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We compared the results of high-hydrostatic-pressure (HHP) inactivation of murine norovirus type 1 (MNV-1) and Tulane virus (TV) obtained by a porcine gastric mucin binding assay followed by quantitative reverse transcription-PCR (referred to here as the PGM-MB/PCR assay) and a plaque assay and evaluated HHP inactivation of a human norovirus (HuNoV) genogroup I genotype 1 (GI.1) strain and a HuNoV GII.4 strain by using the PGM-MB/PCR assay. Viruses were treated at different pressure levels for 2 min at 4 or 21°C in culture medium of neutral pH and in culture medium of pH 4 at 21°C. The log reductions of infectious MNV-1 and TV particles caused by HHP were assessed using the PGM-MB/PCR and plaque assays, while the log reductions of HuNoVs were assessed by the PGM-MB/PCR assay only. For TV and MNV-1, the two pressure inactivation curves obtained using the plaque and PGM-MB/PCR assays were almost identical at <2-log-reduction levels regardless of the treatment temperature and pH. Further increasing the pressure over the 2-log-reduction level resulted in higher log reductions of TV and MNV-1, as assessed by the plaque assay, but did not increase the log reductions, as assessed by the PGM-MB/PCR assay. HHP treatments could achieve maximum reductions of ϳ3 and 3.5 log units for GI.1 and GII.4, respectively, as assessed by the PGM-MB/PCR assay. On the basis of these results, it can reasonably be concluded that the PGM-MB/PCR assay would very likely be able to estimate HHP inactivation of HuNoV at <2-log-reduction levels. It would also likely conservatively quantify HHP inactivation of the GI.1 strain at 2-to 3-log-reduction levels and the GII.4 strain at 2-to 3.5-log-reduction levels.H uman norovirus (HuNoV) is the leading cause of foodborne illnesses in the United States (1). It has frequently been associated with a variety of ready-to-eat foods, including berries, salsa, and guacamole, and raw shellfish, such as oysters (2-4). Currently, the lack of suitable cell culture systems and practical small-animal models has been hindering research for developing and/or identifying effective processing methods to inactivate HuNoV (1, 5). Therefore, evaluation of the efficacy of processing treatments must rely on HuNoV surrogates. The accuracy of methods that use these surrogates is questionable since direct comparison of methods that use surrogates with methods that use HuNoV is not possible. Molecular biology methods, mostly quantitative reverse transcription-PCR (qRT-PCR), can be used for HuNoV quantification. However, these methods can detect only the presence of HuNoV RNA and cannot distinguish between infectious and noninfectious virus particles.HuNoVs are reported to bind to histo-blood group antigens (HBGAs) in the human intestinal tract, and HBGAs are considered the attachment factors necessary for infection (6, 7). To initiate infection, HuNoVs need to be able to bind to HBGAs to enter the host cells. Porcine gastric mucin (PGM) contains HBGAs and has been shown to be able to bind to genogroup I (GI) and genogroup II...

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The effects of agarose gel strips without and with 0.03 m(r) electroendosmosis (EEO) on isoelectric focusing (IEF) were studied. It is shown that only agarose without EEO can be used for IEF. The effects of electrode buffer strips using agarose with different EEO of 0, 0.03, 0.08, 0.20 m(r) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and native PAGE were also studied. It apparently did not affect SDS-PAGE, but affected native PAGE to a certain extent. The higher the EEO value was, the more water was present on the agarose gel strip during a separation. Agarose gel strips with an EEO of 0.2 m(r) are not suitable as electrode buffer strips for native PAGE.