ABSTRACT
Virus transmission is affected by population density, social distancing, and vaccination. This has been simulated only by mathematical models. Here, we report the first experimental model to mimic herd immunity to a human coronavirus using a microfluidic device filled with host cells. The device consists of 444 microchambers filled with susceptible (S0), infected (I0), and unsusceptible (U0) cells at specific ratios. The transmission rate and reproduction numbers were directly proportional to S0 and I0 and inversely proportional to U0. Herd immunity was achieved when the proportion of U0 was at 80% in a fixed number of uninfected (S0+U0) cells. These results were consistent with those from a mathematical model. The device can be used for predicting virus transmission. One-Sentence SummaryWe present the first experimental model enabling the simulation of herd immunity in a microfluidic device filled with host cells to human coronavirus.
ABSTRACT
BRAF inhibitors (e.g., vemurafenib) are widely used to treat metastatic melanoma with the BRAF V600E mutation. The initial response is often dramatic, but treatment resistance leads to disease progression in the majority of cases. Although secondary mutations in the mitogen-activated protein kinase signaling pathway are known to be responsible for this phenomenon, the molecular mechanisms governing acquired resistance are not known in more than half of patients. Here we report a genome- and transcriptome-wide study investigating the molecular mechanisms of acquired resistance to BRAF inhibitors. A microfluidic chip with a concentration gradient of vemurafenib was utilized to rapidly obtain therapy-resistant clones from two melanoma cell lines with the BRAF V600E mutation (A375 and SK-MEL-28). Exome and transcriptome data were produced from 13 resistant clones and analyzed to identify secondary mutations and gene expression changes. Various mechanisms, including phenotype switching and metabolic reprogramming, have been determined to contribute to resistance development differently for each clone. The roles of microphthalmia-associated transcription factor, the master transcription factor in melanocyte differentiation/dedifferentiation, were highlighted in terms of phenotype switching. Our study provides an omics-based comprehensive overview of the molecular mechanisms governing acquired resistance to BRAF inhibitor therapy.
ABSTRACT
BRAF inhibitors (e.g., vemurafenib) are widely used to treat metastatic melanoma with the BRAF V600E mutation. The initial response is often dramatic, but treatment resistance leads to disease progression in the majority of cases. Although secondary mutations in the mitogen-activated protein kinase signaling pathway are known to be responsible for this phenomenon, the molecular mechanisms governing acquired resistance are not known in more than half of patients. Here we report a genome- and transcriptome-wide study investigating the molecular mechanisms of acquired resistance to BRAF inhibitors. A microfluidic chip with a concentration gradient of vemurafenib was utilized to rapidly obtain therapy-resistant clones from two melanoma cell lines with the BRAF V600E mutation (A375 and SK-MEL-28). Exome and transcriptome data were produced from 13 resistant clones and analyzed to identify secondary mutations and gene expression changes. Various mechanisms, including phenotype switching and metabolic reprogramming, have been determined to contribute to resistance development differently for each clone. The roles of microphthalmia-associated transcription factor, the master transcription factor in melanocyte differentiation/dedifferentiation, were highlighted in terms of phenotype switching. Our study provides an omics-based comprehensive overview of the molecular mechanisms governing acquired resistance to BRAF inhibitor therapy.
ABSTRACT
Face masks are one of the currently available options for preventing the transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has caused the 2019 pandemic. However, with the increasing demand for protection, face masks are becoming limited in stock, and the concerned individuals and healthcare workers from many countries are now facing the issue of the reuse of potentially contaminated masks. Although various technologies already exist for the sterilization of medical equipment, most of them are not applicable for eliminating virus from face masks. Thus, there is an urgent need to develop a fast and easy method of disinfecting contaminated face masks. In this study, using a human coronavirus (HCoV-229E) as a surrogate for SARS-CoV-2 contamination on face masks, we show that the virus loses its infectivity to a human cell line (MRC-5) when exposed for a short period of time (1 min) to ozone gas produced by a dielectric barrier discharge plasma generator. Scanning electron microscopy and particulate filtration efficiency (PFE) tests revealed that there was no structural or functional deterioration observed in the face masks even after they underwent excessive exposure to ozone (five 1-minute exposures). Interestingly, for face masks exposed to ozone gas for 5 min, the amplification of HCoV-229E RNA by reverse transcription polymerase chain reaction suggested a loss of infectivity under the effect of ozone, primarily owing to the damage caused to viral envelopes or envelope proteins. Ozone gas is a strong oxidizing agent with the ability to kill viruses on hard-to-reach surfaces, including the fabric structure of face masks. These results suggest that it may be possible to rapidly disinfect contaminated face masks using a plasma generator in a well-ventilated place.
