AIDS scientists are studying viruses isolated from two people to find out if either of them are the source of a possibly more aggressive, drug resistant strain of HIV discovered in a local man.

Dr. David Ho, director of the Aaron Diamond AIDS Research Center said more tests are needed to determine if the strains from the three people are identical. Some findings may be available in a week, while others may take longer, he said.

“What we can’t prove is that this is a supervirus,” Dr. Ho told The New York Times in Monday editions. He explained it is not clear whether it caused rapid progression from infection to AIDS in the New York City man, whose name has not been released.

Last week, the man was reported to have contracted a strain of HIV that quickly transforms into AIDS.

Even if the strains were the same, Dr. Ho said, it still may not mean that a supervirus is spreading because there might be genetic factors in the man that made the virus more aggressive.

The research center has also began testing a virus isolated from a man who was infected with HIV before he became a partner of the New York man.

Another virus being studied is said to infect a San Diego patient who had it before the New York man was diagnosed.

Dr. Ho said portions of the virus’ genetic makeup resemble molecular pattern of the New York man’s virus.

Meanwhile, Massachusetts doctors have also treated several HIV patients with a resistance to some of the most commonly prescribed treatments, raising further concerns about a possible new, drug-resistant strain of the virus. Public-health officials around the country are closely monitoring the case to determine the extent of the threat.

The city health department is trying to trace as many of the New York man’s sex partners as possible, but he said that he has had many in recent weeks while using the drug crystal methamphetamine.

Only about a dozen of the man’s partners have been reached by the health department, said spokeswoman Sandra Mullin. The number that have forward and donated specimens for testing is unclear.