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ViruSurf, available at http://gmql.eu/virusurf/, is a large public database of viral sequences and integrated and curated metadata from heterogeneous sources (GenBank, COG-UK and NMDC); it also exposes computed nucleotide and amino acid variants, called from original sequences. A GISAID-specific ViruSurf database, available at http://gmql.eu/virusurf_gisaid/, offers a subset of these functionalities. Given the current pandemic outbreak, SARS-CoV-2 data are collected from the four sources; but ViruSurf contains other virus species harmful to humans, including SARS-CoV, MERS-CoV, Ebola, and Dengue.The database is centered on sequences, described from their biological, technological, and organizational dimensions. In addition, the analytical dimension characterizes the sequence in terms of its annotations and variants. The web interface enables expressing complex search queries in a simple way; arbitrary search queries can freely combine conditions on attributes from the four dimensions, extracting the resulting sequences.Several example queries on the database confirm and possibly improve results from recent research papers; results can be recomputed over time and upon selected populations. Effective search over large and curated sequence data may enable faster responses to future threats that could arise from new viruses.

Since the outbreak of the COVID-19 pandemic, many research organizations have studied the genome of the SARS-CoV-2 virus; a body of public resources have been published for monitoring its evolution. While we experience an unprecedented richness of information in this domain, we also ascertained the presence of several information quality issues. We hereby propose CoV2K, an abstract model for explaining SARS-CoV-2-related concepts and interactions, focusing on viral mutations, their co-occurrence within variants, and their effects. CoV2K provides a clear and concise route map for understanding different connected types of information related to the virus; it thus drives a process of data and knowledge integration that aggregates information from several current resources, harmonizing their content and overcoming incompleteness and inconsistency issues. CoV2K is available for exploration as a graph that can be queried through a RESTful API addressing single entities or paths through their relationships. Practical use cases demonstrate its application to current knowledge inquiries.

Motivation The ongoing evolution of SARS-CoV-2 and the rapid emergence of variants of concern at distinct geographic locations have relevant implications for the implementation of strategies for controlling the COVID-19 pandemic. Combining the growing body of data and the evidence on potential functional implications of SARS-CoV-2 mutations can suggest highly effective methods for the prioritization of novel variants of potential concern, e.g. increasing in frequency locally and/or globally. However, these analyses may be complex, requiring the integration of different data and resources. We claim the need for a streamlined access to up-to-date and high-quality genome sequencing data from different geographic regions/countries, and the current lack of a robust and consistent framework for the evaluation/comparison of the results. Results To overcome these limitations, we developed ViruClust, a novel tool for the comparison of SARS-CoV-2 genomic sequences and lineages in space and time. ViruClust is made available through a powerful and intuitive web-based user interface. Sophisticated large-scale analyses can be executed with a few clicks, even by users without any computational background. To demonstrate potential applications of our method, we applied ViruClust to conduct a thorough study of the evolution of the most prevalent lineage of the Delta SARS-CoV-2 variant, and derived relevant observations. By allowing the seamless integration of different types of functional annotations and the direct comparison of viral genomes and genetic variants in space and time, ViruClust represents a highly valuable resource for monitoring the evolution of SARS-CoV-2, facilitating the identification of variants and/or mutations of potential concern. Availability and implementation ViruClust is openly available at http://gmql.eu/viruclust/. Supplementary information Supplementary data are available at Bioinformatics online.