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    Cranberry and Grape Juices Affect Tight Junction Function and Structural Integrity of Rotavirus-Infected Monkey Kidney Epithelial Cell Monolayers
    (SPRINGER, 2011) Lipson, Steven M.; Gordon, Robert E.; Ozen, Fatma S.; Karthikeyan, Laina; Kirov, Nicolas; Stotzky, Guenther
    Cranberry juice (CJ) and grape juice (GJ) from Vaccinium macrocarpon and Vitis labrusca, respectively, and purified proanthocyanidins (PACs) from these species are recognized to possess antiviral activity. The effects of CJ and GJ on tight junction (TJ) structure and function among rotavirus-infected monkey kidney epithelial cells (MA-104) in monolayer cultures were evaluated. Antiviral activity by cranberry PACs of rotavirus in cell-free suspension was investigated by a rotavirus antigen [i.e., viral capsid protein 6 (VP6)] capture enzyme-linked immunosorbent assay (ELISA) and by transmission electron microscopy (TEM). MA-104 monolayers were treated with CJ, GJ, or cranberry juice cocktail (CJC) drink before inoculation with rotavirus. TJ function and structural integrity were measured by changes in transepithelial electrical resistance (TEER) and by reduction of signal intensity of the TJ alpha-claudin 1 by immunofluorescence. The inhibitory activity of CJ and GJ on viral RNA synthesis, as a function of viral concentration, was determined by reverse transcription polymerase chain reaction (rtPCR). After 4 days, virus-infected monolayers pretreated with GJ (Concord and Niagara GJs) had TEER readings similar to uninfected controls. CJ and CJC also had a significant protective effect (P < 0.05) on TJ function, but to a lesser extent than GJ. Disorganization of TJ integrity commenced at 24- to 36-h post-viral inoculation, but this effect was reduced by pretreatment with CJ or GP of monolayer cultures. TEM showed aggregation of rotavirus by cranberry PACs. The destruction of rotavirus capsid proteins VP6, in cell-free suspension was inversely related to the concentration of cranberry PACs (C-PAC). Loss of rotavirus RNA by CJ or GJ was inversely related to viral infectivity titers. CJ, GJ, or PAC-associated antiviral activity has been linked to modifications in cellular physiologic events and to physical factors (e.g., PAC-mediated viral aggregation) that probably compromise viral infectivity. Multiple cell physiological and physical events must be considered when determining the mechanisms associated with the antiviral (i.e., rotavirus) activity of CJ, GJ, and PACs.
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    Effect of pH on Anti-Rotavirus Activity by Comestible Juices and Proanthocyanidins in a Cell-Free Assay System
    (SPRINGER, 2012) Lipson, Steven M.; Ozen, Fatma S.; Karthikeyan, Laina; Gordon, Ronald E.
    Cranberry (Vaccinium macrocarpon) and grape (Vitis labrusca) juices, and these species' secondary plant metabolites [i.e., proanthocyanidins (PACs)] possess antiviral activity. An understanding of the mechanism(s) responsible for these juices and their polyphenolic constituents' direct effect on enteric virus integrity, however, remains poorly defined. Using the rotavirus (RTV) as a model enteric virus system, the direct effect of manufacturer-supplied and commercially purchased juices [Ocean Spray Pure Cranberry 100 % Unsweetened Juice (CJ), Welch's 100 % Grape Juice (GJ), 100 % Concord (PG) and 100 % Niagara juices (NG)] and these species' cranberry (C-PACs) and grape PACs (G-PACs) was investigated. Loss of viral capsid integrity in cell-free suspension by juices and their PACs, and as a factor of pH, was identified by an antigen (RTV) capture enzyme-linked immunosorbent assay. At native and an artificially increased suspension at or near pH 7, loss of viral infectivity occurred after 5 min, in the order CJ > NG = GJ > PG, and PG > GJ = NG = CJ, respectively. Antiviral activity of CJ was inversely related to pH. Grape, but not cranberry PACs, displayed a comparatively greater anti-RTV activity at a suspension pH of 6.7. Anti-RTV activity of C-PACs was regained upon reduction of RTV-cranberry PAC suspensions to pH 4. An alteration or modification of Type A PAC (of V. macrocarpon) structural integrity at or near physiologic pH is suggested to have impacted on this molecule's antivirus activity. Type B PACs (of V. labrusca) were refractive to alternations of pH. Significantly, findings from pure system RTV-PAC testing paralleled and in turn, supported those RTV-juice antiviral studies. Electron microscopy showed an enshroudment by PACs of RTV particles, suggesting a blockage of viral antigenic binding determinants. The implications of our work are significant, especially in the interpretation of PAC (and PAC-containing food)-RTV interactions in the differing [pH] conditions of the gastrointestinal tract.