Vaccines

Question 1

Live vaccines - types
advantages
disadvantages

Answer 1

attenuated : loses its virulence but can still grow and elicit an immune response (MMR)
antigenically cross -reactive : not a human pathogen but shares enough identify to produce protective response ( smallpox, tb)

Question 2

Live vaccines -
advantages
disadvantages

Answer 2

Ad: only need small dose of antigen 2. stim immune response at the natural portal of entry 3. induce wide spectrum responses 4. long lasting immunity 5. may not require boosting

disad: 1. reversion of virulence 2. viral interference 3. liability on storage 4. contraindications of live vaccines - immunosuppressed , pregnant

Question 3

Inactivated or killed vaccines - types

Answer 3

Whole : whole organism, inactivated in such a way that it keeps its structural proteins intact ( poliovirus)

subunit: not the whole organism but a specific subunit containing the necessary antigenic determinants to elicit a protective immune response

1. toxoid- inactivated toxins ( diphtheria, tetanus) does not prevent replication of the organism
2. polysaccharide - ( meningitis, pneumococcal pneumonia, infants dont respond ) - conjugate vaccines , hook polysaccharides onto protein carrier
3. recombinant antigens - genetically engineered protein elicits protective immune response to the organism

Question 4

Inactivated / killed - advantages and disadvantages

Answer 4

ad: stable during storage and no interference from other viruses

dis: large amount of antigen is required
requires adjuvants
limited range of immune response
boosters are usually required
must define component for subunit vaccine
recent evidence: subunit not always as effective as whole, killed ( influenza)

Question 5

experiment vaccines

Answer 5

DNA vaccines - inoculation consist of DNA encoding viral protein, host cell take up the dna and produce the protein. the immunogenicity of these vaccines can be modified by adding cytokine DNA or costimulatory molecules

live vectors- self replicating vaccines, introduce microbial genes into cytopathic virus or bacteria as a vector- the organism will replicate and produce the protein

Question 6

passive immunization

Answer 6

transfer of antibody containing immunoglobulin to individuals - protection is immediate but NO MEMORY is generated

use: high risk for infection without sufficient time for active immunization
- immunosuppressed hosts

**limited duration of immunity , no immunologic memory, if still as risk immunize as well