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Biology subjects

Savelkoul, P. H. M.

Publications and source records attributed to Savelkoul, P. H. M..

2 recordsLinked to original sources

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

Higher prevalence of Bacteroides fragilis in Crohn's disease exacerbations and strain-dependent increase of epithelial resistance

Bacteroides fragilis has previously been linked to Crohns disease (CD) exacerbations, but results are inconsistent and underlying mechanisms unknown. This study investigates the epidemiology of B. fragilis and its virulence factors bft (enterotoxin) and ubiquitin among 181 CD patients and the impact on the intestinal epithelial barrier in vitro. The prevalence of B. fragilis was significantly higher in active (n=69/88, 78.4%) as compared to remissive (n=58/93, 62.4%, p=0.018) CD patients. Moreover, B. fragilis was associated with intestinal strictures. Interestingly, the intestinal barrier function, as examined by transepithelial electrical resistance (TEER) measurements of Caco-2 monolayers, improved when exposed to secretomes of bft-positive (increased TEER [~]160%, p<0.001) but not when exposed to bft- negative strains. Whole metagenome sequencing and metabolomics, respectively, identified 19 coding sequences and two metabolites that discriminated TEER-increasing from non-TEER-increasing strains. This study revealed a higher B. fragilis prevalence during exacerbation. Surprisingly, bft-positive secretomes improved epithelial resistance.

microbiology