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Vaccines

Whats that have to do with

Biomedical Engineering?

By: Jonathan Lloyd

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History of Vaccines

Smallpox was the first disease people tried toprevent by purposely inoculating themselves withother types of infections. smallpox inoculation

was started in India before 200 BC. In 1796 Britishphysician Edward Jenner tested the possibility ofusing the cowpox vaccine as an immunization forsmallpox in humans for the first time. The word

vaccination was first used by EdwardJenner. Louis Pasteur furthered the conceptthrough his pioneering work in microbiology.

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Vaccination

Vaccination (Latin: vacca

cow)is namedbecause the first vaccine was derived froma virus affecting cows, the relativelybenign cowpox virus, which provides a degree of

immunity to smallpox, a contagious and deadlydisease. Vaccination and immunization have thesame meaning but is different from inoculationwhich uses unweakened live pathogens. The

word "vaccination" was originally usedspecifically to describe the injection ofthe smallpox vaccine.

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Controversy?

Vaccination efforts have been met withsome controversy since their inception, onscientific, ethical, political, medical safety,religious, and other grounds. In rare cases,

vaccinations can injure people and in the UnitedStates they may receive compensation for thoseinjuries under the National Vaccine InjuryCompensation Program. Early success brought

widespread acceptance, and mass vaccinationcampaigns were undertaken which are creditedwith greatly reducing many diseases in numerousareas.

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Types of Vaccination

All vaccinations work by presenting a foreign

antigen to the immune system so there will

be an immune response, but there are

several ways to do this. The four main types

that are currently in clinical use are:

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Inactivated

An inactivated vaccine consists of virus particles whichare grown in culture and then killed using a methodsuch as heat or formaldehyde. The virus particles aredestroyed and cannot replicate, but the virus proteins

are intact enough to be recognized and rememberedby the immune system and evoke a response. Whenmanufactured correctly, the vaccine is not infectious,but improper inactivation can result in intact and

infectious particles. Since the properly producedvaccine does not reproduce, booster shots are requiredperiodically to reinforce the immune response.

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Attenuated

In an attenuated vaccine, live virus particles withvery low virulence are administered. They willreproduce, but very slowly. Since they do

reproduce and continue to present antigenbeyond the initial vaccination, boosters arerequired less often. There is a small risk ofreversion to virulence, this risk is smaller in

vaccines with deletions. Attenuated vaccines alsocannot be used by immunocompromisedindividuals.

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Subunit

A subunit vaccine presents an antigen to the immunesystem without introducing viral particles, whole orotherwise. One method of production involvesisolation of a specific protein from a virus or bacteria

and administering this by itself. A weakness of thistechnique is that isolated proteins may have a differentthree dimensional structure than the protein in itsnormal context, and will induce antibodies that maynot recognize the infectious organism. In addition,

subunit vaccines often elicit weaker antibodyresponses than the other classes of vaccines (McBean74).

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Virus-Like

Virus-like particle vaccines consist of viralproteins derived from the structural proteins of avirus. These proteins can self-assemble intoparticles that resemble the virus from which they

were derived but lack viral nucleic acid, meaningthat they are not infectious. Because of theirhighly repetitive, multivalent structure, virus-likeparticles are typically more immunogenic than

subunit vaccines. The humanpapillomavirus and Hepatitis C virus vaccines aretwo virus-like particle-based vaccines currently inclinical use.

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Genetic Engineering and Vaccines

Vaccination against a disease involves the

injection of killed or weakened

microorganisms into a person, as we know.

The killed or weakened microorganism is

made by engineers believe it or not. This

procedure has always carried the risk of there

being live, virulent pathogens in the vaccinebecause of some error in the vaccine-

producing process (LeVine 78).

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Vaccine Making(Subunit)

Genetic engineering techniques have been used to producevaccines which use only the parts of an organism whichstimulate a strong immune response. To create a subunitvaccine, researchers isolate the gene or genes which codefor appropriate subunits from the genome of the infectious

agent. This genetic material is placed into bacteria or yeasthost cells which then produce large quantities of subunitmolecules by transcribing and translating the insertedforeign DNA (Allen 23). These foreign molecules can beisolated, purified, and used as a vaccine. Hepatitis B vaccine

is an example of this type of vaccine. Subunit vaccines aresafe for immunocompromised patients because theycannot cause the disease.

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ANY QUESTIONS?

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Gildea, S. "A Comparison of Antibodies." Vaccines (2011). PubMed. Web.7 Oct. 2011.

McBean, Eleanor. The Poisoned Needle: Suppressed Facts aboutVaccination. Pomeroy, WA: Health Research, 1993. Print.

LeVine, Harry. Genetic Engineering: a Reference Handbook. Santa

Barbara, CA: ABC-CLIO, 2006. Print. "The History Of Vaccines And Immunization: Familiar Patterns, New

ChallengesHealth Aff."Health Affairs. Web. 08 Feb. 2011..

Allen, Arthur. Vaccine: the Controversial Story of Medicine's Greatest

Lifesaver. New York: W.W. Norton, 2007. Print. "GENETIC ENGINEERING." 56th World Science Fiction Convention -

Bucconeer 1998. Web. 08 Feb. 2011..