Microbiology and Immunology

Vaccine WORLD OF MICROBIOLOGY AND IMMUNOLOGY

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sented again to the lymphocytes, as happens in the second vac-

cination in a series, the many lymphocytes are stimulated to

divide into daughter cells, which in turn form antibodies.

Thus, the second time around, a great deal more antibody is

produced. The antibody response also becomes highly specific

for the target. For example, if the target is a virus that causes

polio, then a subsequent entry of the virus into the body will

trigger a highly specific and prompt immune response, which

is designed to quell the invader.

Most vaccinations involve the injection of the immune

stimulant. However, oral vaccination has also proven effective

and beneficial. The most obvious example is the oral vaccine

to polio devised by Albert Sabin. Oral vaccination is often lim-

ited by the passage of the vaccine through the highly acidic

stomach. In the future it is hoped that the bundling of the vac-

cine in a protective casing will negate the damage caused by

passage trough the stomach. Experiments using bags made out

of lipid molecules (liposomes) have demonstrated both pro-

tection of the vaccine and the ability to tailor the liposome

release of the vaccine.

The nature of vaccination, with the use of living or dead

material that stimulates the immune system, holds the poten-

tial for side effects. For some vaccines, the side effects are

minor. For example, a person may develop a slight ache and

redness at the site of injection. In some very rare cases, how-

ever, more severe reactions can occur, such as convulsions and

high fever. However, while there will always be a risk of an

adverse reaction from any vaccination, the risk of developing

disease is usually far greater than the probability of experi-

encing severe side effects.

See alsoAdjuvant; Anti-adhesion methods; Immune stimula-

tion, as a vaccine

VVaccineACCINE

A vaccine is a medical preparation given to provide immunity

from a disease. Vaccines use a variety of different substances

ranging from dead microorganismsto genetically engineered

antigens to defend the body against potentially harmful

microorganisms. Effective vaccines change the immune sys-

temby promoting the development of antibodies that can

quickly and effectively attack a disease causing microorgan-

ism when it enters the body, preventing disease development.

The development of vaccines against diseases ranging

from polio and smallpoxto tetanusand measlesis considered

among one of the great accomplishments of medical science.

Vaccination via injection.

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