Genetic classification of "Norwalk-like viruses"

Reverse transcription-polymerase chain reaction has been used worldwide for the diagnosis of Norwalk-like virus (NLV) infection, yet a commonly accept ed genetic classification scheme has not been established. Amino acid seque nces from four regions of open-reading frame 2 (ORF2) were used to analyze 101 NLV strains, including 2 bovine strains, On the basis of this analysis, a genetic classification scheme is proposed that differentiates 99 human s trains into 2 major genetic groups consisting of 5 and 10 genetic clusters, respectively. The 2 bovine strains constitute a newly defined third major genetic group composed of 2 putative clusters represented by each strain. T his classification scheme is well supported by the analysis of the entire O RF2 sequences from 38 strains selected to represent the genetic diversity o f the human strains used above. This scheme should provide a firm scientifi c basis for the unified classification of NLV strains detected around the w orld.