Unifying classical and molecular taxonomic classification:: analysis of the Podoviridae using BLASTP-based tools

We defined phage genera by measuring genome relationships by the numbers of shared homologous/orthologous proteins. We used BLAST-based tools (CoreExtractor.vbs and CoreGenes) to analyze 55 fully sequenced bacteriophage genomes from the NCBI and EBI databases. This approach was first applied to the T7-related phages. Using a cut-off score of 40% homologous proteins, we identified three genera within the T7-related phages, redefined the (phi 29-related phages, and introduced five novel genera. The T7- and (phi 29-related phages were given subfamily status and named Autographivirinae and Picovirinae, respectively. Our results confirm and refine the ICTV phage classification, enable elimination of errors in public databases, and provide a straightforward tool for the molecular classification of new phage genomes. Crown Copyright (C) 2008 Published by Elsevier Masson SAS. All rights reserved.