Biology subjects

Wieler, L. H.

Publications and source records attributed to Wieler, L. H..

3 recordsLinked to original sources

bioRxiv2022

Genome-wide association reveals host-specific genomic traits in Escherichia coli

Escherichia coli is an opportunistic pathogen that can colonize or infect various host species. There is a significant gap in our understanding to what extent genetic lineages of E. coli are adapted or restricted to specific hosts. In addition, genomic determinants underlying such host specificity are unknown.By analyzing a randomly sampled collection of 1198 whole-genome sequenced E. coli isolates from four countries (Germany, UK, Spain, and Vietnam), obtained from five host species (human, pig, cattle, chicken, and wild boar) over 16 years, from both healthy and diseased hosts, we demonstrate that certain lineages of E. coli are frequently detected in specific hosts. We report a novel nan gene cluster, designated nan-9, putatively encoding acetylesterases and determinants of uptake and metabolism of sialic acid, to be associated with the human host as identified through genome wide association studies. In silico characterization predicts nan-9 to be involved in sialic acid (Sia) metabolism. In vitro growth experiments with a representative {Delta}nan E. coli mutant strain, using sialic acids 5-N-acetyl neuraminic acid (Neu5Ac) and N-glycolyl neuraminic acid (Neu5Gc) as the sole carbon source, indicate an impaired growth behaviour compared to the wild-type. In addition, we identified several additional E. coli genes that are potentially associated with adaptation to human, cattle and chicken hosts, but not for the pig host. Collectively, this study provides an extensive overview of genetic determinants which may mediate host specificity in E. coli. Our findings should inform risk analysis and epidemiological monitoring of (antimicrobial resistant) E. coli.

genomics↗

bioRxiv2021

Establishment of a publicly available core genome multilocus sequence typing scheme for Clostridium perfringens

Clostridium perfringens is a spore-forming anaerobic pathogen responsible for a variety of histotoxic and intestinal infections in humans and animals. High-resolution genotyping aiming to identify bacteria at strain level has become increasingly important in modern microbiology to understand pathogen transmission pathways and to tackle infection sources. This study aimed at establishing a publicly available genome-wide multilocus sequence-typing scheme for C. perfringens. 1,431 highly conserved core genes (1.34 megabases; 50% of the reference genome genes) were indexed for a core-genome-based MLST scheme for C. perfringens. As an example, we applied the scheme to 87 poultry and 73 non-poultry strains (total=160). The genotyping results of the 160 genomes were congruent in terms of resolution and tree topology between allele-based and single-nucleotide-polymorphism-based core-genome typing. For the analysis of poultry strains of C. perfringens concerning the country of isolation, NetB-toxin gene carriage and clinical disease, we used 60 allelic differences as a clustering threshold. The results showed that poultry strains from a single country formed a cluster (n=17 clusters including 46 strains). Two clusters included six strains from four different countries. These strains were netB-positive, as were seven strains from Denmark and two strains from Finland, possibly indicating common sources of netB-positive strains. In terms of clinical presentation, different clusters of strains were associated with cases of suspected necrotic enteritis. Strains from sick birds grouped with strains from healthy birds or meat samples showing that potentially virulent strains are widespread and that host-related factors contribute significantly to NE. In summary, a publicly available scheme and an allele nomenclature database for genomic typing of C. perfringens has been established and can be used for broad-based and standardised epidemiological studies.

microbiology↗

bioRxiv2021

Genome-wide insights into population structure and host specificity of Campylobacter jejuni

The zoonotic pathogen Campylobacter jejuni is among the leading causes of foodborne diseases worldwide. While C. jejuni colonises many wild animals and livestock, persistence mechanisms enabling the bacterium to adapt to host species guts are not fully understood. In order to identify putative determinants influencing host preferences of distinct lineages, bootstrapping based on stratified random sampling combined with a k-mer-based genome-wide association was conducted on 490 genomes from diverse origins in Germany and Canada. We show a strong association of both the core and the accessory genome characteristics with distinct host animal species, indicating multiple adaptive trajectories defining the evolution of C. jejuni lifestyle preferences in different ecosystems. Here, we demonstrate that adaptation towards a specific host niche ecology is most likely a long evolutionary and multifactorial process, expressed by gene absence or presence and allele variations of core genes. Several host-specific allelic variants from different phylogenetic backgrounds, including dnaE, rpoB, ftsX or pycB play important roles for genome maintenance and metabolic pathways. Thus, variants of genes important for C. jejuni to cope with specific ecological niches or hosts may be useful markers for both surveillance and future pathogen intervention strategies.

genomics↗