VA scientist first to show viruses can cause cancer

A longtime VA scientist, Dr. Ludwig Gross was one of the great pioneers of cancer research and the father of modern retrovirology.

Gross, who served in the US Army Medical Corps during World War II, discovered the first two mammalian cancer viruses in the 1950s and was the first scientist to demonstrate that mammalian leukemia was transmitted by a virus. He showed that murine leukemia virus and parotid tumor virus could cause cancer when injected into laboratory species.

Both of these viruses are retroviruses. A retrovirus has RNA instead of DNA as its genetic material. The virus that causes AIDS, human immunodeficiency virus (HIV), is a type of retrovirus.

“Laid the foundation” for future scientific work

At first, some scientists questioned his findings, believing it unlikely that viruses could cause such a complex disease as cancer. But other scientists, inspired by his experiments, later came to similar conclusions. After his work was published, other viruses capable of causing solid or blood-borne tumors in mice were described by pioneering scientists such as Arnold Graffi, Charlotte Friend and John Moloney.

In 1974, Gross received the prestigious Lasker Award for his discovery of what became known as the Gross mouse leukemia virus. His work in the 1950s, the Lasker Foundation said, opened up the field of mammalian tumor virology and “laid the foundation for the later discovery by others of cancer-inducing viruses in animals of various species.” ranging from rodents to higher primates”.

The Lasker Foundation also said: “To Dr. Gross, who stood up to protracted skepticism, granted his discoveries with tenacious experimentation and insight, and who succeeded in changing the course of medicine, this medical research award fundamental Albert Lasker of 1974 is awarded.”

Escaped occupied Poland after the Nazi invasion in 1940

Gross was born on September 11, 1904 in Krakow, Poland to a prominent Jewish family. He was interested in medicine from an early age and studied for a medical degree at the Jagiellonian University in Krakow. He then trained in internal medicine at St. Lazar General Hospital, also in Krakow, in the early 1930s. Shortly after the Nazi invasion of Poland in 1940, he escaped from Poland occupied and traveled to the United States, where he studied tumor immunology at Christ Hospital in Cincinnati and enlisted as a captain in the US Army Medical Corps during World War II.

When the war ended, Gross was assigned to the Bronx Veterans Hospital in New York. He remained there after leaving the service and became the head of cancer research in 1946.

According to a biography of Gross written by Dr. Robert C. Gallo for the National Academy of Sciences, Gross got his big break in 1951 after attending a conference about a virus that could only infect nursing mice. Gallo, co-founder of the Institute of Human Virology, rose to fame in 1984 when he co-discovered HIV as the cause of AIDS.

Author of a reference work on the virology of tumors

When Gross returned to his lab and tried his filtered extracts on lactating mice instead of the adult mice he was using, Gallo wrote, he was able to transmit leukemia. This marked the first demonstration of virally transmitted leukemia in mammals, according to Gallo. Leukemia is a progressive disease in which the bone marrow and other blood-forming organs produce an increased number of abnormal cells. These cells suppress the production of normal blood cells, leading to anemia and other symptoms.

“It was far from generally accepted,” Gallo wrote. “Corn [Gross] found support from fellow researchers, especially Albert Sabin, a fellow Polish Jew who went on to develop oral polio vaccination. Eventually the virus, called Gross Passage A, was available to ship to other researchers. This virus, known as macroscopic leukemia virus, was the first mammalian retrovirus to be discovered. His discovery inspired other researchers to identify many other mammalian retroviruses, many of which expressed as leukaemias, lymphomas or sarcomas in their respective host species.

Eventually Gross accumulated enough data in his study of viruses to write a detailed monograph—Oncogenic viruses—the first history of tumor virology. Published in 1970, it became a standard reference work and marked the emergence of tumor virology as a distinct and legitimate field of study. It is considered a leading source book for early work in the discovery of carcinogenic viruses.

In 1999, Gross died of stomach cancer at the age of 94. The National Library of Medicine keeps a collection of his personal papers.

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