Dr. Shibasaburo Kitasato will appear next year as a portrait on a 1,000-yen bill. Dr. Kitasato established “serum therapy”. It was shown how to do it more than 130 years ago, but it still saves lives. (Kenji Tamura)

In September last year, when high school student, Mr. A was living in City B, he was bitten on the right hand by a venomous snake, Yamakagashi that he encountered near his home. Soon his hand was swollen and he couldn’t stop bleeding from the place of the bite.

He was treated at a hospital, but the “fibrinogen” in his blood, which is involved in hemostasis, was almost depleted. It was extremely dangerous.

The treatment method that we arrived at was serum therapy. An “antivenom” that neutralizes the toxins of Yamakagashi was made from serum from which blood cells were removed from the blood of horses, and was stored in various region.

Effect on Yamakagashi venom “Overwhelming”

When receiving an antivenom drip, fibrinogen levels quickly recovered. Mr. A was able to leave the hospital safely. Antivenom is a protein also known as an “antibody.”

According to Dr. Toru Hifumi, chief of the emergency medicine department at St. Luke’s International Hospital, which is mainly responsible for serum therapy treatment and research in Japan, there have been 45 cases of severe illness due to Yamakakashi bites since 1971, and five people, including a six-year-old child, have died. “There are other methods of treatment, but the therapeutic effect of antivenom is overwhelmingly high,” says Dr. Hifumi.

It was in 1890 that Dr. Kitasato published a paper on serum therapy under the joint name of Dr. Behring. Repeated injections of trace amounts of tetanus culture into rabbits allowed them to tolerate injections in higher than lethal doses, and the presence of antivenom in the serum became present, he said.

The principle of making the antivenom of Yamakagashi is the same. The collected venom is weakened and injected into the horse multiple times. Components that neutralize the venom are collected from the serum of horses and formulated.

Infected with a “new deadly virus” How to deal with it

Serum therapy also appears in the manga “Golgo 13”.

Golgo, who was on a cruise ship, accidentally infected with a new deadly virus from a monkey. He also onsets the disease himself, but finds a monkey in a warehouse that remains asymptomatic and determines that this monkey has antibodies in his body. Use monkey serum to get out of the predicament.

In modern times, “antibody drugs” that artificially produce antibodies using genetic engineering technology and use them for treatment are being applied in various fields. Opdivo, a cancer drug, and Actemra, a rheumatism drug, are prime examples.

Antibody drugs were also used to treat new coronavirus infections. A therapeutic drug was created based on the information on antibodies possessed by recovered patients, and it attracted attention in the United States, where it was used to treat then-President Donald Trump.

However, when the Omicron strain of the mutated virus, whose genetic information is very different from before, appears, the effect decreases significantly. The mainstream of treatment has changed to antiviral drugs such as “Paxlovid Pack”.

At the beginning of the emergence of the coronavirus, when there was no effective treatment, treatment with serum therapy itself was tried in China and other countries. However, its scientific efficacy has not been confirmed.

Serum therapy has strengths and weaknesses that are still used in active use.

Its strength is that it can counter many targets that cause disease.

In the case of pit vipers subject to serum therapy, it is estimated that there are about 100 types of venom components, and even if only one of them is suppressed, the symptoms may not be resolved. Serum therapy antivenoms can be dealt with collectively, because they contain diverse antibodies to a variety of toxins.

Most are not profitable

The weakness is that it is currently made from the serum of animals such as horses, so it is prone to side effects such as allergic reactions. It can lead to life-threatening anaphylaxis, so extreme caution is required when treating it.

Antibody drugs that do not use animal serum do not have such concerns. Researcher B and his colleagues at the National Institute of Infectious Diseases have begun research to develop antibody drugs.

Some antivenoms used in serum therapy are sold by pharmaceutical companies, but most of them are not profitable because of the small number of cases of use, and they have not been approved. The antivenom of Yamakagashi has also been used in the treatment as a study. There are only a few staff members involved, and they work on a volunteer basis.

They are preparing antivenoms to deal with the venoms of marine organisms such as the hab jellyfish and the stone fish. This is because global warming is expected to cause damage north of Kyushu that has not been seen before.

“The serum therapy developed by Dr. Kitasato is the starting point of modern immunology in terms of antibody discovery,” says Dr. C, an immunologist, “and the government should strengthen its support for serum therapy, which is currently used as a silver bullet, and support efforts as part of economic security, even if it is not profitable.”

Kitasato Shibasaburō (1853~1931) Born in present-day Kumamoto Prefecture. He studied in Germany and succeeded in cultivating pure tetanus bacteria under Dr. Robert Koch. Subsequently, serum therapy was developed. After returning to Japan, he established the private Kitasato Research Institute in 1914. He was reportedly a strong candidate for the first Nobel Prize.

If you have any comments or feedback, please send them to iryo-k@asahi.com with your name and contact information. (Kenji Tamura)