Lecture 16 Flashcards
immunological memory and vaccination
How was protection against smallpox achieved?
Cowpox and smallpox share similar Ag so immunization with cowpox induced Ab against cowpox surface Ag. The Ab binds to and neutralizes the smallpox virus so it can’t bind anywhere.
What is passive immunization? (vague description)
It is where preformed Ab is transferred to a recipient. Examples include maternal IgG and IgA or the injection of Ab against tetanus or rabies.
What is active immunization? (vague description)
It is receiving a previous infection, so the body produces its own Ab. Examples include vaccinations.
What are some features of passive immunization?
no memory response, transient protection, short-term protection, delivers pre-formed Ab
Explain herd immunity.
Her immunity is a concept that shows the higher the rates of a vaccination in a given population, the more protected the population is against disease. Herd immunity requires a certain percentage of a population to be vaccinated for this concept to be effective. It prevents disease outbreak.
Give an example of a time in history when there was a distrust of vaccines.
In the late 90s Andrew Wakefield published an article claiming that the MMR vaccine caused autism. This caused vaccination rates in England to drop below the threshold required for herd immunity, and an outbreak of measles occurred. The paper was formally retracted and Wakefield was banned from practicing medicine since the correlation was actually due to the correlation of children receiving the vaccine at the same age that behavioral symptoms of autism began to arise.
What are some features of effective vaccines?
must not cause illness or death, and protect against illness upon exposure to live pathogens, lasts several years, induces neutralization and T cell activation
What types of vaccines exist? Describe each one.
- whole organisms: attenuated virus or inactivated version
- purified macromolecules: toxoids and capsula polysaccharides
- DNA vaccines
- RNA vaccines: SARS-Cov2
- recombinant vectors
What is attenuation?
It is achieved by growing a pathogen under abnormal culture conditions, an attenuated virus can replicate within host cells and induce a cell-mediated response, leading to long-lasting immunity
Explain the process of attentuation.
pathogenic virus is isolated and grown in human cultured cells, the cultured virus is then used to infect monkey cells, where the virus acquires a variety of mutations allowing it to grow well in the monkey, the virus can no longer grow well in human cells and can be used as a vaccine because while it still triggers an immune response, its presence will not cause an actual infection of the virus
How to inactivated “killed” vaccines work?
The pathogen is killed by heat before injection, which elicits an immune response, and the virus cannot replicate in the host. It induces a humoral response that is not long-term term so boosters of this type of vaccine are usually needed. This type of vaccine must be injected which is a disadvantage.
What are examples of subunit vaccines?
- Toxoids, which purify bacterial exotoxin
- Bacterial polysaccharide capsules, which induce anti-capsule Ab to increase PMN and Mac activity
- Recombinant protein Ag, which need more effective adjuvants
What are DNA vaccines? How do they work?
They are plasmids carrying pathogen genes injected into muscle tissue. The host takes up the DNA and expresses it internally so it provides Ag presentation via MHC class I stimulating CTL production.
What is an adjuvant?
It’s included in a vaccine to enhance the immune response
What are two ways adjuvants improve vaccines?
They promote inflammation by recruiting more immune cells and slow down Ag release for longer interactions
What shape are rabies virons?
bullet-shaped
How long does it take for the rabies virus to reach the brain after being bitten by an infected individual?
3 to 12 weeks
What treatment occurs on the day of exposure to the rabies virus?
intravenous human rabies immunoglobulin transfusion (passive) and rabies vaccine (active)
What was the key to developing the SARS-Cov2 vaccine?
replicating the spike proteins
What is the normal average time it takes to produce a vaccine?
15 years or longer
Why did current production of the SARS-Cov2 vaccine get produced so much faster?
the preclinical studies were much shorter due to previous studies done on the corona virus…the clinical trials were much shorter as well.
What does CPD stand for?
codon pair deoptimization
How does codon pair deoptimization work?
Large-scale recoding increases the frequency of under-represented codon pairs WITHOUT CHANGING CODON USAGE
How was the attenuated SARS-Cov2 created?
The RNA genome underwent codon pair deoptimization
