Monomeric catechin and dimeric procyanidin B2 against human norovirus surrogates and their physicochemical interactions.
Plant polyphenols have shown antiviral activity against several human pathogens, but their physicochemical interactions are not well-understood. The objectives of this study were to compare the antiviral activity between monomeric catechin and dimeric procyanidin B2 (PB2) using cultivable human norovirus surrogates (feline calicivirus (FCV-F9) and murine norovirus (MNV-1)) and to understand their potential antiviral mechanism using virus-like particles (VLPs) and the P domain of human norovirus GII (HNoV GII.4). Surrogate viruses at 5 log PFU/mL were treated with 0.5-5 mg/mL monomeric catechin monohydrate, PB2 or phosphate buffered saline (PBS, pH 7.2; control) at 37 °C over 24 h. Infectivity was determined using plaque assays and data from triplicate experiments were statistically analyzed. PB2 at 0.5 mg/mL and 1 mg/mL reduced FCV-F9 to undetectable levels after 3 h and MNV-1 by 0.21 and 1.23 log PFU after 24 h, respectively. Monomeric catechins at 1 mg/mL reduced FCV-F9 to undetectable levels after 6 h and MNV-1 titers to undetectable levels after 24 h. In addition, PB2 was shown to directly bind the P domain, the main capsid structure of HNoVs in the ratio of 1:1 through spontaneous interactions. Electrostatic interactions played a dominant role between PB2 and the P domain. PB2 significantly altered tertiary but not secondary structures of VLPs. Transmission electron microscopy demonstrated that PB2 aggregated VLPs, further indicating interactions between them. These findings indicate that PB2 causes structural changes of the P domain of VLPs, mainly through direct interaction leading to HNoV inactivation.
['Liu|Dan|D|', 'Deng|Jianjun|J|', 'Joshi|Snehal|S|', 'Liu|Pengbo|P|', 'Zhang|Chao|C|', 'Yu|Yan|Y|', 'Zhang|Ruijuan|R|', 'Fan|Daidi|D|', 'Yang|Haixia|H|', "D'Souza|Doris H|DH|"]
D000818:Animals D000998:Antiviral Agents D044946:Biflavonoids D017927:Calicivirus, Feline D002392:Catechin D002415:Cats D005517:Foodborne Diseases D006801:Humans D029322:Norovirus D044945:Proanthocyanidins D010948:Viral Plaque Assay D053585:Virus Attachment D038301:Virus Inactivation
Procyanidin B2 Norovirus Interaction P domain