# PHI-base

The Pathogen-Host Interactions database (PHI-base) is a biological database that contains manually curated information on genes experimentally proven to affect the outcome of pathogen-host interactions. The database has been maintained by researchers at Rothamsted Research and external collaborators since 2005. PHI-base has been part of the UK node of ELIXIR, the European life-science infrastructure for biological information, since 2016.

## Background

The Pathogen-Host Interactions database was developed to utilise the growing number of verified genes that mediate an organism's ability to cause disease and/or trigger host responses.
The web-accessible database catalogues experimentally verified pathogenicity, virulence, and effector genes from bacterial, fungal, and oomycete pathogens which infect animal, plant, and fungal hosts. PHI-base was the first online resource devoted to the identification and presentation of information on fungal and oomycete pathogenicity genes and their host interactions. PHI-base is a resource for the discovery of candidate targets in medically and agronomically important fungal and oomycete pathogens for intervention with synthetic chemistries and natural products (fungicides).
Each entry in PHI-base is curated by domain experts and supported by strong experimental evidence (gene disruption experiments) as well as literature references in which the experiments are described. Each gene in PHI-base is presented with its nucleotide and deduced amino acid sequence as well as a detailed structured description of the predicted protein's function during the host infection process. To facilitate data interoperability, genes are annotated using controlled vocabularies (Gene Ontology terms, EC Numbers, etc.), and links to other external data sources such as UniProt, EMBL, and the NCBI taxonomy services.

## Current developments

Version 4.17 (May 2024) of PHI-base provides information on 9973 genes from 296 pathogens and 249 hosts and their impact on 22415 interactions as well on efficacy information on ~20 drugs and the target sequences in the pathogen. PHI-base currently focuses on plant pathogenic and human pathogenic organisms including fungi, oomycetes, and bacteria. The entire contents of the database can be downloaded in a tab delimited format. Since the launch of version 4, the PHI-base is also searchable using the PHIB-BLAST search tool, which uses the BLAST algorithm to compare a user's sequence against the sequences available from PHI-base. The database providers recently announced the launch of PHI-base 5, a new gene-centric version of PHI-base, through a press release on the Rothamsted Research website. A summary of the improvements made is also available.
In 2016 the plant portion of PHI-base was used to establish a Semantic PHI-base search tool.
PHI-base has been aligned with Ensembl Genomes since 2011, FungiDB since 2016, and Global Biotic Interactions (GloBI) since 2018. All new PHI-base releases are integrated by these independent databases.
PHI-base is a resource for many applications including:
› The discovery of conserved genes in medically and agronomically important pathogens, which may be potential targets for chemical intervention
› Comparative genome analyses
› Annotation of newly sequenced pathogen genomes
› Functional interpretation of RNA sequencing and microarray experiments
› The rapid cross-checking of phenotypic differences between pathogenic species when writing articles for peer review
PHI-base use has been cited in over 900 peer-reviewed articles.
Since 2015, the website has linked to an online literature curation tool called PHI-Canto, enabling community-driven literature curation for various pathogenic species. PHI-Canto employs a community curation framework that not only offers a curation tool but also includes a phenotype ontology and controlled vocabularies using unified languages and rules used in biology experiments. The central concept of this framework is the introduction of a 'Metagenotype', which allows the annotation and assignment of phenotypes to specific pathogen mutant-host interactions. PHI-Canto extends the single species curation tool developed for PomBase (https://www.pombase.org), the model organism database for fission yeast.

## Funding

PHI-base is a National Capability funded by the Biotechnology and Biological Sciences Research Council (BBSRC), a UK research council.