Important note: Information in this article was accurate in 1984. The state of the art may have changed since the publication date.
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Wall Street Journal - August 14, 1984
Jerry E. Bishop, Staff Reporter of The Wall Street Journal
The debt was incurred when a lethal cat disease called feline leukemia helped pinpoint a human leukemia virus as a probable cause of human AIDS, or acquired immune deficiency syndrome. Now, scientists say AIDS research is helping in the struggle against feline leukemia.
"Cats have given their lives for humans for years, so it's about time we did something for them," says Mary Burr Fristachi, a Brooklyn artist who lost three of her five cats to feline leukemia.
Feline leukemia is one of the most common -- and most dreaded -- cat diseases. Up to a million of the nation's 52 million pet cats are expected to die of it. Once loose in a household or a cattery, it can decimate the cat population.
In 1945, Scottish scientists discovered that the disease is caused by a virus. At the time, scientists believed that animal cancer viruses were transmitted only "vertically," that is, from parent to offspring through the genes. But in the late 1960s, William D. Hardy of Memorial Sloan-Kettering Cancer Center developed a diagnostic test for feline leukemia that enabled scientists to study the pattern of the leukemia virus's spread among cats. In 1973 they reported that feline leukemia is contagious -- it spreads "horizontally" from cat to cat, via saliva and possibly through urine and mother's milk.
Contact has to be "close and intimate," says Dr. Hardy. Cats that groom each other and share the same feeding bowls and litter pans are the susceptible ones. The virus can also be spread by blood transfusions.
(Scientists have found no evidence that the cat virus is dangerous to humans. But, Dr. Hardy, who owns three cats, says he believes children and pregnant women shouldn't be exposed to cats harboring the virus.)
Most cats can develop an immunity to the virus, or seem to be infected only temporarily. Those that become chronically infected will initially seem healthy but die within three years. Researchers also noticed that only about a fifth of chronically infected cats developed leukemia. The remainder succumbed to a host of other ailments, including anemias, chronic infections, pneumonias and nonhealing wounds. These ailments suggested the cats' immune systems were being suppressed, making them vulnerable to microbes that ordinarily wouldn't cause serious disease.
When the human AIDS epidemic broke out three years ago, scientists noticed that the characteristics of feline leukemia were strikingly similar to the characteristics of AIDS. They began to speculate that AIDS too might be caused by a virus.
Robert C. Gallo, a virologist at the National Cancer Institute, and his colleagues here and in Japan had proved that a human virus was the cause of a rare human leukemia called T-cell leukemia. If a virus could cause both leukemia and immune suppression in cats, then perhaps this human leukemia virus might also be causing AIDS. The scientists began checking the blood of AIDS victims for signs of infection by the human T-cell leukemia virus, or HTLV.
At the same time, Max Essex, a veterinarian at the Harvard School of Public Health in Boston, found that the feline leukemia virus did indeed cause a feline version of AIDS, nicknamed FAIDS.
Recently, Dr. Gallo and his colleagues reported evidence that human AIDS is caused by a virus related to, but separate from, HTLV. Scientists are now trying to see if the same is true in feline leukemia/FAIDS.
"Research efforts on HTLV and feline leukemia are cross-fertilizing each other and should make it more likely that diagnostic tests and vaccines will be available far earlier than would ordinarily be the case," says Dr. Essex.
The cat researchers are several steps ahead of AIDS researchers. Dr. Hardy's diagnostic test has been available for several years. And earlier this year, a new diagnostic test for the feline leukemia virus was introduced by TechAmerica Group Inc., an Elwood, Kan., producer of veterinary products. The test can be performed by a veterinarian in about 20 minutes at a cost to the cat owner of about $15.
A team of immunologists headed by Richard Olsen at Ohio State University is completing work on another feline leukemia vaccine. These scientists had to overcome a problem that may face researchers into AIDS. Traditionally, explains Lawrence Mathes, one of the Ohio State scientists, vaccines are made by either killing or weakening the virus so that when administered it can stimulate the body to build up an immunity without causing disease. This failed to work in feline leukemia/FAIDS. The killed virus vaccine was ineffective; the weakened virus vaccine caused leukemia.
The scientists solved this by infecting feline cells in the test tube with the virus and then extracting the proteins that the cells released. When these proteins were used as a vaccine, 87% of the vaccinated cats didn't contract the disease after being bombarded with the virus.
The Ohio State vaccine has been turned over to Norden Laboratories, the veterinary subsidiary of SmithKline-Beckman Corp., the big drug maker. Norden is in the final stages of testing the vaccine and expects to seek federal approval soon to market it.
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