Finding may explain A.I.D.S. among ‘gays’

Press, 19 December 1986, Page 13

Finding may explain A.I.D.S. among ‘gays’

By

WARREN E. LEARY

NZPA-AAP Washington Scientists have discovered that the virus which causes A.I.D.S. can infect and persist in cells from the human rectum and colon, a finding that say may help explain the high incidence of the disease among people who practice anal sex.

Government researchers at the National Institute of Allergy and Infectious Diseases said they had shown for the first time the virus responsible for acquired immune deficiency syndrome could infect cells

other than those of the immune system. The researchers said their work was done in cell tissue cultures and they had yet to find the virus in colon or rectum cells taken direct from humans. But they say they have begun the project to get samples of these tissues from A.I.D.S. patients to see if the virus can be isolated.

Drs Malcolm Martin, Akio Adachi and others at the institute report in the January, 1987, issue of the “Journal of Virology.” that infected large bowel cells could be sources of continued viral spread to im-

mune system cells. About 70 per cent of the 28,098 A.I.D.S. cases reported to date in the United States are in homosexual males, many of whom practise anal intercourse. Health experts have said that the virus, which has been isolated in semen, could pass into the blood of the passive sex partner from tissue trauma caused by the act.

Dr Martin said in an interview that the latest findings could indicate another route of infection stemming from this sex practice.

“We have always wondered why gay men were selected out for A.1.D.5.,” Dr Martin said. “It now seems that it is not merely trauma. Colon and rectal cells appear sensitive to infection and can be infected directly.” Because it is difficult to culture normal colon and rectal cells long enough to test them, the researchers used cancerous forms of these cells for the tests. These types of cells grow for weeks or months in 'ultures. The researchers tested cancerous cells from a range of human tissues, including those from the

lung, pancreas and ovary, and found that only colon and rectum cells could be infected with the A.I.D.S. virus, they reported. They found the virus in. three of five cells samples from the colon and rectum. The virus previously has been found to infect white blood cells called T--4 lymphacytes, its primary target, and macrophages. T-4 lymphocytes are key cells that orchestrate the infection-fighting immune system. Their destruction by the virus drags down the rest of the system.

The researchers also said they found that the infected colon and rectum cells produce genetic material that is responsible for a protein called CD4. This protein, which itself has not been isolated from bowel cells, is found on the surface of T--4 and other immune cells that are targets of the virus. Later tests with normal colon and rectum cells also found this genetic material for CD4 coming from them, the researchers added. The protein is believed to help the virus recognise and bind to its target cells.