Word: strains
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Dates: during 1970-1979
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...Chief Leonid Brezhnev, announced plans for quick resumption of the long-stalled talks on U.S.-Soviet arms limitations (see following story). But at the same time, in line with Carter's conviction that U.S. foreign policy ought to show more concern for human rights, Washington seemed willing to strain what might yet be a honeymoon of sorts with Moscow. The Administration issued some harsh public criticism of the internal affairs of East bloc countries...
...very large safety factor is added by the provision in the present Guidelines for biological containment. All work with mammalian DNA must be carried out only in an EK2 strain, which has a drastically impaired ability to multiply, or to transfer its plasmid, except under very special conditions provided in the laboratory...
...this connection, I would question the specification, in the Guidelines that an EK2 strain must have a survival frequency of less than 10-8 under natural conditions (interpreted by the committee as residual viability after 24 hours). Just as infection can be dramatically cured by a bacteriostatic antibiotic, such as chloramphenicol, as well as by a bactericidal one, such as penicillin, so the inability of an EK2 strain to multiply in the gut would be sufficient to ensure its rapid disappearance, even if it did not rapidly commit suicide. The important question, requiring extensive investigation, is not the rate...
...thus see that with a strain known to have added the gene for a potent toxin a serious laboratory infection requires the compounding of four low probabilities. With strains from shotgun experiments we have a fifth, very low probability, already mentioned: that an apparently harmless mammalian tissue will yield a dangerous product...
...risks thus seem very much smaller than the public has been led to believe. Nevertheless, it is important to keep all the probabilities low. For example, even if a toxin-producing strain could survive only very briefly in the gut, a large enough dose might meanwhile cause disease. Hence a major benefit from the current discussion could be the requirement that those working in this area learn and use the standard techniques of medical microbiology, at least until we have acquired much more experience...