Erik Hjerde

Erik Hjerde

*This is an algorithmically generated author record based on publicly available information.

Current Organizations / Institutes

The organizations/institutes from the scholar's latest article


Erik Hjerde has a total of 124 co-authors. Here are the top co-authors by number of shared publications:

  • Nils Peder Willassen

    Norwegian Structural Biology Center and Department of Chemistry, Faculty of Science and Technology, UiT The Arctic University of Norway, Tromsø, Norway

    10 shared publications
  • Miriam Khider

    Norwegian Structural Biology Centre, Department of Chemistry, Faculty of Science and Technology, UiT-The Arctic University of Norway, N-9037 Tromsø, Norway

    4 shared publications
  • Hilde Hansen

    Norwegian Structural Biology Centre, Department of Chemistry, Faculty of Science and Technology, UiT-The Arctic University of Norway, Tromsø, Norway

    3 shared publications
  • Jostein A. Johansen

    Norwegian Structural Biology Centre, Department of Chemistry, Faculty of Science and Technology, UiT-The Arctic University of Norway, Tromsø, Norway

    3 shared publications
  • Nils Peder Willassen

    Norwegian Structural Biology Centre, Department of Chemistry, Faculty of Science and Technology, UiT-The Arctic University of Norway, Tromsø, Norway

    3 shared publications
  • Peik Haugen

    UiT Norges arktiske universitet

    3 shared publications

Latest Publications

  • Open Access

    Community needs for FAIR pathogen data: a cross-sectional survey of infectious-disease researchers and educators

    by Geert van Geest, Daniel Thomas-Lopez, Anna A. Feitzinger, Lily A. Weissgold, Sam Halabi, Isabel Cuesta, Erik Hjerde, Kim Tamara Gurwitz, Nishtha Arora, Aitana Neves, et al.

    Background: Datasets related to infectious diseases are essential for public health decision-making, yet their reuse remains limited by persistent barriers to data sharing and integration. Achieving data that are Findable, Accessible, Interoperable, and Reusable (FAIR) is widely recognized as essential for accelerating scientific discovery and enabling coordinated responses to emerging threats, but the needs of the global pathogen data community have not been systematically characterized. Aim: This study, conducted by the Pathogen Data Network (PDN), aims to identify infrastructural and educational priorities among stakeholders working with infectious disease-related data—namely researchers, educators, healthcare professionals, bioinformaticians, and policymakers who generate, curate, or use pathogen data, in order to guide community-responsive support for data sharing and interoperability. Methods: A cross-sectional stakeholder survey was disseminated as an open, non-probability (convenience) survey to prospective participants reached through PDN networks, targeted mailing lists, and open professional and social-media channels. A total of 136 responses from researchers, healthcare professionals, bioinformaticians, and educators were analyzed descriptively to identify prioritized barriers, training needs, and preferred support mechanisms. Results: Respondents consistently identified structural constraints as the primary impediments to effective data use, including limited funding (74%), data-aggregation challenges (68%), and a shortage of skilled personnel (52%). Respondents identified bioinformatics for infectious disease research (68%) as the highest priority for training, followed by guidance on using the integrated pathogen data and tools portal provided by the PDN, the Pathogens Portal (51%). The Pathogens Portal was also ranked as the most essential PDN resource (72%). Preferred training formats included virtual short courses (68%) and webinars (66%). Notably, while researchers emphasized technical subjects like machine learning, educators prioritized foundational case studies. Conclusion: These findings provide an evidence-based descriptive summary of community needs and suggest that barriers to FAIR pathogen data are predominantly systemic rather than purely technological. The survey framework and openly available dataset offer a reusable template for assessing needs in other communities and regions. By aligning training, infrastructure development, and outreach with empirically identified priorities, organizations supporting infectious disease research can strengthen the interoperability and reuse of data and establish a benchmark for future community-driven improvements.

