Corona testing in 30 minutes without requiring a technician: Nihon University with Yoshino Shiono - available in autumn

Recently Nihon Keizai Shimbun Electronic Edition reported the following:

技師不要30分でコロナ検査　日大や塩野義、秋にも

新型コロナ 経済 政治

2020/6/22 1:00日本経済新聞　電子版

専門の技師や検出器を使わず、30分程度で新型コロナウイルスを判定する検査法が実用に向けて動き出す。日本大学の桑原正靖教授らがつくったウイルス検査で、月内に塩野義製薬と量産向け検査キットの開発でライセンス契約を結ぶ。インフルエンザのように病院で医師や看護師が検査してすぐ結果を知ることもできる見通しだ。

塩野義は検査キットが診断に使えると判断すれば、厚生労働省に薬事承認を申請し、今秋の実用化を目指す。

政府の国家安全保障局（NSS）も利用法を検討中だ。政府は夏から海外との往来を緩和する予定で出入国時のPCR検査を条件にしている。検査能力が往来数の制約になるため、なかなか増えないPCR検査以外の手法を探していた。今回の検査法が確立すれば空港で短時間に大量の検査ができると期待している。

新たな検査法は桑原教授らが考案した「SATIC法」を応用した。95度で約2分間加熱した唾液を試薬に入れると、新型コロナを検出した場合に20～25分で変色する技術で、目視で感染の有無を判定できるという。

PCR検査と違い、高度な制御装置や検出器、練度が高い技師の操作は不要になる。PCR検査は検体の採取から搬送、検査までで3～5時間近くかかるのに対し、30分程度で済む。

PCR検査はウイルス量の多い鼻や喉の奥の粘液を採取することが多いが、発症から9日以内の場合は唾液の使用が認められた。新方式も採取が簡単な唾液を想定しており、検査の業務にあたる人の感染リスクも減る。

ウイルスのRNA（リボ核酸）を検知して判定するのはPCR検査と同じだ。PCR検査の場合は検知しやすくするために専用の機械と試薬でRNAからつくったDNAを増やす必要がある。新方式はこの工程が必要ないため大幅に時間や手間を省けるという。

試薬には特定の配列をもつRNAに結合する環状DNAを使う。それが新型コロナのRNAに結合して「グアニン四重鎖」と呼ぶ特殊な立体構造のDNAができる。そのDNAと試薬中の「ナノ磁性ビーズ」と呼ぶ分子が結合して凝集すると変色する。直接、RNAを検知するのではなく、別に検知しやすいDNAをつくることで判定が出やすくなる仕組みだ。

研究は日本医療研究開発機構（AMED）などの助成を受けている。日大と東京医科大は5月、共同で特許も出願した。

国内のPCR検査能力は現在、1日最大2万8千件。実施数は1万件を下回る。発熱などの症状があり、医師が必要と判断した人に原則として検査を限っている。このままでは感染の「第2波」が発生した際に検査が追いつかない恐れがある。

夏に緩和する海外往来も、当面はPCR検査体制の制約で最大でも1日250件だけだ。来夏には東京五輪・パラリンピックがあり、選手や大会関係者、報道機関など10万人規模の来日がある見通しだ。経済再開の規模をウイルス検査の能力が左右する可能性も指摘されている。

Translation

Without the need for a specialized technician or detector, a test method that could confirm the new coronavirus in about 30 minutes was moving towards practical use. With a virus test created by Professor Masayasu Kuwahara and others at Nihon University, a license agreement was signed with Shionogi Pharmaceutical Co., Ltd. to develop a test kit for mass production within a month. It was expected that, just like dealing with a flu in a hospital, doctors and nurses could be able to see the results quickly after an examination.

If Shionogi decided that the test kit could be used for diagnosis, it would apply for regulatory approval from the Ministry of Health, Labor and Welfare and aimed at commercialization this fall.

The government's National Security Agency (NSS) was also considering how to use it. The government planned to ease the traffic to and from overseas starting this summer, and it required PCR tests at the time of entry and exit. Because the test capacity was constrained by the traffic volume, the government was looking for a method other than the PCR test which was difficult to increase easily. If this checking method was established, it was hoped that a large amount of checking could be possible in a short time at the airport.

The new checking method applied a "SATIC method" devised by Professor Kuwahara and others. It was said that if the reagent was put into saliva that was heated at 95 degrees for about 2 minutes, it would change color in 20 to 25 minutes if a new corona was detected, so the presence or absence of an infection could be determined visually.

Unlike PCR testing, it did not require the operation of sophisticated control equipment, nor detectors and highly trained technicians. Compared to the PCR test that took about 3 to 5 hours,  it took about 30 minutes from sample collection to transportation and examination.

The PCR tests often collected mucus deep inside the nose and throat which had a high amount of virus, and also had to collect the saliva within 9 days of the appearance of the symptom. While the new method also envisioned a simple collection of salvia, but it reduced the risk of infecting people who performed the checking.

The detection of viral RNA (ribonucleic acid) was the same as in the PCR test. In the case of PCR testing, to make it easier to detect, it required dedicated machine and needed to increase the amount of DNA made from RNA with a with reagent. The new method did not require this process, which could save a lot of time and effort.

Circular DNA that bound to RNA with a specific sequence was used as a reagent. It bound to the RNA of the new corona to form DNA with a special three-dimensional structure called "Guanine quadruplex". When the DNA and molecules in the reagent called "nanomagnetic beads" bound and aggregated, its color changed. Instead of directly detecting RNA, making a DNA that was easy to detect made it easier to make a judgement.

The research was supported by the Japan Agency for Medical Research and Development (AMED). In May, Nihon University and Tokyo Medical College also applied for a patent.

Currently, the maximum PCR test capacity in Japan was 28,000, yet the number of tests done was less than 10,000. As a general rule, the testing was restricted to those who had symptoms such as fever and those who were deemed necessary by a doctor. If this continued, the test might not catch up when the "second wave" of infection occurred.

The number of overseas trips, which would be eased in this summer, was limited to 250 at the most per day for the time being due to restrictions on the PCR test system. There would be the Tokyo Olympics and Paralympics next summer, and it was expected that there might be 100,000 visitors to Japan including athletes, tournament officials, and the news media. It had also been pointed out that the scale of the economic resumption might be affected by the ability of virus checking.

               It is nice to know that Japan has developed a new method to check for the new virus. Without the assistance from a specialized technician or a detector, a test on the new coronavirus could be done in about 30 minutes.