Chapter 17 videos Flashcards
What are the two methods of Artificial immunity?
Active immunization
* Active artificially acquired
* Administration of antigens so that patient actively mounts an adaptive immune response
* Example: Vaccines
Passive immunization
* Passive artificially acquired
* Individual acquires immunity through the transfer of antibodies formed by immune individual or animal
What is a Vaccine?
suspension of organisms or fractions of organisms that is induced to cause immunity
What are requirments for effective vaccine?
- It should protect against exposure to natural, wild forms of pathogen.
- It should stimulate both antibody (B-cell) response and cell-mediated (T-cell) response.
- It should have long-term, lasting effects (produce memory).
- It should not require numerous doses or boosters.
- It should be inexpensive, have a relatively long shelf life, and be easy to administer.
What is active immunity?
Active Immunity
is the consequence of a person developing his own immune response to a microbe.
What are Attenuated (modified live) vaccines
- Use pathogens with reduced virulence
- Process of reducing virulence called attenuation
- Can result in mild infections
- Active microbes stimulate a strong immune response
- Can provide contact immunity
- Modified microbes may retain enough residual virulence to cause disease in susceptible individuals
What are Inactivated (killed) vaccines
- Safer than live vaccines
Whole agent vaccines
* Inactivated but whole microbes
Subunit vaccines
* Antigenic fragments of microbes
* Often require multiple doses to achieve full immunity
* Often contain adjuvants
* Chemicals added to increase effective antigenicity
What are Toxoid vaccines
- Chemically or thermally modified toxins used to stimulate active immunity
- Useful for some bacterial diseases
- Stimulate antibody-mediated immunity
- Require multiple doses because toxoids possess few antigenic determinants
What are combination vaccines?
- Research attempts to make vaccines more effective, cheaper, and safer
- Recombinant DNA techniques used to improve vaccines
What are Messenger RNA vaccines (mRNA vaccines)
- take advantage of the process that cells use to make proteins in order to trigger an immune response and build immunity
- Example: Covid-19 vaccine
Messenger RNA vaccines (mRNA vaccines) Mechanism of Action
- Scientists generated an mRNA sequence that codes for the virus spike protein
- The RNA sequence, a blueprint for making the spike, is swathed in a lipid coating for delivery
- Once it arrives, cells read the information in the mRNA sequence to produce millions of copies of the spike protein
- The protein fragments spur the immune system to produce antibodies that can protect when a real virus enters the body
What is Herd Immunity
- Herd immunity happens when a large part of the population – the herd - is immune to a pathogen.This can happen either because these people got vaccinated or had already been infected. Herd immunity makes it harder for a pathogen to spread
- Herd immunity protects the most vulnerable members of our population.
Herd Immunity importance the more contagious a pathogen?
- The more contagious a pathogen is, the more people need to be immune for herd immunity to kick in. The SARS-CoV-2 virus is so contagious that experts estimate about 70% of people in a community will need to be immune to have herd protection. Having vaccines should help eventually achieve that goal.
What are Problems associated with immunization
- Mild toxicity
- Risk of anaphylactic shock
- Residual virulence from attenuated viruses
- Allegations certain vaccines cause autism, diabetes, and asthma
- Research has not substantiated these allegations
What is passive immunity?
is the consequence of one person receiving preformed immunity made by another person.
What is Passive Immunotherapy?
- Administration of antiserum that
contains preformed antibodies - Provides immediate protection against a recent infection or ongoing disease
Antisera have several limitations - Can trigger allergic reactions called serum sickness
- Antibodies of antisera are degraded relatively quickly
- Individual not protected from subsequent infections
Passive immunotheropy vs active immunization graph
