Magic™ Anti-Norovirus VP1 Monoclonal antibody, Clone N230640

This study examined whether a specific (six-nucleotide) sequence in the norovirus polymerase (POL) gene could act as a marker of GII.4 epidemics in Australia in 2001-2005. The predominant variant (pv) in an epidemic year (2002, 2004) changed relative to the pv in the previous year (AACTTG in 2001 to AATCTG in 2002, AATCTG in 2003 to AACTTG in 2004). The pv in a non-epidemic year (2003, 2005) was the same as in the preceding year (AATCTG in 2002 and 2003, AACTTG in 2004 and 2005). Thus, specific short nucleotide sequences could act as markers of major GII.4 norovirus epidemics.

The inability to grow human noroviruses in cell culture has greatly impeded the studies of their pathogenesis and immunity. Vesiviruses, in the family Caliciviridae, grow efficiently in cell culture and encode a unique protein in the subgenomic region designated as leader of the capsid protein (LC). We hypothesized that LC might be associated with the efficient replication of vesiviruses in cell culture and promote the replication of human norovirus in cells. To test this hypothesis, a recombinant plasmid was engineered in which the LC region of feline calicivirus (FCV) was placed under the control of the cytomegalovirus promoter (pCI-LC) so that the LC protein could be provided in trans to replicating calicivirus genomes bearing a reporter gene. We constructed pNV-GFP, a recombinant plasmid containing a full-length NV genome with a green fluorescent protein (GFP) in the place of VP1. The transfection of pNV-GFP in MVA-T7-infected cells produced few GFP-positive cells detected by fluorescence microscopy and flow cytometry analysis. When pNV-GFP was cotransfected with pCI-LC in MVA-T7-infected cells, we observed an increase in the number of GFP-positive cells (ca. 3% of the whole-cell population). Using this cotransfection method with mutagenesis study, we identified potential cis-acting elements at the start of subgenomic RNA and the 3' end of NV genome for the virus replication. We conclude that LC may be a viral factor which promotes the replication of NV in cells, which could provide a clue to growing the fastidious human noroviruses in cell culture.