Molecular characterization of noroviruses detected in diarrheic stools of Michigan and Wisconsin dairy calves: circulation of two distinct subgroups

Abstract

Noroviruses have emerged as the leading worldwide cause of acute non-bacterial gastroenteritis in humans. The presence of noroviruses in diarrheic stool samples from calves on Michigan and Wisconsin dairy farms was investigated by RT-PCR. Norovirus-positive samples were found on all eight farms studied in Michigan and on 2 out of 14 farms in Wisconsin. Phylogenetic analyses of partial polymerase and capsid sequences, derived for a subset of these bovine noroviruses, showed that these strains formed a group which is genetically distinct from the human noroviruses, but more closely related to genogroup I than to genogroup II human noroviruses. Examination of 2 full and 10 additional partial capsid (ORF2) sequences of these bovine strains revealed the presence of two genetic subgroups or clusters of bovine noroviruses circulating on Michigan and Wisconsin farms. One subgroup is "Jena-like", the other "Newbury agent-2-like".

Fig. 1

Phylogenetic analysis based on deduced amino acid sequences of a 172-nucleotide region of the RNA polymerase gene of bovine norovirus strains from Michigan,11MSU-MW, 3470DD, A-1SVD, B-1SVD, 3503DD and 2086MR (this study); from Wisconsin, 803484WI and 803466WI (this study); from Germany, Jena (AJ011099); from the UK, Bo/Penrith55/00/UK (AY126476), Bo/Dumfries/94/UK (AY126474), and Newbury agent-2 (AF097917); of bovine caliciviruses from Ohio, CV500-OH (AY151258) and CV514-OH (AY151259); and of human norovirus strains Desert Shield (U04469), Norwalk (M87661), Southampton (L07418), MX (U22498) and Lordsdale (X86557). Human sapovirus strain, Hu/SLV/Lyon/598/97/F (AJ271056), was included as the outgroup sequence. GenBank accession numbers are in parentheses. Bootstrap values at nodes are given if >50%.

Fig. 2

Alignment of the deduced amino acid sequences of the entire capsid gene (ORF2) of bovine norovirus strains: Michigan strains, B-1SVD and 11MSU-MW (this study); Jena (AJ011099) and Newbury (Newbury agent-2, AF097917). Full name of strain and/or GenBank accession numbers are in parentheses.

Fig. 3

Alignment of deduced amino acid sequences corresponding to a 744-nucleotide central variable region of the capsid gene of bovine norovirus strains from Michigan and Wisconsin, A-1SVD, B-1SVD, 3505DD, 2167MR, 2086MR, 11MSU-MW, 1GM, 21MSU-MW, 17–19MSU-MW, 2387108MI, 803484WI, 32MSU-MW (this study); from Germany, Jena (AJ011099); from the UK, Newbury (Newbury agent-2, AF097917), Dumfries (Bo/Dumfries/94/UK, AY126474), Penrith (Bo/Penrith55/00/UK, AY126476), and Aberystwyth (Bo/Aberystwyth24/00/UK, AY126475); and from the Netherlands, CH126 (Bo/NLV/CH126/1998/NL, AF320625) and CH131 (Bo/NLV/CH131/1998/NL, AF320113). Full name of strain and/or GenBank accession numbers are in parentheses.

Fig. 4

Phylogenetic analysis based on deduced amino acid sequences corresponding to a 744-nucleotide central variable region of the capsid gene of bovine noroviruses 11MSU-MW, 1GM, 21MSU-MW, 17–19MSU-MW, 2387108MI, 803484WI, 32MSU-MW, B-1SVD, A-1SVD, 3505DD, 2167MR, and 2086MR (this study); Jena (AJ011099); Bo/Penrith55/00/UK (AY126476); Bo/Aberystwyth24/00/UK (AY126475); Bo/Dumfries/94/UK (AY126474); Newbury agent-2 (AF097917); Bo/NLV/CH131/1998/NL (AF320113); Bo/NLV/CH126/1998/NL (AF320625); and of human noroviruses Desert Shield (U04469), Southampton (L07418), Norwalk (M87661), MX (U22498) and Lordsdale (X86557). Human sapovirus strain, SLV/Mex14917/2000 (AF435813), was included as the outgroup sequence. GenBank accession numbers are in parentheses. Bootstrap values at nodes are given if >60%.