Acknowledging what some other scientists have long claimed, two leading Harvard AIDS researchers have admitted a laboratory error in their published research about an AIDS-related virus in West Africa.

Both sides in the dispute agree the error does not alter the Harvard group's fundamental findings or call into question the existence of the virus, which is known as HIV-2 to distinguish it from the main AIDS virus, HIV-1.

Max Essex and Phyllis Kanki of the Harvard School of Public Health discovered evidence of an AIDS-like virus in a group of healthy Senegalese prostitutes in 1985. They labeled it HTLV-4 initially. The controversy began after they isolated the new virus and found it almost identical to another AIDS-like virus found in African green monkeys, SIV.

Both sides now agree that some of the human cells tested by Essex and Kanki must have accidentally become contaminated with monkey virus.

The allegation of the contamination, which has been raised repeatedly in the past two years, was published in a letter to the British scientific journal Nature by nine scientists from the New England Regional Primate Research Center in Southboro, Mass.

In a brief reply, Essex and Kanki said they "acknowledge the results of others and agree that certain isolates initially reported by us as HIV-2/HTLV-4 should be considered SIV unless proven otherwise." They said their ongoing studies use other independent isolates of HIV-2 and emphasized that the conclusions of their studies "remain unchanged."

An accompanying commentary in Nature by Carel Mulder, a professor at the University of Massachusetts Medical School in Worcester, said "it honors Essex and Kanki that they readily admit" that the contamination occurred. "Too seldom do researchers in this field retract data found to be erroneous."

The misidentification "will not alter the results of their seroepidemiological surveys," Mulder said.

Even critics acknowledge the essential validity of Essex's and Kanki's serological research in West Africa and their 1985 finding that healthy Senegalese prostitutes were infected with an AIDS-like virus closer to the monkey virus than to the AIDS virus.

HIV-2 has infected mainly West Africans so far. It has been reported in West African AIDS patients by scientists from the Pasteur Institute in Paris, though its potential for causing a second AIDS epidemic remains uncertain.

The first known case of AIDS caused by HIV-2 in the United States was recently identified in a West African visiting New Jersey.