On the AIDS trail: work continues on test, cure, vaccine.

With AIDS research pushing ahead in fits and starts, the Scientists' Institute for Public Information (a nonprofit organization funded by private foundations, corporations and the media) held a press seminar in New York last week to highlight some of the starts. Among the topics: impediments to a vaccine; a treatment being tested in France; and a new AIDS test from England.

Several of the scientists at the meeting expressed the hope that the implicated virus doesn't easily cause the disease. "Clearly there are more infected people than sick people," said Luc Montagnier, who with his colleagues at the Institut Pasteur in Paris reported the first isolation of an AIDS-related virus (SN:5/21/83, p. 324). But once the virus does take up residence, the important question in terms of a vaccine becomes what the body does about it.

That the body develops antibodies to this virus is well known; the key is whether any of them are capable of neutralizing the virus. In his studies, says Montagnier, he has found low levels of neutralizing antibodies in some AIDS patients. "They may confer some type of protection," he says. Robert Gallo of the National Cancer Institute in Bethesda, Md., who was scheduled to attend the meeting but pulled out at the last minute, two weeks ago described finding neutralizing antibodies. "We don't know what practical aspects will come out of it," he told SCIENCE NEWS. Lac of neutralzing antibodies would have severely dimmed the prospects of a vaccine, he says, but their presence "does not [necessarily] mean that a vaccine can be produced."

Differences from virus to virus may stall the development of a vaccine against AIDS. Montagnier described a 20 percent variation in the gene that codes for the virus's protein envelope, a likely vaccine candidate. "This raises an important question," he says -- whether protection against one virus will protect against a slightly dissimilar one.

There is theoretical basis for good news in the prospect of natural immunization. "The number of hemophiliacs who have gotten AIDS is a tiny percentage of those who have antibodies," observes Robin A. Weiss of the Institute of Cancer Research in London, England. Live virus in the blood products hemophiliacs receive may have somehow been killed, and, says Weiss, "it might actually be immunizing them."

Weiss and his colleagues have developed a second-generation blood test that they hope will solve some of the problems of the first-generation test, about to be aproved (SN: 1/19/85, p. 36). The "old" test sometimes gives falsely positive and falsely negative results, a problem Weiss feels can be avoided with his test. In the first-generation test, blood serum is run past immobilized virus parts; antibody present will stick and can be detected with a second antibody.

In the British test, first described in the Sept. 1, 1984 LANCET, blood serum and laboratory-prepared radioactive antibodies to AIDS virus are incubated with viral pieces. If there is antibody to AIDS in the blood serum, it will compete for binding sites, and less of the easily measurable radioactive antibody will tsick to the virus. "We don't think we're getting any false positives or false negatives," says Weiss.

Jean Claude Chermann of the Institut Pasteur described an antiviral drug called HPA-23, one of several treatments being evaluated for AIDS. The drug has apparently halted the syndrom in a young French hemophiliac who began receiving treatment in May 1983. The drug has side effects -- it has to be temporarily halted when too many platelets were destroyed -- but since treatment ended in December 1983, the French researchers haven't been able to isolate the virus from the boy's blood, and he is now back at school.

"That doesn't mean we're curing the patient," Chermann cautions. "We're inhibiting one component of the disease." He and his colleagues are now trying the treatment on 33 other AIDS victims.

But there's still a long way to go. Noted luncheon speaker Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases, "Knowing all the scientific facts does not necessarily clarify the confusion.