1.4 disease prevention thru vaccination medical interventions PLTW

how to make similar pathogen vaccine

• Collect a sample of the similar pathogen

• Purify the sample

• Insert purified pathogen into a syringe

how to make attenuated vaccine

• Obtain the pathogen

• Replicate/grow the pathogen in a tissue culture

• Weaken the pathogen through environmental conditions (ex. changing temperature/pH) that is unlike the human body conditions

• Choose the weakest strain of the pathogen

• Purify and isolate the weakest strain

• Insert weakest strain into a syringe

how to make killed vaccine

• Obtain the pathogen and grow in a tissue culture

• Purify and isolate the pathogen

• Kill the pathogen through heavy chemicals, heat, or radiation

• Insert killed pathogen into syringe

• Immune system recognizes antigens from the killed virus/pathogen → B cells generate antibodies

how to make toxoid vaccine

• Obtain a sample of pathogen and grow it in a tissue culture

• Isolate the toxin from the pathogen

• Neutralize the toxin with chemicals/calcium salt

• Add adjuvant which will boost the immune reaction to the toxin

• Insert neutralized toxin + adjuvant into syringe

• Researchers realized that treating tetanus with formaldehyde rendered it non toxic but kept its ability to trigger immunity

how to make subunit (conjugate) vaccine

• Pull out a subunit from the pathogen

  • subunit = DNA, RNA, or proteins

• Add the subunit to a host cell so that it can grow/replicate to make more copies of the subunit

• Use the purifier to isolate the antigen

• Insert the purified subunit into the syringe

• These vaccines focus immune responses on specific pathogenic components, such as proteins and polysaccharides 

• Hep B uses recombinant DNA technology to produce viral surface proteins 

how to make naked DNA vaccine

• Obtain target gene from the pathogen

• Make many copies of the gene through PCR

• Combine the gene with a vector (usually a plasmid)

• Stick the vector + gene combination in a host cell so the host cell can replicate

• Once the replication is done, purify the vector + gene

• Insert into syringe

• Delivers a plasmid (circular DNA) containing the genes to one of more of the pathogen’s antigens directly into human cells 

• Once inside the DNA is transcribed and translated and the antigen protein is produced

how to make mRNA vaccine

• Isolate the mRNA from the pathogen.

• Coat/enclose the mRNA in a lipid nanoparticle

• Stick the lipid nanoparticle into the syringe

• Instructs cells to produce viral proteins directly

  • mRNA is a type of genetic material that carries instructions for protein production

how to make viral vector vaccine

• Choose a virus that doesn’t make a human sick

• Select a subunit from this virus such as DNA, mRNA, or proteins. 

• Create the recombinant vaccine by combining the vector & subunit

• Grow the vector + subunit to produce the viral vector in large amounts

• Insert purified vector & subunit into syringe

• Employs harmless virus to shuttle 

example of similar pathogen vaccine

smallpox

example of killed (inactivated) vaccine

polio, typhus, rabies

example of toxoid vaccine

tetanus

example of subunit (conjugate vaccine)

hepatitis B, anthrax

example of mRNA vaccine

covid 19

example of viral vector vaccine

covid 19

restriction enzymes

• often described as the scissors of molecular biology ✂

  • Restriction enzymes cut DNA at specific, short DNA sequences. 

  • For DNA copying, restriction enzymes are able to cut the target gene and plasmid at specific sites, creating complementary “sticky ends” that allow the gene to be inserted into the plasmid. 

  • For vaccine production, the new recombinant DNA plasmid can be used to replicate the target gene by making many copies of the plasmid or by using the plasmid to produce the antigen. 

ligase

• often described as the glue of molecular biology

  • Ligase joins DNA fragments together

  • In DNA copying, ligase connects Okazaki fragments to ensure that the whole molecule is complete

  • In vaccine production, ligase is in charge of glueing the pieces back together. 

  • Restriction enzymes cut a piece of the DNA from the target antigen and the plasmid. The antigen DNA is inserted into the plasmid and is glued together by ligase. 

  • This creates a recombinant DNA molecule that can be used for vaccine production by growing the plasmid in large amounts and isolating the antigen. 

sticky ends

• Sticky ends are created when DNA is cut asymmetrically

• Sticky ends are important because its asymmetrical nature makes it easy to base pair with complementary DNA molecules in a plasmid to form the recombinant molecule. 

critera for choosing a restriction enzyme

• Do not use a restriction enzyme that digests the plasmid into many tiny pieces

• Use a restriction enzyme that produces sticky ends

• Do not use a restriction enzyme that leaves off more than 20 base pairs on either side of the viral DNA

• The enzyme shouldn’t interrupt antibiotic resistance genes in the plasmid or origin of replication. 

• Sticky ends need to be created on either side of the plasmid & viral DNA

what is a cohort study?

• A cohort study is also known as a prospective study

• The investigator selects a group of exposed individuals (individuals who have been exposed to the potential risk factor) and a group of non exposed individuals.

• The investigator follows both groups over time to determine the incidence of disease.

• A cohort study allows investigators to link a risk factor to the development of the disease.

what is a case-control study

• A case-control study is also known as a retrospective study

• A group of individuals with the disease identified (cases) are compared to a group of people without the disease (control).

• Cases and controls are matched on all criteria other than the one being studied. 

• A case-control study allows an investigator to make hypotheses based on past risk factors to see if a disease is caused. 

attack rate definition and formula

• Defined as the number of people at risk who develop a certain illness divided by the total number of people at risk

  • # of sick people / total # of people exposed

types of vaccines to prevent covid

1. mRNA vaccine

2. Vector Vaccine

3. Protein subunit vaccine

endemic

• Constant amount of a disease present in a specific location

elimination

• A disease is considered eliminated when it is no longer present in a specific geographic area

  • Example: eradication of polio in America or eradication of measles in Australia

eradication

• A disease is considered eradicated when it is no longer present worldwide

  • Example: eradication of smallpox in 1980

cluster

• Group of cases that occur in a limited area

Outbreak

• More cases than expected in a location in a given period

epidemic

• Outbreak with more cases or over a greater area or both

pandemic

• Bigger than an epidemic since it is often spread out over multiple countries/continents

Steps Involved in Vaccine Production & FDA Approval (3 phases)

• Isolate the virus particle

• Adapt the particle for a vaccine (weaken the virus, kill the virus, or use isolated pieces of the virus) or map the virus’s genetic sequence

• Genetically engineer particular virus genes and capture their blueprint 

  • Embed blueprint in DNA plasmid

  • Embed blueprint in RNA lipid

  • Embed blueprint in adenovirus

• Put particles into a solution then test

• Test in lab cultures and animals

  • If it’s too toxic or doesn’t stimulate the immune system or produce antibodies, stop testing

  • If it’s not too toxic and stimulates the immune system to produce antibodies, move to clinical testing

• Phase 1: Is the vaccine safe? Are bad side effects avoided? Does the immune system produce antibodies?

  • 10-100 people tested 

• Phase 2: Is the vaccine safe? Is the dosage correct?

  • 100s of people tested

• Phase 3: Does it prevent the infection across a large number of people?

  • 1000s of people tested

cytokine

• Small proteins secreted by the immune system that act as chemical signaling molecules to regulate and coordinate immune responses, inflammation, and other cellular processes. 
  

• Cytokines act as messengers in the immune system, allowing immune cells to communicate with each other to coordinate an attack

what are cytokine storms

• A response in the innate immune system that causes an uncontrolled and excessive release of cytokines. 

  • Sudden release of so many cytokines can lead to organ failure and death

  • Cytokine storms are often caused by viruses present in the body

  • Dangerous inflammatory response