Chapter 18 Micro Flashcards
What is variolation?
Exposure of individuals to smallpox scabs by inhalation or through open wounds
What is vaccination?
Inoculation of cowpox virus into skin (Edward Jenner)
Why/how does vaccination work?
- Exposure generates a primary immune response producing antibodies and memory B- and T-cells.
- Secondary immune response upon re-exposure is therefore rapid and strong.
- Vaccination is one of the great achievements of modern medicine.
Measles
- Measles is caused by measles virus (paramyxovirus, – strand, unsegmented, enveloped, no animal reservoirs)
- Highly contagious, airborne spread by coughs and sneezes. Complications include blindness, inflammation of brain, pneumonia and death
Measles vaccine
- Highly effective for long-term protection against measles infection
- Live attenuated virus given with mumps and rubella (MMR vaccine) as shot and a booster
Why is vaccination useful?
- For disease prevention in individuals and the public at large
- Useful against viruses for which there are few or no treatments
- Does not require that everyone be vaccinated for it to be effective; herd immunity limits epidemics
- Commonly administered to children and adult travelers
What are the different types vaccines?
-Attenuated whole-agent vaccines (live) MMR, Sabin polio (OPV) -Inactivated whole-agent vaccines (killed) Salk polio (IPV) -Toxoids (inactivated toxins) Tetanus -Subunit vaccines (antigenic proteins or fractions) Acellular pertussis Recombinant hepatitis B SARS-CoV-2 -Conjugated vaccines The antigen is linked to another immunogenic molecule Particularly useful for polysaccharides Effective in children <18 months
What are mRNA vaccines?
- Against SARS-CoV-2 contain an mRNAs for just the Spike protein embedded within a lipid “nanoparticle”.
- The lipid nanoparticle protects the mRNA from degradation until the mRNA gets inside the cell where it can be translated
What is the first type of polio vaccine?
Inactivated whole-agent vaccine (killed): -Salk: Inactivated Polio Vaccine (IPV) 1955 -virus inactivated with formalin -injection, produces IgG in blood -prevents virus spreading to CNS
What is the second type of polio vaccine?
Attenuated whole-agent vaccine (live) -Sabin: Oral Polio Vaccine (OPV) 1962 -mutant “attenuated” virus strains -droplet or sugar cube, gut immunity -provides contact immunity
What is the varicella vaccine?
- prevents chicken pox in children
- can prevent shingles (zoster) in elderly
- no vaccine-associated deaths in 40M doses (safe)
- vaccination not routine in some countries (e.g., UK)
- vaccination required in 41 states in US
What is the HPV vaccine?
-there are more than 150 serotypes of HPV
-90% of genital warts caused by HPV Types 6 and 11
-70% of cervical cancers caused by Types 16 and 18
-Types 16 and 18 cause half of vaginal, vulval, penile, anal and oropharyngeal cancers
-Cervarix vaccine is against Types 16 and 18.
-Gardasil is against Types 6, 11, 16, and 18.
recommended for 11-12 year-old girls and boys
and women to 26 years old
**cervical cancer is one of the few preventable cancers
What is the Haemophilus influenzae type B vaccine (Hib)?
- conjugate vaccine: polysaccharide + protein
- H. influenzae type B causes meningitis
- polysaccharide alone doesn’t work well in children under 18 mos. of age
- conjugate is effective in kids, who have immature immune systems
- herd immunity: giving vaccine to children reduces H. influenza type B infections in adults
- H.i.B polysaccharide fused to either tetanus, diptheria or meningococcal proteins
- Hib vaccine is one of WHO’s Essential Medicines
What is control, elimination, eradication?
-Control: Reduction to an acceptable level
-Eradication: Permanent reduction to zero of the worldwide incidence of infection caused by a specific agent as a result of deliberate efforts; intervention measures are no longer needed.
Example: smallpox
-Elimination of disease: Reduction to zero of a disease’s incidence in a defined area.
-Elimination of infections: Reduction to zero of infection in a defined area. Example: polio.
What is extinction?
The specific infectious agent no longer exists in nature or in the laboratory.
Example: none
How was smallpox eradicated?
- First effort was in 1950
- 1980 was declared eradicated
- Jenner first used cowpox in 1792
What are some characteristic to develop new vaccines?
- Must be profitable
- Must be able to culture pathogen
- Recombinant DNA techniques
- Adjuvants
- Deliver in combo
There are no useful vaccines for what?
chlamydias, fungi, protozoa, helminths
HIV*
those against cholera and tuberculosis are not reliable
the easy vaccines may have already been made
What vaccines are still in the experimental stage?
Ebola
-Using AAV or VSV viruses to deliver Ebola
Why are oral vaccines useful?
- easy to admin
- effective for protection at mucous membranes
What is the therapeutic index?
risk vs benefit
Example: OPV sometimes causes poliomyelitis
What is the Global Eradication Initiative?
- Program to eradicate polio primarily funded by Bill Gates
- Has reduced polio incidence of 99%
What is an example of diagnostic immunology?
Koch’s experiment:
-Guinea pigs with TB injected with Mycobacterium tuberculosis: Site became red and slightly swollen
-like the Tuberculin (or Mantoux) test
due to cell-mediated immunity
What is sensitivity?
True positive rate. Probability that the test is reactive if the specimen is a true positive
