Secrets of the HIV Controllers


By Bruce D. Walker B. D. ウォーカー
English 日本語 日本語
One day in early 1995 a man named Bob Massie walked into my office at the outpatient clinic of Massachusetts General Hospital in Boston. Massie told me he had been infected with HIV—the virus that causes AIDS—for 16 years and yet had never shown any symptoms. My physical examination confirmed he was healthy, in stark contrast to all other patients I saw that day. At that time, a new combination of drugs was being tested that would eventually slow the progressive decline in immune function that HIV caused. In 1995, however, most people who had been infected with HIV for a decade or more had already progressed to AIDS—the stage marked by the inability to fight off other pathogens. The young man standing before me had never taken anti-HIV medication and strongly believed that if I learned the secret to his good fortune, the information could help others to survive what was then generally thought to be a uniformly fatal disease.  1995年初めのある日,マシー(Bob Massie)という男性が,ボストンのマサチューセッツ総合病院にある私の外来診察室にやってきた。マシーは,自分は16年前,エイズを引き起こすヒト免疫不全ウイルス(HIV)に感染したが,いまだに何の症状も出ていない,と言った。診察してみると確かに彼は健康で,その日私が診た他の患者とはまったく違っていた。
Massie was born with hemophilia, a blood-clotting disorder. In those days, nearly all hemophiliacs were HIV-positive because they were infused repeatedly with blood products agglomerated from thousands of donors—none of whom were screened for HIV until the mid- to late 1980s. (Today hemophiliacs receive artificial clotting factors, which pose no risk of HIV contamination.) Some of Massie’s blood samples that had been stored for a study revealed that he had contracted HIV in 1978. Yet every test I conducted on him or his stored samples showed that the amount of virus in his blood was vanishingly small and that his immune responses seemed as strong as ever.  マシーは血友病という,血液凝固因子に異常がある疾患を持って生まれた。当時は多くの血友病患者がHIVに感染していた。彼らは血液製剤を繰り返し投与されるが,それは何千人もが提供した血液から作られたものだ。1980年代半ばから後半になるまで,提供者の誰ひとりとしてHIVのスクリーニングを受ける機会はなかった(現在,血友病患者にはHIVのリスクのまったくない人工凝固因子製剤が投与されている)。
I was stunned. This was the first time I had ever come face to face with a patient whose body appeared to be controlling HIV on its own and had been doing so for a decade and a half. Massie, as it turned out, was not alone. Investigators in California, Maryland, Italy and France had all come across similarly unusual individuals in the early 1990s and were studying them intently. We eventually determined that these extraordinary people divided into two main groups: one set of “long-term nonprogressors,” whose bodies were able to fight off an HIV infection for an extra long time but who ultimately became ill, and a much smaller group of even more astonishing “elite HIV controllers,” who, like Massie, simply did not develop AIDS year after year after year despite never having taken any anti-HIV medication.  これは衝撃だった。身体が自力でHIVを抑え込み,その状態を15年以上も維持しているような患者と出会ったのは,私はそれが初めてだった。だがその後,そうした感染者はマシー以外にもいることがわかってきた。1990年代初めには,研究者たちはカリフォルニアやメリーランドで,またイタリアやフランスで,同じように特異な人々に出会い,彼らについて詳しく研究するようになっていた。
Somehow the elite controllers maintain extremely low—or even undetectable—levels of virus in their blood. If scientists can figure out how these rarest of rare individuals can pull off such a feat, they may learn how to create an effective vaccine or develop therapies that strengthen a patient’s immune system, as opposed to just attacking the virus with drugs.  エリート・コントローラーの体内ではどういうわけか血中のウイルス量が極めて低く維持されており,検出できないことさえある。こうした類まれな人々の体内でどうしてそんなことが可能になっているのかがわかれば,単に薬でウイルスを攻撃するのではなく,患者の免疫系を強くする効果的なワクチンや治療法を生み出すことができるかもしれない。