  • Open Access

    Exploring the Frozen Armory: Antiphage Defense Systems in Cold-Adapted Bacteria with a Focus on CRISPR-Cas Systems

    by Greta Daae Sandsdalen, Animesh Kumar, Erik Hjerde

    Our understanding of the antiphage defense system arsenal in bacteria is rapidly expanding, but little is known about its occurrence in cold-adapted bacteria. In this study, we aim to shed light on the prevalence and distribution of antiphage defense systems in cold-adapted bacteria, with a focus on CRISPR-Cas systems. Using bioinformatics tools, Prokaryotic Antiviral Defense LOCator (PADLOC) and CRISPRCasTyper, we mapped the presence and diversity of antiphage defense systems in 938 available genomes of cold-adapted bacteria from diverse habitats. We confirmed that CRISPR-Cas systems are less frequent in cold-adapted bacteria, compared to mesophilic and thermophilic species. In contrast, several antiphage defense systems, such as dXTPases and DRTs, appear to be more frequently compared to temperate bacteria. Additionally, our study provides Cas endonuclease candidates with a potential for further development into cold-active CRISPR-Cas genome editing tools. These candidates could have broad applications in research on cold-adapted organisms. Our study provides a first-time map of antiphage defense systems in cold-adapted bacteria and a detailed overview of CRISPR-Cas diversity.


  • Open Access

    Comparative analysis of HiSeq3000 and BGISEQ-500 sequencing platform over whole genome sequencing metagenomics data

    by Animesh Kumar, Espen M. Robertsen, Nils P. Willassen, Juan Fu, Erik Hjerde

    Recent advances in sequencing technologies and platforms have enabled to generate metagenomics sequences using different sequencing platforms. In this study, we analyzed and compared shotgun metagenomic sequences generated by HiSeq3000 and BGISEQ-500 platforms from 12 sediment samples collected across the Norwegian coast. Metagenomics DNA sequences were normalized to an equal number of bases for both platforms and further evaluated by using different taxonomic classifiers, reference databases, and assemblers. Normalized BGISEQ-500 sequences retained more reads and base counts after preprocessing, while a slightly higher fraction of HiSeq3000 sequences were taxonomically classified. Kaiju classified a higher percentage of reads relative to Kraken2 for both platforms, and comparison of reference database for taxonomic classification showed that MAR database outperformed RefSeq. Assembly using MEGAHIT produced longer assemblies and higher total contigs count in majority of HiSeq3000 samples than using metaSPAdes, but the assembly statistics notably improved with unprocessed or normalized reads. Our results indicate that both platforms perform comparably in terms of the percentage of taxonomically classified reads and assembled contig statistics for metagenomics samples. This study provides valuable insights for researchers in selecting an appropriate sequencing platform and bioinformatics pipeline for their metagenomics studies.


  • Open Access

    A survey into the contribution of regional/national pathogen data platforms and on the resources needed to develop and maintain them

    by Aitana Neves, Nils P Willassen, Erik Hjerde, Isabel Cuesta, Corinne S Martin, Heleri Inno, Diana Pilvar, Kim Ng, David Salgado, Jacques van Helden, et al.

    Background Regional/national SARS-CoV-2 genomic data platforms (DP) have played a key role during the Covid-19 pandemic to centralize data, curate, process and re-share them in a consistent form and pseudonymized/anonymized to international repositories. In Europe, several countries were able to establish such infrastructures rapidly and put them in production over the course of 2021, some earlier. Methods This survey aimed to estimate the effort that was needed to establish and run these DPs during the sequencing peak of the pandemic in 2021, including activities from data curation to data brokering, and what it would take to expand these DPs to other pathogens and antimicrobial resistance from 2023 onwards. Results Overall, a median of 10 person-months (PM) were used by each DP over 2021 and a median of 18 PM (per year) would be needed to expand activities from 2023 onwards. This survey shows that short-term funding remains commonplace and a struggle for the majority of DPs. Key supporters and arguments (e.g. centered around efficiency and cost-savings) for public health authorities and research funding bodies have also been identified to help individual data platforms in strengthening their funding proposals. Conclusions Ultimately, we propose that DPs get connected into a supra-national entity to build a stronger case and get access to major infrastructure funding grants at the European and global levels.


