Neighbour-joining tree of 215 bp amplificates of the ORF1/2 junction of norovirus. P1 to P5 are sequences from stool specimens of patients and CE1 and CE2 from canteen employees. Prototype sequences in bold and italics are from GenBank: II.4 Lordsdale, X86557; II.4 2004 DenHaag54, EF126962; II.4 2006a Terneuzen70, EF126964; II.4 2006b Nijmegen115, EF126966. Bootstrap values > 60% are indicated. The scale represents nucleotide substitutions per site.