Reappraising AIDS Vol. 3, no. 4

VOUE3 UBReaAPRILs199

VOLUME 3, NUMBER 4

AIDS

APRIL 1995

Kaposi's, Viruses, & Poppers
By Tom Bethell

Perhaps the most remarkable development of recent
months has been the announcement of a probable new
cause of Kaposi's sarcoma. At the outset, this was the
hallmark AIDS disease-the "gay cancer" of the early
1980s. Now, researchers believe it is caused not by HIV
but by another virus. Lawrence K. Altman's page-one
New York Times report on the claimed discovery, by a
husband and wife team at Columbia University, did not
mention HIV at all.[1] Lisa Krieger began her article in
the San Francisco Examiner: "New research suggests that
Kaposi's sarcoma, a potentially deadly disease long
thought to be caused by HIV, is instead caused by a
type of sexually transmitted herpes virus that preys on
people with AIDS."[2]
Yuang Chang and Patrick S. Moore of Columbia used a
new technique (representational difference analysis) to
identify DNA fragments in Kaposi's tissue. These resemble
Herpes sequences, but actual virus has not yet been isolated or cultured. What is suggestive is that the
sequences have been found both in AIDS-related
Kaposi's, and in the traditional, more benign form afflicting elderly men,
Four days after his first story, Dr. Altman wrote a second, asking (but not answering) a number of questions
about the relationship between this new agent and HIV.
[3] I asked Harold Jaffe, chief of AIDS research at CDC,
some of these same questions, and some that were new.
"If this new agent is assumed to be the cause of
Kaposi's, what role if any does HIV play in the development of KS?"
"Well, the answer is we don't know," Jaffe replied. "But
certainly the risk of KS is much higher in people with HIVrelated immunosuppression; about 300 times higher. That
would either suggest that HIV-infected people have a
higher rate of co-infection with this other virus, or there is
something specific to HIV that increases the risk of KS. It
is certainly possible that HIV and the putative KS virus
could be working in a synergistic way."
"How confident are you that this new agent is the
cause of KS?"
Since the initial announcement, Dr. Jaffe said, new
information, presented at a conference in Washington,
"showed that the same viral sequences were detected

in different forms of KS-not just HIV-associated but in
classical KS, and in African KS. I think this leaves us with
two possibilities. One is that this is simply an opportunistic
infection that likes to grow in this kind of tissue; or it is the
cause. At this point we can't say which of the two it is,
but I think it is certainly a good candidate to be the
cause."
"Lawrence Altman asked why the percentage of AIDS
patients with KS has declined in the last ten years."
"We don't know. That's been one of the mysteries.
One possibility is that, if there is another virus (and let's
say it's transmitted sexually), it may be that gay men
have changed their sexual practices and so the rate at
which they have been exposed to this new virus has
decreased as well."
"Does the CDC believe that nitrite inhalants play any
role in KS?"
I don't think we can exclude that possibility. When
you look at the epidemiology, what you have to explain
is why Kaposi's is so much more common among gay
men than among other HIV-infected persons. With the
finding of this new agent, the answer may be as simple
as: This new viral infection is much more common in gay
men. Another possibility is that there is something about
the lifestyle of gay men that is putting them at increased
risk; and nitrite-inhalant use is certainly one thing that
separates gay men from other sexually active people. I
don't think the evidence for nitrites being a co-factor is
very strong, though."
"Does the CDC say anything about the health effects
of nitrite inhalants?"
"We haven't studied them in any context other than
AIDS. We studied them early in the epidemic, with a
question whether they were actually the cause of AIDS.
Which of course they weren't. We were left with the
question: Could they explain something like Kaposi's sarcoma? I personally think that is not the explanation but I
don't think we can rule it out."
Harry Haverkos, director of the office of AIDS at the
National Institute on Drug Abuse, has long believed that
AIDS-related Kaposi's is caused by nitrite inhalants, or
"poppers." A muscle relaxant, they were originally pre