Using genomic surveillance, a team led by scientists from the University of California, San Francisco, have determined that the COVID-19 outbreak in Northern California was due to the introduction of multiple SARS-CoV-2 strains. The researchers used a recently developed method called MSSPE — short for metagenomic sequencing with spiked primer enrichment — to rapidly enrich and assemble viral genomes directly from samples from 36 infected individuals across nine California counties and the Grand Princess cruise ship. As reported in Science, phylogenetic analyses showed the introduction of at least seven different SARS-CoV-2 strains into California, including epidemic strains associated with Washington State, and point to limited transmission between communities. The findings, the study's authors write, support contact tracing, social distancing, and travel restrictions to contain further spread of the virus. GenomeWeb has more on this study, here.
A Johns Hopkins University team has developed a rapid and highly precise approach for CRISPR genome editing based on light activation. Called very fast CRISPR, or vfCRISPR, the method involves altering the system's guide RNA sequence with light-sensitive nucleotide, which allows the Cas9 enzyme to bind to its target DNA but not cleave it until activated by light. Describing their work in Science, the investigators say vfCRISPR creates double-strand breaks at the submicrometer and second scales, and is precise enough to allow one allele of a gene to be edited at a time, enabling DNA-repair studies at high resolution in space, time, and genomic coordinates. GenomeWeb also has more on this, here.