"Litmus test" for the diagnosis of Ebola and not only
Researchers specializing in synthetic biology at the Wyss Institute, part of Harvard University, have developed a fundamentally new platform for fast and cheap diagnostics of infectious diseases, functioning on the principle of a "litmus test". To demonstrate the effectiveness of the new approach, they successfully used it to identify two strains of the Ebola virus.
The key approach of the new technology is to apply the DNA sequence to discs made of filter paper, which are subsequently freeze-dried and stored at room temperature.
Applying a drop of water to such a disk reactivates DNA, which, by binding to a target molecule (for example, an Ebola virus RNA fragment), triggers a chemical reaction that leads to a change in the color of the paper base. As color indicators, a jellyfish protein that is fluorescent green in ultraviolet light or bacterial proteins can be used, the color change of which is registered with the naked eye. The color acquired by the paper disk after the application of the analyzed sample indicates the nature of the detected pathogen.
Genetic switches applied to the diagnostic disk during its production exclude the possibility of any color change in the absence of a highly specific target molecule. This makes it possible to simultaneously test for 24 different regions of viral RNA.
During the experiments, this made it possible to distinguish the synthetic version of the Zaire strain of the Ebola virus that caused the epidemic in West Africa from the synthetic version of another variant of the virus, known as the Sudanese strain.
The testing process takes 30 minutes, which is comparable to the time of more expensive and complex methods of analysis using antibodies. According to the head of the study, Professor Jim Collins, today the cost of such a sensor is determined by the cost of acquiring DNA sequences specific to viral RNA. However, when switching to industrial production, the synthesis of such DNA "on the spot" can reduce the cost of paper sensors to 2-4 cents apiece. Moreover, they do not need cooling during storage.
The developers note that in order to introduce the new test into clinical practice, it needs to be improved to ensure that the minimum concentrations of target molecules can be detected, as well as to minimize the likelihood of false-positive and false-negative results.
They also created prototype tests to identify the genes of antibiotic-resistant bacteria. The application of such indicators to the surface of the dressing material and clothing of medical personnel will allow timely detection of resistant strains of microorganisms and prevent the spread of nosocomial infections.
Article by Keith Pardee et al. Paper-Based Synthetic Gene Networks is published in the journal Cell.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of the Wyss Institute:
Synthetic biology on ordinary paper, results off the page.
Portal "Eternal youth" http://vechnayamolodost.ru27.10.2014