Point-of-care real-time DNA detection device for SARS-CoV-2 from clinical samples.

Since the global pandemic of SARS-CoV-2, people's health and the economic support of their countries have been seriously affected. It was necessary to develop a low-cost and faster diagnostic tool that allows the evaluation of symptomatic patients. Point-of-care testing and point-of-need testing systems have been recently developed to solve these drawbacks, providing accurate and rapid diagnostics at field level or at the site of outbreaks. In this work, a bio-photonic device has been developed for the diagnosis of COVID-19. The device is used with an isothermal system (Easy Loop Amplification based) for the detection of SARS-CoV-2. The performance of the device was evaluated in the detection of a SARS-CoV-2 RNA sample panel, showing an analytical sensitivity comparable to the reference method of quantitative reverse transcription polymerase chain reaction used commercially. In addition, the device was mainly built with simple and low-cost components; therefore, it is possible to obtain a high-efficiency and low-cost instrument. The device excites the sample to be analyzed with a semiconductor laser with a specific wavelength, thus triggering spontaneous emission of the fluorophore bound to the specific probe. The emitted fluorescence is suitably managed by using interferential filters. Under these conditions, a signal is registered and, depending on this level, defines the case as positive or negative. All the analysis is done autonomously inside the developed device through an integrated control system, and it is connected to a portable device to show the results wirelessly.

Protein repeats evolve and emerge in giant viruses.

Nucleocytoplasmatic large DNA viruses (NCLDVs or giant viruses) stand out because of their relatively large genomes encoding hundreds of proteins. These species give us an unprecedented opportunity to study the emergence and evolution of repeats in protein sequences. On the one hand, as viruses, these species have a restricted set of functions, which can help us better define the functional landscape of repeats. On the other hand, given the particular use of the genetic machinery of the host, it is worth asking whether this allows the variations of genetic material that lead to repeats in non-viral species. To support research in the characterization of repeat protein evolution and function, we present here an analysis focused on the repeat proteins of giant viruses, namely tandem repeats (TRs), short repeats (SRs), and homorepeats (polyX). Proteins with large and short repeats are not very frequent in non-eukaryotic organisms because of the difficulties that their folding may entail; however, their presence in giant viruses remarks their advantage for performance in the protein environment of the eukaryotic host. The heterogeneous content of these TRs, SRs and polyX in some viruses hints at diverse needs. Comparisons to homologs suggest that the mechanisms that generate these repeats are extensively used by some of these viruses, but also their capacity to adopt genes with repeats. Giant viruses could be very good models for the study of the emergence and evolution of protein repeats.