Phylogenetic trees of A) a 206-nt region of the RNA-dependent polymerase gene of 1 human genogroup (G) IV strain (Hu/GIV.1/FortLauderdale/1998/US), 2 recently published canine noroviruses (GIV.2/170/2004/IT, Bari/91/2007/IT) (5,13), and the novel canine Viseu strain reported in the study (boldface); and B) full-length amino acid sequence of viral protein (VP) 1 of norovirus strains of GI–GV detected in animals and human strains Hu/GI.1/Norwalk/1968/US, Hu/GI.3/DesertShield/1993/US, and Hu/GII.4/Bristol/1993/UK. The Viseu strain (boldface) forms tentatively a novel genogroup (GVI) with strains Ca/Bari/91/2007/IT and Hu/Chiba/2004/JP. Phylogenetic analysis was performed by using TreeCon software with Jukes and Cantor correction with bootstrap analysis (n = 1,000), and the tree topology was inferred by using neighbor-joining. Ca, canine; Hu, human; Po, porcine; Bo, bovine; Ov, ovine; Mu, murine.