hh 1.4

VOCABULARY

Vaccine: A harmless variant of a pathogen that stimulates a host's immune system to mount defenses against the pathogen.

Vaccination: A procedure that presents the immune system with a harmless variant of a pathogen, thereby stimulating the immune system to mount a long-term defense against the pathogen.

• derived from Variolae vaccinae 

• Smallpox, a highly infectious disease characterized by small lesions on the skin, ravaged society for centuries. By exposing a healthy patient to cowpox, a similar, yet less lethal virus, Jenner was able to make this individual immune to smallpox

  • This method of transferring resistance, called vaccination, differed from previous attempts by medical professionals to produce artificial immunity. 

Inoculation: The introduction of a pathogen or antigen into a living organism to stimulate the production of antibodies.

Toxoids: Immunizations created using inactivated toxins

Recombinant DNA: A DNA molecule made in vitro with segments from different sources. (combining dna from different sources)

Plasmid: A small ring of DNA that carries accessory genes separate from those of the bacterial chromosome.

Restriction enzymes: A degradative enzyme that recognizes specific nucleotide sequences and cuts up DNA.

1.4.1

DIFFERENT TYPES OF VACCINES*

Live, Attenuated Vaccines

• Example: MMR (measles, mumps, and rubella)

• This vaccine uses a weakened form of the disease causing agent, and allows the immune system to create a defense against replicating pathogen

• Mutations may occur (e.g. OPV)

Killed or Inactivated Vaccines

• Ex. Hepatitis A

• Instead of using a weakened form of the pathogen, it uses a killed version of it. However, it does provide an immunity that is as strong as Live-attenuated vaccine

Toxoid Vaccines

• Ex. Tetanus

• Toxin produced by the bacterium

• Toxoid vaccine is used by inactivating the toxin that causes the disease symptoms

Subunit and Conjugate Vaccines

• Ex. Hepatitis B

• Subunit and conjugate use specific pieces of the pathogen they protect against. This can be done by isolating a specific protein from a pathogen and presenting it as an antigen on its own.

mRNA Vaccines

• Ex. Pfizer-BioNTech vaccine

• The mRNA vaccine directs cells to produce a protein, or a part of a protein, that’s associated with a pathogen

Viral Vector

• Ex. rVSV-ZEBOV

• Use a harmless virus to deliver genetic informations into your cell

Research additional information about the bacterial meningitis vaccine. List three to five reasons why teens should be vaccinated against this disease before going off to college

• There are two kinds of bacterial meningitis vaccines given to kids: the meningococcal conjugate vaccine (MenACWY) which protects against the four types of meningococcal bacteria (A, C, W & Y) and is recommended for all kids and teens age 11 years and older. 

• The second one is called meningococcal B Vaccine (MenB) which serves as a defense for the fifth type of meningococcal bacteria, type B. Additionally, the third one is known as MenABCWY that protects the body from the meningococcal bacteria A, C, W, and Y. vaccine CDC recommends vaccination for all preteens and teens including adults that are marked with a high risk of getting it.

• Teens and young adults are more likely to carry the bacteria that causes meningitis in their throats. In crowded living spaces like college dorms, germs can spread quickly

Explain why the MMR and DTaP vaccines are administered multiple times over the course of a child’s life. What does the term “booster shot” mean?

MMR and DTaP vaccines are administered multiple times over the course of the child’s life because it will make a child’s immune system stronger as a child. Children are prone to diseases, so vaccines that are being administered multiple times allows the immune response to last longer and develop into a better immune system. Lastly, booster shot means an additional shot after the first one

More than 250 years ago, when Edward Jenner tested his smallpox vaccine, he did so on a nine-year-old child. Fast forward to today, and the rules and regulations on vaccine testing are many. Researchers must balance the need to understand the vaccine’s efficacy while considering the safety of the patients in the trial. What ethical considerations do you think must be addressed when a new vaccine is being tested and released to the public?

• When a new vaccine is being tested and released to the public, ethical considerations such as honesty, significance of autonomy, and accountability. A scientist/healthcare worker must know and provide the information regarding the vaccines (ex. Side effects), must respect the patient’s decision or their guardian(s), and must take responsibility for the vaccines’ outcomes.

Most mentioned Vaccines

1.4.2

RECOMBINANT DNA TECHNOLOGY*

• The process of cutting and recombining DNA fragments.

