COLUMBUS, Ohio - A controversial experiment in which veterinary researchers at Ohio State University inject cats with the feline version of HIV and give them drugs will continue, university officials said Tuesday.

The federally funded study that involves giving the infected cats methamphetamines was postponed in June, when the lead researcher resigned after receiving death threats.

Michael Podell, an associate professor of veterinary clinical sciences and neurosciences at the university, was testing to see if the drugs speed the spread of the virus in cats. Many people with the virus that causes AIDS also abuse illegal drugs.

Podell, a 10-year employee of the university, left this summer for another job after he received thousands of angry e-mails from animal rights activists and his children were confronted at school, university spokesman Earl Holland said.

"He had been the topic of great harassment and a number of threats," Holland said. "But he also left to pursue a great career opportunity."

Holland said security measures taken after Podell was threatened will remain in place.

The five-year study of the infected cats is in its third year. The first results were published in June. They said methamphetamines make the virus spread 15 times faster in cat brain cells.

"This kind of animal research plays an important role in improving our understanding of how pathogens can disrupt human health," said the university's president, Dr. Karen Holbrook. "Projects such as this one facilitate the design of treatments for humans and animals alike against many deadly viral diseases."

The National Institute of Drug Abuse gave a $1.63 million grant for the study to the OSU Research Foundation.

Veterinary school and federal officials decided to continue the grant under the leadership of two other university researchers.

Protect Our Earth's Treasures, a Columbus-based animal rights organization, said protests against the experiments are planned Friday morning.

"This project is wasteful," said POET's director, Robin Russell. "Forty-two cats have already died. They are collecting the same data from humans."

The U.S. Department of Agriculture inspected Podell's laboratory in March and found no animal care violations.

Holland said the five-year study was to involve 120 cats. Less than 50 have been used so far.

Researchers at Ohio State last year used nearly 54,000 animals in experiments, including 47,582 rats and mice. Not all research animals are killed.