The support for Helicobacter in the MD 257 library was particularly compelling because there were 12 unique transcripttags and one rRNA-tag to this genus. We evaluated the phylogenetic relatedness of the mule deer Helicobacter with other Helicobacter based on four of the protein-coding transcripts and on the single 16S rRNA sequence. All analyses demonstrated that the Helicobacter detected in the mule deer lymph node is a unique organism that affiliates with the H. pylori cluster ( Fig. 3A and 3B, and Fig. S2 ). Because 16S rRNA sequence data is available for more species, we were able to further demonstrate that the closest Figure 1 . MEGAN comparison of the taxonomic profiles of (A) cDNA transcript-tags from 454 sequencing five individual lymph node samples and two lymph node sample pools and (B) genomic DNA-tags from four individual lymph node samples. Depicted are assignments with bit score cutoffs $50. Circle sizes are scaled logarithmically. Not assigned: sequencing-tags matching to sequences in the NCBI database that are not assigned to taxa; no hits: sequencing-tags not matching to any sequences in the NCBI database. doi:10.1371/journal.pone.0013432.g001 Figure 2 . MEGAN comparison of taxonomic profiles of MD 257 cDNA transcript-tags analyzed against the protein database (red) and the ribosomal database (blue), and of V6 amplicon 16S rRNA-tags analyzed against the ribosomal database (green). Bit score cutoff for the protein database comparison was set at 50, and confidence cutoffs for the ribosomal database comparisons were set at 80%. doi:10.1371/journal.pone.0013432.g002 relative to mule deer Helicobacter is a newly described H. cetorum isolated from different dolphin species (Lagenorhynchus acutus, Lagenorhynchus obliquidens, and Tursiops truncatus) and a beluga whale (Delphinapterus leucas) [36] (Fig. 3A) .