Isoelectric point determination of norovirus virus-like particles by capillary isoelectric focusing with whole column imaging detection.

A capillary isoelectric focusing-whole column imaging detection (CIEF-WCID) method was used to determine the isoelectric point (pI) of norovirus virus-like particles (VLPs). The VLPs were produced from noroviruses that represented the two genogroups, genogroup I (Funabashi, Seto, and Norwalk) and genogroup II (Hawaii, Kashiwa, and Narita). Using the imaged CIEF-WCID detection technique, separation was accomplished using a short (4-5 cm) internally coated capillary (100-microm diameter) and a whole-column optical absorption imaging detector operated at 280 nm. CIEF-WCID experiments showed the similarity of the pI values of VLPs from genogroups I and II, with pI values of 5.9, 5.9, 6.0, and 6.0 for Funabashi, Norwalk, Seto, and Hawaii. The two other VLPs displayed pI values of 5.5 (Kashiwa) and 6.9 (Narita). The VLP peaks were shown to be reproducibility resolved. CIEF-WCID shows great promise for norovirus detection in public health, clinical, and food safety applications, as CIEF-WCID overcomes several limitations of the currently used genetic and immunological methods.