t generate level of protection of live vaccines

Question 4

Define subunit viral vaccine

Answer 4

Consist of single viral protein

Question 5

Define inactivated bacterial vaccine

Answer 5

bacteria are heat killed to provide an antigen source

- not used anymore

Question 6

define Toxoid bacterial vaccine

Answer 6

bacterial toxins can be detoxified without loss of immunogenicity:

• e.g. diphtheria and tetanus toxoids used in DTaP vaccine
• -> in developing countries, immunization of pregnant women with tetanus vaccine aimed at protecting newborn with maternal antibodies. tetanus at umbilical stump is often fatal to the newborn

Question 7

define conjugate bacteria vaccines

Answer 7

Encapsulated bacteria have polysaccharide capsules:

• polysaccharides alone don’t produce high affinity antibody or immunologic memory
• conjugating polysaccharides to protein carrier –> high affinity IgG + memory response (trick immune system to think its an antigen)

Question 8

Define Hepatitis B vaccine

Answer 8

Adults = greater risk for being infected, but childhood immunization against hepatitis B is more convenient time

• Recombinant protein grown in yeast –> intramuscular injection
• -> serum antibody –> prevents virus from infecting liver

Infants born to HBsAg + mothers –> vaccine and hepatitis B immune globulin (HBIG)

Question 9

Define Diphtheria, tetanus, acellular pertussis vaccine (DTaP)

Answer 9

Formaldehyde-treated toxin –> D/T TOXOIDs (nontoxic, immunogenic)

Acellular vaccine = pertussis exotoxin

generates serum antibody to vaccine antigens –> will NOT eradicate bacteria, but will neutralize the toxins that cause disease. organisms will be eliminated by Host defense mech.

Question 10

Define Hemophilus influenzae type B vaccine

Answer 10

Capsular polysaccharide-protein conjugate vaccine:
–> T cell-dependent immune response

Proteins conjugated to capsular polysaccharides:
- tetanus toxoid, diphtheria toxoid, group B neisseria meningitidis outer membrane protein

Intramuscular injections provides protective serum antibody to stop bacteremic phase necessary to attack CNS

Question 11

Define Meningococcal vaccine

Answer 11

protects against 4 groups of Neisseria meningitidis (cause of miningitis)

Question 12

Defien Polio vaccine

Answer 12

Two vaccines:

1) inactivated (salk) poliovirus vaccine (IPV) - injected s.c.
2) Live, attenutated (sabin) oral poliovaccine (OPV)

• IPV generates seruma ntibodies to neutralize the virus in the bloodstream before reaches CNS.
• OPV develops local mucosal immunity in GI tract to prevent spread of cirus into bloodstream

Question 13

Define MUMPS, MEASLES, RUBELLA (MMR) vaccine

Answer 13

Live, attenuated –> protective serum antibodies + CMI

Rubella virus –> german measles –> rash, fever and join pain (only example of vaccination of one population is meant to protect another population

Question 14

Define Varicella vaccine

Answer 14

Live, Attenuated viral vaccine –> protection from chicken pox

• protective antibody response + cell mediated immunity
• Vaccine does NOT increase shingles

Question 15

Rotavirus vaccine

Answer 15

most common diarrheal pathogen in children worldwide

• -> tetravalent rhesus-human reassortant rotavirus vaccine (RRV-TV)
• attenuated rhesus virus expressing human virus VP7 antigen
• genome of rotavirus is segmented - coinfection with human and rhesus strains allows reassortants to emerge

Question 16

Define Pneumococcal vaccine

Answer 16

Vaccine is composed of S. pneumoniae polysaccharides conjugated to a carrier protein

Question 17

Define Influenza vaccine

Answer 17

Two types:

1) live attenuated vaccine is delived intranasally
2) inactivated vaccine

Vaccines contain one influenza A (H3N2) virus, one influenza A (H1N1) virus and one influenza B virus

Question 18

Define Human papillomavirus (HPV) vaccine

Answer 18

Vaccine = L1 protein-expressing virus-like particles:

• L1 is major capsid protein of HPV –> neutralizing antibodies protective
• targeted to females and males who have not become sexually active