Cranberry and Grape Juice Drinks Affect Infectivity, Integrity, and Pathology of Enteric Viruses in an Animal Model

摘要

The health benefits of potable fruit juices prepared from species of grape (e.g., Vitis labrusca) and cranberry (Vaccinium macrocarpori) have been the focus of numerous anecdotal and prospective studies. Few investigators have addressed the antiviral activity of juices from these or related species on enteric (intestinal) viruses within the family Reoviridae. Simian rotavirus SA-11 and bovine reovirus type 3 were used in these studies as representative enteric viral agents. Infectivity titers/viral detection were determined by isolation/immunofluoresence, transmission electron microscopy (TEM), polyacrylamide gel electrophoresis (PAGE) of viral dsRNA, and the reverse transcription polymerase chain reaction (rtPCR). Pretreatment of monolayers of monkey kidney epithelial-like (MA-104) cells in culture with either store-purchased or manufacturer-supplied (no added sugar) cranberry (CJ) and grape juice (GJ) at concentrations ≥ 16% of control reduced infectivity titers of rota- and reovirus by more than one order of magnitude. Vitamin C at concentrations present in store-purchased juice drinks had no effect on viral titers. Reovirus dsRNA was not detected by PAGE in monolayers pretreated with either juice and in cell-free suspensions of virus, suggesting an adverse effect by both juices on adsorption/penetration and a direct inactivation of viral particles per se. TEM did not detect virus penetration or egress among monolayers pretreated with store-purchased or manufacturer-supplied CJ. Detection of rotavirus RNA (i.e., amplicon yield) by rtPCR was markedly reduced after pretreatment of monolayers with manufacturer-supplied CJ and GJ drinks. Loss of cell viability/cytotoxicity of the host cells as a result of exposure to the juices was not observed by trypan blue exclusion, cell passage, or quantitative adenylate kinase release. Antiviral activity by CJ and GJ drinks in vitro, was supported by testing in the mouse model.