The New York Times - November 20, 1986
Lawrence K. Altman

The newest virus was identified in several West African patients suffering from AIDS in Sweden, according to Dr. Robert C. Gallo, a leading AIDS researcher at the National Cancer Institute. The new virus is designated SBL (for State Bacteriology Laboratory) 6669 V-2.

Dr. Gallo and the other AIDS researchers, Dr. Luc Montagnier of the Pasteur Institute in Paris and Dr. Myron Essex of the Harvard School of Public Health, hinted in lectures and a news conference that even more AIDS viruses might be found.

It is common to find more than one virus causing a particular disease. For example, three types of the polio virus can cause paralysis.

Discovery in Portugal

The new Swedish virus joins two others that are known to cause acquired immune deficiency syndrome. The one that is believed to cause the overwhelming majority of AIDS cases in the world is designated variously as HIV, HTLV-3 and LAV-1.

Earlier this year, Dr. Montagnier, working with researchers in Portugal reported the discovery of another virus, LAV-2, among people in West Africa. Yesterday, Dr. Montagnier said he and his collaborators had found the LAV-2 virus in at least six West African as well as in three European countries.

Neither the LAV-2 virus nor the new Swedish one has been found in the United States.

Thus for the moment, the new viruses do not appear to pose any peril in this country, the researchers said. But they also said further study was needed to determine the frequency of occurrence and where.

A fourth virus further complicates the picture. Dr. Essex reported earlier this year that his team had discovered that virus, HTLV-4, with collaboration of scientists in Africa.

Time for Assessment Needed

However, the HTLV-4 virus apparently has not caused disease among the about 300 people from whom it has been identified, Dr. Essex said yesterday. Thus, to some AIDS workers, HTLV-4, though it belongs biologically to the same family of retroviruses, is not truly an AIDS virus because it does not cause disease. These experts say that a much longer period of time is needed for assessment.

Dr. Essex has reported that the HTLV-4 virus is closely related to the STLV virus that he also helped discover and that infects monkeys in Africa.

Dr. Gallo spoke about the new virus in his Lasker award lecture and said that though a report of the new Swedish virus has not been published, its discoverers - Dr. Gunne Biberfield, Dr. Erling Norrby, Dr. Jan Albert and Dr. Eva Marie Fenyo - have cited it at scientific meetings. In an interview, Dr. Gallo said he was reviewing the Swedish paper for Science magazine.

All the AIDS and AIDS-like viruses of humans and animals are now under study to determine their similarities and differences, Dr. Gallo said.

An Enormous Spectrum

The viruses are believed to cover an enormous spectrum; some appear to be strongly infective, others seem to be weak. Some strains of the same type of AIDS virus barely infect cells under laboratory conditions, Dr. Gallo said, while other strains "run to" the cells.

"What makes one cause disease, another not, I don't know," Dr. Gallo said. But, he added, "The answer will come in 1987." He said he hoped scientists would find a particular gene that accounted for the difference.

New information is constantly evolving in this work, and Dr. Gallo also said Dr. Flossie Wong-Staal in his laboratory had proved the existence of a new gene, called R, in an extension of work done by Dr. Simon Wain-Hobson at the Pasteur Institute.

Dr. Gallo, Dr. Montagnier and Dr. Essex agreed that further research was needed to determine the speed with which the new AIDS viruses were being spread and the proportions of all AIDS infections caused by each virus.

Can Escape Detection

An important concern, the three researchers said, was that the new viruses can escape detection by the existing AIDS blood test.

Dr. Montagnier said LAV-2 had been detected in one unit of blood in the French blood bank system and that it had not been given to a patient.

Dr. Montagnier said in an interview that he and his collaborators had detected the LAV-2 virus in at least six West African countries: Cape Verde Islands, Guinea-Bissau, Mali, Senegal, Guinea and Ghana, as well as in France, Belgium and West Germany. Dr. Montagnier said researchers were searching for the LAV-2 virus in Central Africa where AIDS is epidemic.

Dr. Montagnier reported on 30 cases of LAV-2 infection. The cases involved 18 women and 12 men. For reasons scientists do not fully understand, the predominant route of spread of AIDS in Africa seems to be through heterosexual intercourse.

A few people seemed to have double infection, with LAV-1 and LAV-2.

Dr. Montagnier said preliminary research had shown that LAV-2 seems to grow better in primates than does the LAV-1 virus.

Has LAV-2 just appeared in Africa? "My guess is that it has been there for awhile," and was only recently recognized, Dr. Montagnier said.

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