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Findings on Monkey AIDS Virus Should Aid Vaccine Testing, Scientists Say

August 5, 1987

NEW YORK (AP) _ Researchers have deciphered the genetic code of a virus that causes AIDS in monkeys, an important step for research into human AIDS vaccines, scientists say.

The ″simian immunodeficiency virus″ strikes macaques, and its genetic details will let scientists develop and test macaque vaccines to gain insight into designing human vaccines against AIDS, researchers said.

The new studies also show the SIV resembles viruses linked to AIDS in humans, making its infection of macaques ″a rational animal model for AIDS vaccines,″ said one of the researchers, Flossie Wong-Staal of the National Cancer Institute.

While chimpanzees can now be infected with human AIDS virus, researchers said macaques are less expensive and more common, allowing experiments in more animals. In addition, chimps do not develop AIDS as macaques do.

Two papers in Thursday’s issue of the British journal Nature describe the long chemical sequences that make up the genes of SIV.

One paper deals with SIV found in macaques, and the other with SIV found in African green monkeys. Previous research suggests they are the same virus or very close relatives, said Pierre Sonigo of the Pasteur Institute in Paris, who co-wrote the macaque SIV paper.

The SIV found in green monkeys does not appear to make those animals sick, but it does cause disease when injected into macaques, said Genoveffa Franchini of the cancer institute, co-author of the paper on green monkey SIV. That suggests it is closely related if not identical to the SIV found in macaques, she said.

Both papers found SIV to be closely related genetically to a human virus called HIV-2, which some researchers link to AIDS in West Africa. It is more distantly related to HIV-1, the AIDS virus found in the United States and elsewhere, the paper on green monkey SIV reports.

In terms of genetic sequences, the green monkey SIV is about 70 percent identical to the West African virus and about 40 percent identical to the AIDS virus HIV-1, Wong-Staal said.

But the difference between the macaque SIV and the West African virus is greater than the variation found among samples of HIV-1, said the Pasteur Institute’s Sonigo.

That argues against the hypothesis that human AIDS evolved from recent infection of people by the monkey virus, he said, but more study is needed.

Now that scientists know the detailed genetic makeup of SIV, they can develop experimental vaccines against SIV and test them in macaques, he said. That work can guide AIDS vaccine development for humans, he said.

The macaque SIV paper was written by Sonigo and colleagues at the Pasteur institute and scientists at the New England Regional Primate Research Center, part of Havard Medical School.

The green monkey SIV paper was written by Wong-Staal, Franchini, M.S. Reitz Jr. and others at the cancer institute, as well as scientists in Italy and at Biotech Research Laboratory Inc. of Rockville, Md.

Previous research found close similarities between SIV and a virus called HTLV-IV, which had been found in cells from apparently healthy people. Some researchers have suggested that HTLV-IV is actually SIV that contaminated those cells in the laboratory.

A third paper in Nature deals with a gene called ″tat,″ which helps the AIDS virus replicate. Scientists found tat genes in samples of HTLV-IV, HIV-2, green monkey SIV and a virus called SBL-6669, which Swedish researchers found in a Gambian woman with a hampered immune system.

The tat gene from the AIDS virus also does its work in SIV and HIV-2, they reported.

The study shows the viruses share similarities, suggesting that strategies against the AIDS virus HIV-1 should work against HIV-2, said co-author Wong- Staal.