Unit 1.4

Vaccinations

Unit 1.4 - OverviewLesson 1.4 Vaccination - Overview

Preface

In this unit, you have studied diagnostic tests used to identify disease agents and have examined how antibiotics can be used to treat bacterial infections.

In Lesson 1.4, you will discuss infectious disease prevention, specifically through vaccination.

In the aftermath of the bacterial meningitis cases at Sue’s school, all student medical records are reviewed and any student who did not receive the meningitis vaccine is called back in for immediate immunization. Vaccination is a valuable first line of defense against this debilitating infection and could make the difference between a few isolated cases and a full-blown outbreak.

Unit 1.4 - Overview

In the first activity of the lesson, you will study the history of vaccination through the eyes of scientist Edward Jenner. Smallpox, a highly infectious disease characterized by small lesions on the skin, ravaged society for centuries.

Edward Jenner• English physician/scientist who pioneered smallpox vaccine - the world's first

vaccine• In 1796 - Jenner inoculated James Phipps, an 8 year old boy • He scraped pus from cowpox blisters on the hands of a milkmaid who had

contracted cowpox and injected in both arms of Phipps• Phipps presented with a fever and some uneasiness, but no full-blown infection• Testing showed he developed an immunity to smallpox

Unit 1.4 - Overview

Vaccines trigger the production of antibodies against a particular pathogen; these antibodies circulate to protect the body when and if it encounters the true invader.

You will:

1) complete an Internet interactive and view a presentation to explore the techniques scientists use to produce vaccines

2) delve deeper into the science of molecular biology and learn how genetic engineering can be used to manufacture viable vaccines

3) scan simulated plasmid and viral DNA and choose an appropriate restriction enzyme to engineer a paper plasmid to produce a viral protein that can be used as a vaccine

4) explore the career field of epidemiology

Unit 1.4 - OverviewUnderstandings

Vaccines are medical interventions that activate the immune system to recognize a disease antigen and produce antibodies necessary to defend the body.

Vaccines can be produced in the laboratory by various methods, including recombinant DNA techniques.

Epidemiologists are dedicated medical professionals at the heart of the public health field who monitor the health of human populations, search for patterns in the development of both infectious and chronic illnesses, assist in outbreak investigations, and design disease treatment and prevention strategies.

Unit 1.4 - OverviewKnowledge and Skills

It is expected that you will understand:1) How vaccines interact with the human immune system.2) Many diseases have been eradicated by large-scale vaccination campaigns.3) Various laboratory methods that are used to manufacture vaccines.4) Plasmids can be employed as an important tool in genetic engineering and can

serve as vectors, vehicles for the movement of genetic information.5) How molecular tools such as ligase and restriction enzymes are used to cut and

paste DNA from different sources.6) How recombinant DNA technology can be used to produce vaccines.7) Appropriate steps in an outbreak investigation.8) The role of an epidemiologist to analyze disease data, design an epidemiologic

study, and evaluate prevention and therapy for chronic and infectious diseases.

Unit 1.4 - OverviewEssential Questions

1) What is vaccination?2) How does a vaccine activate the body’s immune system?3) How has vaccination impacted disease trends in our country?4) What methods are used to produce vaccines in the laboratory?5) What is recombinant DNA technology?6) What are the molecular tools used to assemble recombinant DNA?7) How can recombinant DNA and bacterial cells be used to produce vaccines?8) How can engineered plasmids be inserted into bacterial cells?9) What is epidemiology?10) How can epidemiologists assist with the detection, prevention, and treatment

of both chronic and infectious disease?

Unit 1.4 – Key Terms

Case-control studyCohort studyDNA ligase Epidemic Epidemiology Herd immunity Inoculation Plasmid Recombinant DNA Restriction enzyme Vaccination Vaccine

What is a vaccination and how does it work?

The body is presented a dead or weakened form of the pathogen to expose the immune system to the antigen.

This allows the B-cell to produce antibodies and memory cells.

Therefore, when the body is exposed to the antigen again the immune system will be able to fight off the infection.

How has vaccination impacted disease trends in our country?

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”.

Effective Vaccines

• Have low levels of side effects or toxicity.• Protect against exposure to natural, or wild forms of the

pathogen.• Should stimulate both an antibody (B-cell) response and

a cell mediated (T-cell) response.• Have long term, lasting effects that produce

immunological memory.• Should not require numerous doses or boosters• Are inexpensive, have a long shelf life and are easy to

administer.

Routes of Administration

• The majority of vaccines are administered by injection– Subcutaneous– Intramuscular– Intradermal

• Oral vaccines are available for only a few diseases

Methods Used to Produce Vaccines in the Laboratory?

• Killed• Attenuated• Toxoid• Subunit – recombinant DNA technology• Naked DNA• Similar Pathogen

2 goals for every vaccine– Contains Antigen so we can produce antibodies– Pathogen will not be harmful

Types of Vaccines

Killed whole cells or inactivated viruses– Pathogen is killed due to heat or radiation and inserted into

the body.– 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.

Types of Vaccines

Live, attenuated (weakened) cells or viruses– Pathogen is grown under non ideal conditions for several

generations, causing the pathogen to evolve. – Due to natural selection the pathogen is now adapted to the

new environment. – When placed in humans they still have the antigens, but will

be weak in the body’s environment so they will not harm.– Longer-lasting and require fewer boosters– Disease agent could mutate back to pathogenic strain

Types of VaccinesToxoid vaccines– Grow pathogen and collect the toxins produced by the

antigen . – Purified toxin injected into the person with another vaccine

and the body will elicit immune response.

Genetically engineered – Recombinant DNA Tech– Genes for microbial antigens are inserted into a plasmid

vector and are cloned in appropriate hosts.– The resultant protein product is used to provoke immune

system.

DNA vaccines – Naked DNA– These vaccines contain all or part of the pathogen DNA,

which is used to “infect” a recipient’s cells.

Subunit Vaccine

Gene for antigen from pathogen is put onto a plasmid and inserted into another organism. This organism can produce the antigen, which is used to produce the vaccine.

What is recombinant DNA technology?

joining together of DNA molecules (from two different species) that are inserted into a host organism to produce

new genetic combinations that are of value to science, medicine, agriculture, and industry.

What are the molecular tools used to assemble recombinant DNA?

• Restriction Enzymes cut DNA and open Plasmid• Ligase connect DNA fragment to plasmid at the sticky ends• This forms a recombinant plasmid that has a specific gene in it.

recombinant DNA

technology

Inserting engineered plasmids into bacterial

cells

• The recombinant plasmid is made and inserted into the bacteria via transformation.

• The bacteria can express the gene that was placed into the plasmid to produce the necessary antigen for the vaccine.

Similar Pathogen Vaccine

Insert a similar pathogen to what you want to vaccinate against. This pathogen is not as harmful to humans as the pathogen you are vaccinating against. It contains a similar enough antigen that we can develop antibodies to kill the pathogen.

Naked DNA Vaccine

Gene for antigen from pathogen is put onto a plasmid and inserted into a bacteria to replicate the plasmid. The plasmid is purified and placed into the body.

The body cells can uptake the DNA and begin making the antigen.

What is epidemiology?

Epidemiology is the study of the spread, cause, and effects of diseases in certain populations.

How can epidemiologists assist with the detection, prevention, and

treatment of both chronic and infectious disease?

• They analyze data, conduct surveys, and perform tests, to identify the cause and spread of the disease.

• They develop informative tools and use preventative measures to stop the spread of the disease.