  • Open Access

    FAIR+E pathogen data for surveillance and research: lessons from COVID-19

    by Aitana Neves, Isabel Cuesta, Erik Hjerde, Terje Klemetsen, David Salgado, Jacques van Helden, Nadim Rahman, Nazeefa Fatima, Nestoras Karathanasis, Pawel Zmora, et al.

    The COVID-19 pandemic has exemplified the importance of interoperable and equitable data sharing for global surveillance and to support research. While many challenges could be overcome, at least in some countries, many hurdles within the organizational, scientific, technical and cultural realms still remain to be tackled to be prepared for future threats. We propose to (i) continue supporting global efforts that have proven to be efficient and trustworthy toward addressing challenges in pathogen molecular data sharing; (ii) establish a distributed network of Pathogen Data Platforms to (a) ensure high quality data, metadata standardization and data analysis, (b) perform data brokering on behalf of data providers both for research and surveillance, (c) foster capacity building and continuous improvements, also for pandemic preparedness; (iii) establish an International One Health Pathogens Portal, connecting pathogen data isolated from various sources (human, animal, food, environment), in a truly One Health approach and following FAIR principles. To address these challenging endeavors, we have started an ELIXIR Focus Group where we invite all interested experts to join in a concerted, expert-driven effort toward sustaining and ensuring high-quality data for global surveillance and research.


  • Open Access

    Detection of Klebsiella pneumoniae human gut carriage: a comparison of culture, qPCR, and whole metagenomic sequencing methods

    by Kenneth Lindstedt, Dorota Buczek, Torunn Pedersen, Erik Hjerde, Niclas Raffelsberger, Yutaka Suzuki, Sylvain Brisse, Kathryn Holt, Ørjan Samuelsen, Arnfinn Sundsfjord

    Klebsiella pneumoniae is an important opportunistic healthcare-associated pathogen and major contributor to the global spread of antimicrobial resistance. Gastrointestinal colonization with K. pneumoniae is a major predisposing risk factor for infection and forms an important hub for the dispersal of resistance. Current culture-based detection methods are time consuming, give limited intra-sample abundance and strain diversity information, and have uncertain sensitivity. Here we investigated the presence and abundance of K. pneumoniae at the species and strain level within fecal samples from 103 community-based adults by qPCR and whole metagenomic sequencing (WMS) compared to culture-based detection. qPCR demonstrated the highest sensitivity, detecting K. pneumoniae in 61.2% and 75.8% of direct-fecal and culture-enriched sweep samples, respectively, including 52/52 culture-positive samples. WMS displayed lower sensitivity, detecting K. pneumoniae in 71.2% of culture-positive fecal samples at a 0.01% abundance cutoff, and was inclined to false positives in proportion to the relative abundance of other Enterobacterales present. qPCR accurately quantified K. pneumoniae to 16 genome copies/reaction while WMS could estimate relative abundance to at least 0.01%. Quantification by both methods correlated strongly with each other (Spearman’s rho = 0.91). WMS also supported accurate intra-sample K. pneumoniae sequence type (ST)-level diversity detection from fecal microbiomes to 0.1% relative abundance, agreeing with the culture-based detected ST in 16/19 samples. Our results show that qPCR and WMS are sensitive and reliable tools for detection, quantification, and strain analysis of K. pneumoniae from fecal samples with potential to support infection control and enhance insights in K. pneumoniae gastrointestinal ecology. What is the context? What is new? What is the impact? qPCR and WMS are valid methods for the detection and characterization of colonizing K. pneumoniae with potential to enhance our understanding of the gastrointestinal ecology of this important pathogen.


