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Cell Studies on SARS-CoV-2 B.1.1.7 Introductions, Microbiome HGT, Heterogeneity Within Tumors

Researchers from Yale University, the US Centers for Disease Control and Prevention, and elsewhere retrace SARS-CoV-2 B.1.1.7 introductions and spread within the US for a Cell pre-print article. Using sequence data for 770 B.1.1.7 isolates identified in the US between mid-December and mid-February, along with more than 1,900 SARS-CoV-2 sequences from the UK and elsewhere, the team found evidence of SARS-CoV-2 B.1.1.7 introductions into New York, California, and Florida, along with transmission and spread within the US. "Despite travel restrictions and increased testing requirements, we found evidence for a large number of independent B.1.1.7 introductions into the US, many of which have led to secondary community transmission," the authors note, adding that "our data highlight the relative ease with which SARS-CoV-2 variants can spread undetected throughout the US, particularly in areas where genomic surveillance efforts are minimal."

An international team tracks horizontal gene transfer (HGT) in human gut microbial communities, identifying an apparent boost in gene swapping by gut bugs in places with more industrialized food production and lifestyles. For their analyses, researchers considered nearly 7,800 sequenced gut microbes from a Broad Institute microbiome library and from the Global Microbiome Conservancy collection, which includes samples from more than a dozen global populations. Along with HGT events within individual gut microbiomes, they noted that HGT appeared to be more pronounced in individuals from places with increasing industrialization and urbanization. "Comparison across human populations reveals that industrialized lifestyles are associated with higher HGT rates and that the functions of HGTs are related to the level of host industrialization," they report. "Our results suggest that gut bacteria continuously acquire new functionality based on host lifestyle and that high rates of HGT may be a recent development in human history linked to industrialization."

Members of the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium and PCAWG Evolution and Heterogeneity Working Group present findings from an intra-tumor heterogeneity-focused analysis of almost 2,700 tumor samples representing more than three dozen human cancer types. By analyzing whole-genome sequence data for 2,658 tumors, the researchers saw signs of sub-clonal expansion in more than 95 percent of the samples considered, including sub-clones that varied by cancer type and positive selection for those carrying related cancer drivers. "Our results underline the importance of [intra-tumor heterogeneity] and its drivers in tumor evolution and provide a pan-cancer resource of comprehensively annotate sub-clonal events from whole-genome sequencing," the authors write.

The Scan

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