Microbiology and Immunology

Prusiner, Stanley WORLD OF MICROBIOLOGY AND IMMUNOLOGY

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malaria is still a major cause of death in the tropics. Although

certain drugs have been developed to protect people from

Plasmodium many forms of malaria have now developed,

some of which are even immune to the strongest medicines.

While malaria is one of the best known diseases known

to be caused by protozoans, a wide range of other equally dev-

astating ailments are also caused by protozoan infections.

Amoebic dysentery, for example, is caused by Entamoeba his-

tolytica.; African sleeping sickness, which is spread by the

bite of the tsetse fly, is caused by the flagellate protozoan

Trypanosoma; a related species T. cruzicauses Chagas’ dis-

ease in South and Central America; Eimeria causes coccidio-

sis in rabbits and poultry; and Babesia, spread by ticks, causes

red water fever in cattle.

Not all protozoans are parasites however, although this

is by far a more specialized life style than that adopted by free-

living forms. Several protozoans form a unique, nondestruc-

tive, relationship with other species, such as those found in the

intestine of wood-eating termites. Living in the termites’ intes-

tines the protozoans are provided with free board and lodgings

as they ingest the wood fibers for their own nutrition. In the

process of doing so, they also release proteins which can be

absorbed by the termite’s digestive system, which is otherwise

unable to break down the tough cellulose walls of the wood

fibers. Through this mutualistic relationship, the termites ben-

efit from a nutritional source that they could otherwise not

digest, while the protozoans receive a safe home and steady

supply of food.

See also Amoebic dysentery; Entamoeba histolytica;

Epidemiology, tracking diseases with technology; Waste water

treatment; Water quality

PPrusiner, Stanley RUSINER, STANLEY(1942- )

American physician

Stanley Prusiner performed seminal research in the field of

neurogenetics, identifying the prion, a unique infectious pro-

tein agent containing no DNAor RNA.

Prusiner was born on in Des Moines, Iowa. His father,

Lawrence, served in the United States Navy, moving the fam-

ily briefly to Boston where Lawrence Prusiner enrolled in

Naval officer training school before being sent to the South

Pacific. During his father’s absence, the young Stanley lived

with his mother in Cincinnati, Ohio. Shortly after the end of

World War II, the family returned to Des Moines where

Stanley attended primary school and where his brother, Paul,

was born. In 1952, the family returned to Ohio where

Lawrence Prusiner worked as a successful architect.

In Ohio, Prusiner attended the Walnut Hills High

School, before being accepted by the University of

Pennsylvania where he majored in Chemistry. At the

University, besides numerous science courses, he also had the

opportunity to broaden his studies in subjects such as philoso-

phy, the history of architecture, economics, and Russian his-

tory. During the summer of 1963, between his junior and

senior years, he began a research project on hypothermia with

Sidnez Wolfson in the Department of Surgery. He worked on

the project throughout his senior year and then decided to stay

on at the University to train for medical school. During his

second year of medicine, Prusiner decided to study the surface

fluorescence of brown adipose tissue (fatty tissue) in Syrian

golden hamsters as they arose from hibernation. This research

allowed him to spend much of his fourth study year at the

Wenner-Gren Institute in Stockholm working on the metabo-

lismof isolated brown adipocytes. At this he began to seri-

ously consider pursuing a career in biomedical research.

Early in 1968, Prusiner returned to the U.S. to complete

his medical studies. The previous spring, he had been given a

position at the National Institutes of Health (NIH) on com-

pleting an internship in medicine at the University of

California San Francisco (UCSF). During that year, he met his

wife, Sandy Turk, who was teaching mathematics to high

school students. At the NIH, he worked on the glutaminase

family of enzymesin Escherichia coliand as the end of his

time at the NIH began to near, he examined the possibility of

taking up a postdoctoral fellowships in neurobiology.

Eventually, however, he decided that a residency in neurology

was a better route to developing a rewarding career in research

as it offered him direct contact with patients and therefore an

opportunity to learn about both the normal and abnormal nerv-

ous system. In July 1972, Prusiner began a residency at UCSF

in the Department of Neurology. Two months later, he admit-

ted a female patient who was exhibiting progressive loss of

memory and difficulty performing some routine tasks. This

was his first encounter with a Creutzfeldt-Jakob disease (CJD)

patient and was the beginning of the work to which he has

dedicated most of his life.

In 1974, Prusiner accepted the offer of an assistant pro-

fessor position from Robert Fishman, the Chair of Neurology

at UCSF, and began to set up a laboratory to study scrapie, a

parallel disease of human CJD found in sheep. Early on in this

endeavor, he collaborated with William Hadlow and Carl

Eklund at the Rocky Mountain Laboratory in Hamilton,

Montana, from whom he learnt much about the techniques of

handling the scrapie agent. Although the agent was first

believed to be a virus, data from the very beginning suggested

that this was a novel infectious agent, which contained no

nucleic acid. It confirmed the conclusions of Tikvah Alper and

J. S. Griffith who had originally proposed the idea of an infec-

tious protein in the 1960s. The idea had been given little cre-

dence at that time. At the beginning of his research into prion

diseases, Prusiner’s work was fraught with technical difficul-

ties and he had to stand up to the skepticism of his colleagues.

Eventually he was informed by the Howard Hughes Medical

Institute (HHMI) that they would not renew their financial

support and by UCSF that he would not be promoted to tenure.

The tenure decision was eventually reversed, however,

enabling Prusiner to continue his work with financial support

from other sources. As the data for the protein nature of the

scrapie agent accumulated, Prusiner grew more confident that

his findings were not artifacts and decided to summarize his

work in a paper, published in 1982. There he introduced the

term “prion,” derived from “proteinaceous” and ‘infectious”

particle and challenged the scientific community to attempt to

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