Bootstrap values with sellekchem 100/100 are indicated at the nodes of the … These trees derived from different genomic regions were consistent for most of the 2006-2007 GII/4 strains investigated. However, the sequences in cluster III exhibited discordant branching orders among ORFs (Fig. (Fig.22 and and3).3). Cluster III was placed within the GII/4 genotype in the ORF2 and ORF3 trees (Fig. (Fig.2A2A and and3B).3B). However, it was placed outside the GII/4 clusters and grouped with the GII sequences; these are referred to as GII/10 and GII/12 in the ORF1 tree (Fig. (Fig.3A,3A, bootstrap value 100/100). These data suggest genetic exchanges around the border between ORF1 and ORF2 during the evolutionary histories of the cluster III strains.

Potential ancestors for the putative recombination events were not identifiable with currently available genome sequences in the public database. Cluster I 2006b had the longest branch length among all trees examined (Fig. (Fig.22 and and3),3), a finding consistent with its most recent detection. Amino acid signatures of the 2006-2007 GII/4 epidemic strains. The amino acid substitutions specific to the cluster I 2006b strains were examined. The deduced amino acid sequences of ORF1, ORF2, and ORF3 of the 33 cluster I 2006b obtained in the present study were aligned with those of the past ~15 years of epidemic strains described in Fig. Fig.22 and and3.3. Amino acids specific to clusters I and II were extracted and referred to as amino acid signatures of the 2006b and 2006a epidemic variants, respectively.

Twenty-six amino acid signatures were identified for the cluster I 2006b strains (Fig. (Fig.4A).4A). The numbers of the signatures were 6, 1, 2, 1, 1, 3, 7, and 5 in the N-term, NTPase, 3A, VPg, 3Cpro, 3Dpol, VP1 (capsid), and VP2 protein regions, respectively. All seven signatures of the capsid protein were mapped in the protruding P2 domain. Siebenga et al. (46) referred to 48 amino acid positions in the capsid protein as informative sites when at least two epidemic strains had an identical amino acid. Of the 48 positions 7 were perfectly preserved only in the 2006b strains in Japan. The cluster II 2006a strains each had a distinct signature pattern (Fig. (Fig.4B).4B). The numbers of 2006a signatures were Anacetrapib 5, 4, 1, 6, 3, and 2 in the N-term, NTPase, 3A, 3Dpol, VP1, and VP2 protein regions, respectively. VPg and 3Cpro of 2006a had no signatures. FIG. 4. Unique amino acid substitutions of the 2006-2007 GII/4 epidemic strains. The deduced amino acids of NoV GII/4 ORF1s, ORF2s, and ORF3s of the 2006b and 2006a strains were aligned with those of the past chronological epidemic strains. Amino acids are each … Amino acid variation among GII/4 strains.