A photo from open sources Paper diagnostic tests soon time can change the technology for detecting infections. To demonstrate the effectiveness of an approach that includes DNA coating of paper jellyfish and other organisms, developers used it to identify two strains of Ebola virus. “It a new class of diagnostics and the most important practical application synthetic biology, – comments one of the developers Jim Collins (Jim Collins) from the Wiss Institute at Harvard. – This technology opens up a new generation of diagnostic tests. ” The technology is based on the ability to “print” (apply) DNA to paper. Then the paper strips are freeze-dried and further stored at room temperature. Key DNA sensitive element, “activated” when water is added. After “inclusion” paper changes color if it comes in contact with the target agent: for example, a segment of an Ebola strain or viral RNA, present in water. 
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A fragment of the DNA indicator binds to the genes of the target DNA, which causes the production of a signaling substance: a protein that gives jellyfish a green glow in ultraviolet light, or proteins from bacteria that cause discoloration visible to the naked the eye. The color of the paper indicates which of the target pathogens. detected. “We have expanded the range of litmus test options for biochemical reactions, ”Collins explains. – Do it it turned out to be very simple. “Collins colleague Keith Pardee (Keith Pardee) improved the test by adding non-naturally occurring genes switches (genetic switch), which do not give color however was changing unless a very specific target molecule present in samples. Switches in a strip of paper at the same time check samples for 24 different sections of viral RNA – this much more than would be possible using exclusively natural DNA sequences. So in In laboratory conditions, it was possible to distinguish between the versions of the Zaire strain Ebola virus (responsible for the West African epidemic) and Sudanese strain. During the tests, the paper test identified virus strain in 30 minutes, that is, this technology has surpassed more expensive and complex laboratory techniques that use antibodies. Collins estimates a new diagnostic test will cost only $ 21 (about 900 rubles) – this is for the most part the price a DNA sequence capable of detecting viral RNA. The cost of the basis of DNA indicators (of which there are 24 in the device) amounts to mere pennies – from 2 to 4 cents (less than 2 rubles). Assembling a paper diagnostic test takes scientists only 12 hours. In general, the new test has a lot of advantages. True, developers still have a lot of work to do prove the effectiveness of paper dough, determine its ability detect the minimum number of target molecules, percentage errors and false positive results. Generally, diagnostic test to confirm its full compliance. Oddly enough, but in the wake of new technology paper tests are just evolving: so, researchers created an indicator of Pseudomonas aeruginosa bacteria, often causing cystic fibrosis, as well as a diagnostic test for cancer diseases. New development opens up great opportunities for development of such – affordable and simple, able to work in field conditions – biosensors. Technology is not quite ready yet for practical use: it has yet to be finalized and to test. However, paper strips that can detect the virus is being developed for a possible use as a cheap and easy way to quickly identify infected people. The plans of Collins and his colleagues – the creation of other tests that identify genes resistant to antibiotics bacteria. The molecular structure can also be printed on fabric, so that a diagnostic test can be added to bandages and clothes medical personnel who will change color in contact with infected, who do not yet show pronounced signs illnesses. Collins group scientific article about invention, was published in the publication Cell.
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