Relatedness of calicivirus homologues of NV p22. Calicivirus homologues of NV p22 were compared by phylogeny (A) or CLUSTALW amino acid alignment (B). CNV07 is Cuernavaca 2007 [GenBank:GU937002], HOV is Houston virus [GenBank:EU310927], U201 is Saitama U201 virus [GenBank:AB039782], NV is Norwalk virus [GenBank:NC_001959], MNV-CR6 and –CW3 are murine norovirus strains CR6 [sequence is identical to [GenBank:EU004676] except for one amino acid change (D50G) (personal communication, “Skip” Virgin)] and CW3 [GenBank:EF014462], respectively, and FCV is feline calicivirus strain Urbana [GenBank:L40021]. Underlined amino acids indicate predicted membrane association domains as predicted by PSIPRED (available online at http://www.psipred.net/psiform.html). Bolded amino acids indicate the MERES motif. (C) Amino acids 65–71 of NV p22 were aligned with norovirus p22L that lack full MERES motif conservation. TCH97 is Texas Children’s Hospital 1997 [GenBank:GU930737]; U3 [GenBank:AB039776], U4 [GenBank:AB039777], U16 [GenBank:AB039778], U17 [GenBank:AB039779], U25 [GenBank:AB039780], Neustrelitz260 [GenBank:AY772730] and Leverkusen267 [GenBank:EU424333]. In B and C, * indicates conserved residues, : indicates strong group conservation, and . indicates weak group conservation.