The first vaccine for feline immunodeficiency virus was approved for commercial production and veterinary use today by the U.S. Department of Agriculture.

The patented vaccine for this disease, which is a cat form of AIDS, has been licensed for manufacture to Fort Dodge Animal Health, a division of Wyeth. Patents for the vaccine are held by the University of California and the University of Florida.

The vaccine should be available to veterinarians by this summer.

"This vaccine offers the first effective protection for cats against this often fatal disease," said Niels Pedersen, director of the Center for Companion Animal Health and an international authority on retroviruses and immunologic disorders of small animals. "The success of the FIV vaccine also offers hope that eventually a vaccine will be developed that will effectively protect against AIDS in humans."

Pedersen and immunologist Janet Yamamoto, now a professor in the University of Florida's College of Veterinary Medicine, first isolated the feline immunodeficiency virus (FIV) in cats at UC Davis in 1986. Yamamoto began work on a vaccine for the virus at UC Davis and continued her research at the University of Florida, Gainesville. She has worked with researchers at Fort Dodge Animal Health for more than a decade to develop the vaccine.

"Formal approval of the vaccine is really a tribute to Dr. Yamamoto, who has doggedly persisted in pioneering this approach for an FIV vaccine," Pedersen said.

"We are delighted that many years of research are now coming to fruition and providing cat owners and veterinarians with a protective vaccine for FIV," added Larry Fox, director of technology transfer for UC Davis. Fox formerly was director of Corporate Molecular Biology at Abbott Laboratories, where he was involved in development of the first HIV assay and a subsequent recombinant DNA assay for HIV.

Research on vaccines for the different viruses that cause AIDS in cats, monkeys and humans continues at UC Davis, which has the distinction of being home to a veterinary school, medical school and a regional primate research center.

Feline immunodeficiency virus is transmitted from cat to cat mainly through bite wounds because the virus is present at high levels in the saliva. Like human AIDS, the virus attacks the body's immune system, making the animal susceptible to diseases and infections that usually would have little effect on an FIV-free animal.

Cats infected with FIV may remain healthy for five to 10 years before symptoms such as diarrhea, weight-loss, fever, swollen lymph nodes and chronic infections appear. Although infected cats may recover from their initial illness, they become lifelong carriers of the virus.

It's estimated that between 2 percent and 25 percent of the global domestic cat population is infected with the virus, according to the U.S. Department of Agriculture. Infection rates are highest in Japan and Australia and lowest in the United States and Europe. Outdoor roaming cats, older cats and cats with chronic ill-health are more likely to be infected. Aggressive free-roaming males, which are most likely to get into fights with other cats, are at greatest risk for contracting FIV.

FIV does not infect or cause disease in humans.

The newly approved vaccine is known as a "killed vaccine," made from an inactivated form of the FIV virus itself. The vaccine stimulates the protective immune response in the animal's body without the danger of inadvertently causing the viral disease. The new vaccine is composed of virus strains from two different types of FIV, one from North America and one from Asia.

In a study demonstrating the efficacy of the vaccine, cats received three doses of the FIV vaccine and a year later were exposed to a different strain of the virus. Sixty-seven percent of the vaccinated cats were protected against the virus, while 74 percent of the non-vaccinated cats became infected with FIV. Studies indicate that the vaccine provides protection against FIV for at least 12 months.