Structural stability of SARS-CoV-2 degrades with temperature

SARS-CoV-2 is a novel coronavirus which has caused the COVID-19 pandemic. Other known coronaviruses show a strong pattern of seasonality, with the infection cases in humans being more prominent in winter. Although several plausible origins of such seasonal variability have been proposed, its mechanism is unclear. SARS-CoV-2 is transmitted via airborne droplets ejected from the upper respiratory tract of the infected individuals. It has been reported that SARS-CoV-2 can remain infectious for hours on surfaces. As such, the stability of viral particles both in liquid droplets as well as dried on surfaces is essential for infectivity. Here we have used atomic force microscopy to examine the structural stability of individual SARS-CoV-2 virus like particles at different temperatures. We demonstrate that even a mild temperature increase, commensurate with what is common for summer warming, leads to dramatic disruption of viral structural stability, especially when the heat is applied in the dry state. This is consistent with other existing non-mechanistic studies of viral infectivity, provides a single particle perspective on viral seasonality, and strengthens the case for a resurgence of COVID-19 in winter. Statement of Scientific SignificanceThe economic and public health impact of the COVID-19 pandemic are very significant. However scientific information needed to underpin policy decisions are limited partly due to novelty of the SARS-CoV-2 pathogen. There is therefore an urgent need for mechanistic studies of both COVID-19 disease and the SARS-CoV-2 virus. We show that individual virus particles suffer structural destabilization at relatively mild but elevated temperatures. Our nanoscale results are consistent with recent observations at larger scales. Our work strengthens the case for COVID-19 resurgence in winter.

Application of CRISPR/Cas9 genome editing technology in the research of eye diseases / 中华实验眼科杂志

The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) is an adaptive immune system against invasive viruses and exogenous DNA,which is developed by bacteria and archaer during long-term evolution.With advances in technology,researchers have found that CRISPR/ Cas9 system can precisely edit the genomes of eukaryotic cells through insertion,replacement or deletion of target genes.Using CRISPR/Cas9 genome editing technology,researchers found that overexpression of paired box gene 6 (PAX6) in cornea can cause congenital corneal epithelial damage;this technology promoted the research on the pathogenic mechanism of keratin 12 (KRT12) mutation in Meesmann corneal epithelial dystrophy;it has also built congenital cataract animal models by knocking out the G JA8 gene and αA lens gene,which is beneficial to the application of the diagnosis and pathological analysis of congenital cataract.In addition,the researchers have used CRISPR/Cas9 genome editing technology to confirm the correlation of RHOS334 mutated RHO allele,P23H mutated RHO gene,Y347X mutated Pde6b gene,and mutant RP9 allele with retinitis pigmentosa.The application of this technology has provided evidence to support the association of KCNJ13 gene and mutant CEP290 gene with Leber congenital amaurosis.CRISPR/Cas9 can provide target spot of intraocular neovascular diseases the targeted therapy by editing of VEGFR2 gene and TXNIP gene,and it also playse an important role in the study of pathogenic genes and establishment of animal models for proliferative vitreoretinopathy and retinoblastoma.In this review,we introduced the evolutionary history,the molecular characteristics and the mechanism of CRISPR/Cas9,and summarized its current research advances in eye diseases.

The progress of nanomedicine inspired by bacteriophage / 药学学报

Nanomedicine offers great promise for early diagnosis and treatment of formidable diseases. The unique morphology and biology characteristics of bacteriophage provide unprecedented opportunity for such endeavor. The paper summarizes the application of bacteriophage in nanobiomaterials, nanomedicine, nanomedicine delivery and nanodiagnosis, especially the nano-imaging reagents and future direction concerning nanomedicine based on bacteriophage.