van Alphen, L. B. | Search bioRxiv

bioRxiv2021

A novel B.1.1.523 SARS-CoV-2 variant that combines many spike mutations linked to immune evasion with current variants of concern

In the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic several variants have emerged that are linked to increased transmissibility and immune evasion. These variants are recognized as variants of concern (VOC). In this study, we describe a B.1.1.523 variant that shares many spike mutations with current VOC. Receptor-binding domain mutations E484K and S494P were observed but also a deletion (position 156-158) in the N-terminal antigenic supersite that is similar to the delta-variant. These mutations are linked to immune evasion in VOC that could lead to less effective vaccines. This variant has been reported in various different countries and continents despite the dominance of B.1.1.7 (alpha) and B.1.617.2 (delta) variant. Furthermore, the B.1.1.523 pangolin lineage as a whole is recognized as a variant under monitoring since 14th of July 2021.

microbiology↗

bioRxiv2020

Harmonization of whole genome sequencing for outbreak surveillance of Enterobacteriaceae and Enterococci

Whole genome sequencing (WGS), is becoming the facto standard for bacterial typing and outbreak surveillance of resistant bacterial pathogens. We performed a three-center ring trial to assert if inter-laboratory harmonization of WGS is achievable, for this goal. To this end, a set of 30 bacterial isolates comprising of various species belonging to the Enterobacteriaceae and Enterococcus genera were selected and sequenced using the same protocol on the Illumina MiSeq platform in each individual centre. All generated sequencing data was analysed by 1 centre using BioNumerics (6.7.3) for i) genotyping origin of replications & antimicrobial resistance genes, ii) core-genome (cgMLST) for E. coli and K. pneumoniae & whole-genome multi locus sequencing typing (wgMLST) for all species. Additionally, a split k-mer analysis was performed to determine the number of SNPs between samples. A precision of 99.0% and an accuracy of 99.2% was achieved for genotyping. Based on cgMLST, only in 2/27 and 3/15 comparisons a discrepant allele was called between two genomes, for E. coli and K. pneumonia, respectively. Based on wgMLST, the number of discrepant alleles ranged from 0 to 7 (average 1.6). For SNPs, this ranged from 0-11 SNPs (average 3.4). Furthermore, we demonstrate that using different de novo assemblers to analyse the same dataset introduces up to 150 SNPs, which surpasses most thresholds for bacterial outbreaks. This shows the importance of harmonisation of data processing surveillance of bacterial outbreaks. Summarizing, multi-center WGS for bacterial surveillance is achievable, but only if protocols are harmonized.

microbiology↗