Microbiology and Immunology

Baltimore, David WORLD OF MICROBIOLOGY AND IMMUNOLOGY

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In the last several decades, scientists have used phages

for research. One use of bacteriophages is in genetic engineer-

ing, manipulating genetic molecules for practical uses. During

genetic engineering, scientists combine genes from different

sources and transfer the recombinant DNA into cells where it

is expressed and replicated. Researchers often use E. colias a

host because they can grow it easily and the bacteria is well

studied. One way to transfer the recombinant DNA to cells uti-

lizes phages. Employing restriction enzymesto break into the

phage’s DNA, scientists splice foreign DNA into the viral

DNA. The recombinant phage then infects the bacterial host.

Scientists use this technique to create new medical products

such as vaccines. In addition, bacteriophages provide infor-

mation about genetic defects, human development, and dis-

ease. One geneticist has developed a technique using

bacteriophages to manipulate genes in mice, while others are

using phages to infect and kill disease-causing bacteria in

mice. In addition, microbiologists found a filamentous bacte-

riophage that transmits the genethat encodes the toxin for

cholera, a severe intestinal disease that kills tens of thousands

worldwide each year.

See alsoBacteria and bacterial infection; Biotechnology; Cell

cycle (prokaryotic), genetic regulation of; Chromosomes,

prokaryotic; Genetic regulation of prokaryotic cells;

Laboratory techniques in microbiology; Phage genetics;

Phage therapy; Viral genetics; Viral vectors in gene therapy;

Virus replication; Viruses and responses to viral infection

BBaltimore, David ALTIMORE, DAVID(1938- )

American microbiologist

At the age of 37, David Baltimore was awarded the 1975

Nobel Prize in physiology or medicine for his groundbreaking

work on retrovirus replication. Baltimore pioneered work on

the molecular biologyof animal viruses, especially poliovirus,

and his investigations of how viruses interact with cells led, in

1970, to the discovery of a novel enzyme, reverse transcrip-

tase. This enzyme transcribes RNAto DNAand permits a

unique family of viruses, the retroviruses, to code for viral

proteins. Baltimore shared the Nobel Prize with virologist

Renato Dulbecco and oncologist Howard Temin, who inde-

pendently discovered the same enzyme. Baltimore’s achieve-

ment had profound implications for the scientific community

because it challenged the central dogma of molecular biology,

which stated that the flow of genetic information was unidi-

rectional, running from DNA to RNA to proteins. His work

also contributed to the understanding of certain diseases such

as AIDS, now known to be caused by the retrovirus HIV.

David Baltimore was born in New York City to Richard

Baltimore and Gertrude Lipschitz. Baltimore was a gifted sci-

ence student while still in high school; he attended a presti-

gious summer program at the Jackson Laboratory in Bar

Harbor, Maine, in which he studied mammalian genetics. It

was during this program that he met his future colleague,

Howard Temin, and decided to pursue a career in scientific

research. As an undergraduate Baltimore attended Swarthmore

College in Pennsylvania and graduated in 1960 with high hon-

ors in chemistry. He started graduate work at the

Massachusetts Institute of Technology (MIT), but he trans-

ferred after one year to the Rockefeller Institute, now the

Rockefeller University, in New York. There he studied with

Richard M. Franklin, a molecular biophysicist specializing in

RNA viruses. Baltimore earned his Ph.D. in 1964 and then

completed three years postdoctoral research at the Salk

Institute in La Jolla, California. There he met Renato

Dulbecco, who developed innovative techniques for examin-

ing animal viruses, and Alice Shih Huang, who later became

his wife. Huang was Baltimore’s postdoctoral student at Salk,

collaborated in some of his viral research, and later became a

full professor at the Harvard Medical School. In 1968

Baltimore joined the MIT faculty, became full professor in

1972, and in 1973 was awarded a lifetime research professor-

ship by the American Cancer Society. After winning the Nobel

Prize in 1975 Baltimore continued to be honored for his work.

He was elected to the National Academy of Sciences and the

American Academy of Arts and Sciences in 1974.

In the mid-1970s Baltimore turned to research in molec-

ular immunology, establishing a major presence in that rapidly

developing field. As a prominent figure in the scientific com-

munity, Baltimore became outspoken about the potential risks

of genetic engineering. He was concerned that the rapidly

developing techniques of molecular biology might be mis-

used. In 1975 Baltimore initiated a conference in which scien-

tists attempted to design a self-regulatory system regarding

experiments with recombinant DNA. In the following year the

National Institutes of Health established a committee to over-

see federally funded experiments in the field of genetic engi-

neering. Baltimore became a key link between basic molecular

biology and the burgeoning biotechnologyindustry. In 1984

he was appointed founding director of the new Whitehead

Institute for Biomedical Research, which is affiliated with

MIT; he remained at this post until 1990. In that position

Baltimore made significant advances in the field of immunol-

ogy and synthetic vaccineresearch. He earned wide admira-

tion for forging dynamically amicable relations between the

two institutions, developing a high-powered young faculty

and molding the Whitehead into one of the world’s leading

institutions of its kind. Baltimore was a major influence in

shaping the Human Genome Project and is an outspoken

advocate of greater national investment in AIDS research.

In July 1990 Baltimore became president of Rockefeller

University, launching an energetic program of fiscal and struc-

tural reform to bring the university’s finances under control

and to provide greater encouragement for junior faculty mem-

bers. He resigned from the presidency at the end of 1991. At

the time he was caught up in a controversy that stemmed from

his support of a collaborator who had been charged with sci-

entific misconduct, but whose scientific honesty he had res-

olutely defended. Several years later the collaborator was

found to be innocent of all the charges raised against her.

Baltimore remained on the faculty of Rockefeller University

until 1994, when he returned to MIT as the Ivan R. Cottrell

Professor of Molecular Biology and Immunology, and then

Institute Professor.

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