The first superbug immune to all known viruses has been obtained in the laboratory: it is a strain of Escherichia coli modified through synthetic bioology, which also incorporates two safety measures that prevent the microorganism from surviving in nature and also nullify the risk that the modified genetic material can spread to other organisms. The result, from research led by Harvard Medical School in Boston, was published in the journal Nature and promises to reduce the threat of viral contamination, which often costs millions of dollars, when bacteria are exploited to produce medicines such as insulin and other substances, such as biofuels.
The key to the success of the researchers led by Akos Nyerges lies in the transport RNAs, or tRnas: molecules that have the task of reading the information contained in the DNA and transporting the right amino acid to the proteins under construction. In this case, the study authors replaced the correct tRNAs with ‘cheaters’, which insert the wrong amino acids. Consequently, when a virus invades the bacterium to force it to make its own proteins, the fake tRnas misread the instructions provided: the result is malfunctioning proteins, which prevent the virus from replicating.
The superbug also incorporates two different security measures. The first prevents the modified genetic material from being transferred to another organism, the so-called ‘horizontal gene transfer’, a phenomenon that often occurs in nature. In fact, the modified DNA of the microbe, as well as its false tRnas, would have no meaning in another organism, leading also in this case to the production of unusable proteins. Furthermore, the researchers made the strain of Escherichia coli dependent on a laboratory-built amino acid that does not exist in nature: if a bacterium were to escape it would die immediately, so no human being or other creature is at risk of being infected by a superbug.
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