Large Molecules - Biotechnology and Your Health: Pharmaceutical Applications - page 38

injections are the toxins —proteins that make us sick if the diphtheria
bacteria grow in our bodies. In response to the series of small
injections of these proteins, our bodies develop antibodies , protec-
tive proteins produced by our immune system in response to an
infection by a microbe . Once a person has been vaccinated (or has
recovered from a particular disease), the antibodies remain in the
body, on the lookout for the same microbe to invade again. If it
reenters the body, the antibodies react and help remove it.
Stop and Consider
How do childhood vaccinations help prevent serious diseases?
Can you provide some examples?
In addition to preventing disease, antibodies can also be
injected to treat a disease. People who develop diphtheria infection
may receive antibiotics and serum , the fluid part of blood, contain-
ing antibodies from animals that have been repeatedly injected
with small amounts of the poisonous protein from diphtheria
bacteria. The antibodies in the animal serum bind to the toxin
protein in the patient, making it harmless. These animal sera
(plural of serum ) are prepared very carefully to make sure they are
safe. That was not always the case. In St. Louis in 1901, during a
diphtheria epidemic, the serum of a retired milk wagon horse
named Jim, which was infected with tetanus, was used to manu-
facture the diphtheria antitoxin. After receiving the contaminated
vaccine, 13 children died of tetanus. The scandal led to the passage
of the 1902 Biologics Control Act, which gave the federal govern-
ment control over the production of biologic products, including
serums, vaccines , and antitoxins . Antivenoms —serum preparations
from horses or sheep that have been repeatedly injected with small
amounts of venom proteins—are used around the world to treat
snake and scorpion bites.