北京大「ワクチンなしでも流行制止」　コロナ治療薬開発に自信

【北京ＡＦＰ＝時事】中国・北京大学が開発中の新型コロナウイルス感染症（COVID-19）の治療薬が、感染症からの回復期間を短縮するだけではなく、短期的な免疫をもたらす可能性があることが明らかになった。（写真は中国・北京大学のゲノミクス研究機関、未来基因診断高精尖創新中心で検査を行う研究員）
　同大のゲノミクス研究機関「未来基因診断高精尖創新中心」の謝暁亮所長はＡＦＰの取材に対し、新薬は動物実験の段階で成功していると語った。投与から５日後にウイルス量が減少したという。１７日に米科学誌「セル」で発表されたこの治療薬は、新型コロナウイルス感染症から回復した患者６０人の血液から、謝氏のチームが分離した中和抗体を用いている。
　ウイルスに感染していないマウスにこの薬を投与したところ、新型ウイルスに接触しても感染せず、ウイルスが検出されることもなかったという。このことから謝氏は、医療従事者を数週間にわたって一時的に保護できる可能性があると述べ、その効果を「数か月に延長」することも期待していると述べた。
　現在世界では、新型コロナウイルス感染症に対して１００件以上のワクチン開発が行われている。しかし、ワクチン開発は多大な労力を必要とするため、謝氏は開発中の新薬が新型ウイルスの世界的流行を食い止める、より迅速で効率的な手段となることを期待していると語った。謝氏は「われわれはたとえワクチンがなくても、有効な治療薬でパンデミック（世界的な大流行）を制止できる」と述べている。
　さらに謝氏は「われわれの専門分野は免疫学やウイルス学ではなく、単細胞ゲノミクスだ。単細胞ゲノミクスのアプローチによって中和抗体を効果的に見つけることができると分かったときには沸き立った」と述べた。
　謝氏は、年内にはこの新薬を使用できるようになるとし、冬に起こるかもしれない流行に間に合うはずだとの見通しを示した。
　中国の保健当局によると、同国ではすでに新型コロナウイルスに対するワクチン候補５種類が臨床試験段階に入っている。だが、世界保健機関（ＷＨＯ）はワクチン開発には１年から１年半がかかると警告している。
　また同国では、回復した患者から採取した血漿（けっしょう）を用いた治療も７００人以上の患者で試みられている。当局は「治療の効果が非常に出ている」としているが、謝氏は「血漿は供給が限られている」と指摘。一方、謝氏らの開発中の薬で用いられている１４の中和抗体はすぐに大量生産が可能だと述べた。
　抗体を用いたウイルス感染症の治療は、エイズウイルス（ＨＩＶ）やエボラ出血熱、中東呼吸器症候群（ＭＥＲＳ）などで行われている。【翻訳編集ＡＦＰＢＢＮｅｗｓ】
〔ＡＦＰ＝時事〕（2020/05/20-13:08）

A Chinese laboratory has been developing a drug it believes has the power to bring the coronavirus pandemic to a halt.
The outbreak first emerged in China late last year before spreading across the world, prompting an international race to find treatments and vaccines.
A drug being tested by scientists at China's prestigious Peking University could not only shorten the recovery time for those infected, but even offer short-term immunity from the virus, researchers say.
Sunney Xie, director of the university's Beijing Advanced Innovation Center for Genomics, told AFP that the drug has been successful at the animal testing stage.
When we injected neutralising antibodies into infected mice, after five days the viral load was reduced by a factor of 2,500, said Xie.
That means this potential drug has (a) therapeutic effect.
The drug uses neutralising antibodies -- produced by the human immune system to prevent the virus infecting cells -- which Xie's team isolated from the blood of 60 recovered patients.
A study on the team's research, published Sunday in the scientific journal Cell, suggests that using the antibodies provides a potential cure for the disease and shortens recovery time.
Xie said his team had been working day and night searching for the antibody.
Our expertise is single-cell genomics rather than immunology or virology. When we realised that the single-cell genomic approach can effectively find the neutralising antibody we were thrilled.
He added that the drug should be ready for use later this year and in time for any potential winter outbreak of the virus, which has infected 4.8 million people around the world and killed more than 315,000.
Planning for the clinical trial is underway, said Xie, adding it will be carried out in Australia and other countries since cases have dwindled in China, offering fewer human guinea pigs for testing.
The hope is these neutralised antibodies can become a specialised drug that would stop the pandemic, he said.
China already has five potential coronavirus vaccines at the human trial stage, a health official said last week.
But the World Health Organization has warned that developing a vaccine could take 12 to 18 months.
Scientists have also pointed to the potential benefits of plasma -- a blood fluid -- from recovered individuals who have developed antibodies to the virus enabling the body's defences to attack it.
More than 700 patients have received plasma therapy in China, a process which authorities said showed very good therapeutic effects.
However, it (plasma) is limited in supply, Xie said, noting that the 14 neutralising antibodies used in their drug could be put into mass production quickly.
- Prevention and cure -
Using antibodies in drug treatments is not a new approach, and it has been successful in treating several other viruses such as HIV, Ebola and Middle East Respiratory Syndrome (MERS).
Xie said his researchers had an early start since the outbreak started in China before spreading to other countries.
Ebola drug Remdesivir was considered a hopeful early treatment for COVID-19 -- clinical trials in the US showed it shortened the recovery time in some patients by a third -- but the difference in mortality rate was not significant.
The new drug could even offer short-term protection against the virus.
The study showed that if the neutralising antibody was injected before the mice were infected with the virus, the mice stayed free of infection and no virus was detected.
This may offer temporary protection for medical workers for a few weeks, which Xie said they are hoping to extend to a few months.
More than 100 vaccines for COVID-19 are in the works globally, but as the process of vaccine development is more demanding, Xie is hoping that the new drug could be a faster and more efficient way to stop the global march of the coronavirus.
We would be able to stop the pandemic with an effective drug, even without a vaccine, he said.