1. Isolation of genetic material:

Extract the desired DNA sequence from the source organism, purifying it from other cellular components. 

2. Restriction enzyme digestion:

Use restriction enzymes to cut the DNA at specific recognition sites, creating "sticky ends" on the DNA fragments. 

3. Vector preparation:

Prepare a cloning vector (like a plasmid) by cutting it with the same restriction enzyme, creating complementary sticky ends to join with the desired DNA fragment. 

4. Ligation:

Mix the DNA fragments with the cut vector and add DNA ligase enzyme to join the DNA pieces together, forming recombinant DNA. 

5. Transformation:

Introduce the recombinant DNA molecule into a competent host cell (usually bacteria) allowing it to take up the new DNA. 

6. Selection and screening:

Select transformed cells containing the desired recombinant DNA using antibiotic resistance markers or other screening methods. 

7. Expression:

Once the desired gene is inside the host cell, induce (trigger) its expression to produce the desired protein

MAKING VACCINES

Effectiveness of Vaccines

• Low levels of side effects or toxicity

• A defense against exposure to the natural or wild forms of pathogens

• Usually stimulate B and T cells

• Prolonged effects which produce immunological memory

• Does not need booster shots multiple times

• Inexpensive, can be stored long enough, and can be given without any issues

Route of Administration

• Subcutaneous (SC):

  • Injection site: Fatty tissue layer beneath the skin. 

  • Absorption rate: Slower than intramuscular. 

  • Examples of medications: Insulin, certain vaccines. 

• Intramuscular (IM):

  • Injection site: Muscle tissue. 

  • Absorption rate: Faster than subcutaneous. 

  • Examples of medications: Many vaccines, certain antibiotics. 

• Intradermal (ID):

  • Injection site: Dermis layer of the skin. 

  • Absorption rate: Slowest of the three routes. 

  • Examples of medications: TB skin tests

• Oral Vaccines (only for a few diseases)

Types of Vaccines

• Killed whole cells or inactivated viruses 

  • Even though they are harmless, they still contain recognizable antigens on their surface. 

  • Because the microbe does not multiply, larger doses and more boosters are required.

• Live, attenuated (weakened) cells or viruses

  • Vaccines are longer-lasting and require fewer boosters.

  • However, the disease agent could mutate back to pathogenic strain.

• Toxoid Vaccines

  • A purified toxin produced by the antigen is used to elicit immune response.

• Genetically engineered microbes or microbial antigens

  • Genes for microbial antigens are inserted into a plasmid vector (like the vehicle) and are cloned in appropriate hosts

  • The resultant protein product is used to provoke immune system

• DNA vaccines

  • These vaccines contain all or part of the pathogen DNA, which is used to “infect” a recipient’s cells.

Herd Immunity

• More individuals that are immune decreases the incidence of the disease and the occurrence of the pathogen.

• With greater numbers immunized, it is less likely that an unimmunized person will encounter the pathogen.

• Mass vaccination confers indirect protection for those who do not receive the vaccine resulting in “herd immunity

1.4.3

Epidemiologists: dedicated medical professionals at the heart of the public health field, monitor the health of populations and search for patterns in disease.

Epidemiology: A branch of medical science that deals with the incidence, distribution, and control of disease in a population. They need to have the knowledge of:

• clinical medicine

• pathology

• biostatistics (the application of statistical methods to data relating to human biology, health, and medicine)

• social science (the study of human behavior and society

Epidemic: Affecting an atypically large number of individuals within a population, community, or region at the same time.

Epidemic Curve: graphical distribution of the times of onset of disease.

COHORT STUDY VS CASE-CONTROL STUDY

• Cohort 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 and follows both groups over time to determine the incidence of disease.

• Case-control study: a group of individuals with the disease are Identified (called cases) and compared to a group of people without the disease (called controls). Cases and controls are carefully matched on all criteria other than the one being studied. For example, cases and controls should be matched for age, sex, or for underlying medical conditions. These Individuals can then be surveyed about their exposure to the given risk factor.

Cholera

Tuberculosis 

Hantavirus pulmonary syndrome (HPS) 

Mad cow disease 

Avian influenza (bird flu) 

Malaria Lyme disease 

Cervical cancer 

Legionnaire disease 

Plague 

Measles 

Ebola hemorrhagic fever 

AIDS 

Smallpox 

Polio 

Anthrax 

West Nile Virus 

SARS 

COVID-19