  • Open Access

    Prevalence, diversity and transferability of the Tn 916 -Tn 1545 family ICE in oral streptococci

    by Tracy Munthali Lunde, Erik Hjerde, Mohammed Al-Haroni

    Background: The Tn916-Tn1545 family of Integrative Conjugative Elements (ICE) are mobile genetic elements (MGEs) that play a role in the spread of antibiotic resistance genes. The Tn916 harbors the tetracycline resistance gene tet(M) and it has been reported in various bacterial species. The increase in the levels of tetracycline resistance among oral streptococci is of great concern primarily due to the abundance of these species in the oral cavity and their ability to act as reservoirs for antibiotic resistance genes.Methods: In the current study, we screened 100 Norwegian clinical oral streptococcal isolates for the presence and diversity of the Tn916-Tn1545 family. In addition, we investigated the transferability the elements, and the associated transfer frequencies.Results: We observed that 21 isolates harboured the Tn916-Tn1545 family and that two of these elements were the novel Tn6815 and Tn6816. The most prevalent member of the Tn916 -Tn1545 family observed in the Norwegian clinical oral streptococcal isolates was the wild type Tn916.Conclusion: The detection of other members of this family of ICE and varying transfer frequencies suggests high versatility of the Tn916 element in oral streptococci in Norway.


  • Open Access

    Effects of fecal microbiota transplantation in subjects with irritable bowel syndrome are mirrored by changes in gut microbiome

    by Rasmus Goll, Peter Holger Johnsen, Erik Hjerde, Joseph Diab, Per Christian Valle, Frank Hilpusch, Jorunn Pauline Cavanagh

    Irritable bowel syndrome (IBS) is a common disorder of the lower gastrointestinal tract. The pathophysiology is far from settled, but a gut microbial dysbiosis is hypothesized to be a contributing factor. We earlier published a randomized double-blind placebo-controlled clinical trial on fecal microbiota transplantation (FMT) for IBS – the REFIT trial. The present data set describes the engraftment and includes participants from the study who received active FMT; 14 participants with effect of FMT (Effect) and 8 without (No effect). Samples were collected at baseline, after 6 and 12 months. Samples from the transplants (Donor) served as a comparator. In total 66 recipient samples and 17 donor samples were subjected to deep metagenomic sequencing, and taxonomic and functional analyses were performed. Alpha diversity measures showed a significantly increased diversity and evenness in the IBS groups compared to the donors. Taxonomic profiles showed higher relative abundance of phylum Firmicutes, and lower relative abundance of phylum Bacteroidetes, compared to donors at baseline. This profile was shifted toward the donor profile following FMT. Imputed growth rates showed that the resulting growth pattern was a conglomerate of donor and recipient activity. Thirty-four functional subclasses showed distinct differences between baseline samples and donors, most of which were shifted toward a donor-like profile after FMT. All of these changes were less pronounced in the No effect group. We conclude that FMT induces long-term changes in gut microbiota, and these changes mirror the clinical effect of the treatment. The study was registered in ClinicalTrials.gov (NCT02154867).


  • Open Access

    DNA ligases of Prochlorococcus marinus : an evolutionary exception to the rules of replication

    by Erik Hjerde, Ashleigh Maguren, Elizabeth Rzoska-Smith, Bronwyn Kirby, Adele Williamson

    DNA ligases, essential enzymes which re-join the backbone of DNA come in two structurally-distinct isoforms, NAD-dependent and ATP-dependent, which differ in cofactor usage. The present view is that all bacteria exclusively use NAD-dependent DNA ligases for DNA replication, while archaea and eukaryotes use ATP-dependent DNA ligases. Some bacteria also possess auxiliary ATP-dependent DNA ligases; however, these are only employed for specialist DNA repair processes. Here we show that in the genomes of high-light strains of the marine cyanobacterium Prochlorococcocus marinus , an ATP-dependent DNA ligase has replaced the NAD-dependent form, overturning the present paradigm of a clear evolutionary split in ligase usage. Genes encoding partial NAD-dependent DNA ligases are found on mobile regions in highlight genomes and lack domains required for catalytic function. This constitutes the first reported example of a bacterium that relies on an ATP-dependent DNA ligase for DNA replication and recommends P. marinus as a model to investigate the evolutionary origins of these essential DNA-processing enzymes.


  • Open Access

    Metadata og dokumentasjon innen livsvitenskap

    by Erik Hjerde

    Presentasjon frå RDA-kurs i FAIR forskingsdatakuratering 2020