Researchers create antidote to deadly bio-attacks

Tel Aviv, April 20 (IANS) Researchers seem to have found a way to protect against deadly chemical attacks, such as Tokyo subway sarin incident, that left 13 people dead and thousands injured or with temporary vision problems.

"The sarin attack in Tokyo in 1995 demonstrated that both the raw materials and know-how of producing deadly nerve agents are available to people outside government or military institutions," said Moshe Goldsmith of the Weizmann Institute of Science in Israel.

"We hope that our work would provide a prophylactic drug that will effectively protect the medical, police, and other teams that will have to act in a contaminated area following such an attack," said Goldsmith.

Today protection against nerve agents relies primarily on physical barriers such as gas masks and protective suits that can easily be breached, Goldsmith explained. Following exposure, people are treated with drugs that help with the symptoms but do not eliminate the nerve agent, the journal Chemistry & Biology reported.

Goldsmith and senior study author Dan Tawfik hope to change this, relying on the principles of evolution to produce a more efficient version of an enzyme that occurs naturally in all of us, according to a university statement.

Known as paraoxonase 1 (PON1), this enzyme was originally named for its ability to assist in the breakdown of the insecticide paraoxon. It is also involved in drug metabolism and detoxification. PON1 normally does counteract G-type nerve agents, including sarin, tabun, soman, and cyclosarin, but not well enough.

Tawfik's lab specializes in a technique called "directed enzyme evolution," in which they re-engineer the gene encoding a target enzyme, in this case PON1. The mutated versions are then put back into bacteria, which produce the enzymes for testing.

The goal was to end up with enzymes capable of detoxifying G-type nerve agents before those nerve agents could reach their target and cause harm. Those that passed the initial test went on to further rounds of evolution and testing.

After four rounds of evolution, the researchers obtained PON1 variants that worked up to 340 times better than those produced previously. Overall, the researches reported that the PON1 variants showed 40 to 3,400-fold higher efficiency than the normal enzyme in metabolizing the three most toxic G-type nerve agents.