Impact of Theaflavins-Enriched Tea Leaf Extract TY-1 against Surrogate Viruses of Human Norovirus: In Vitro Virucidal Study

Figures

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  Figure 1. Virucidal effects of TY-1 on FCV and MNV. (A–D) The FCV (A,C) or MNV (B,D) solution was mixed with Dex (final dosage: 2.5 mg/mL (A,B) or 12.5 mg/mL (C,D)) or TY-1 (0.3–5.0 mg/mL (A,B) or 25.0 mg/mL (C,D)). Then, the mixtures were incubated at 25 °C from 10 s to 24 h. The data are expressed as mean ± SD (n ≥ 6 per group). The Student’s t–test was used to analyze the statistically significant differences between the Dex group and TY-1 group with each dosage; * p < 0.05; ** p < 0.01; *** p < 0.001; NT: not tested.

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  Figure 2. Virucidal effects of catechins, TFs, TFs+catechins, and TY-1 on FCV and MNV. (A,B) The FCV (A) or MNV (B) solution was mixed with Dex (final dosage: 2.5 mg/mL), and catechins (0.034 mg/mL), TFs (0.082 mg/mL), TFs+catechins (0.116 mg/mL), or TY-1 (5.0 mg/mL). Then, the mixtures were incubated at 25 °C for 3 and 24 h. The data are expressed as mean ± SD (n ≥ 6 per group). Student’s t-test with Bonferroni correction for multiple comparison was used to analyze the statistically significant differences between the different groups; * p < 0.05; ** p < 0.01; *** p < 0.001; ns: not significant.

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  Figure 3. Virucidal effects of TY-1 on FCV and MNV on a dry surface. (A,B) Dex (final dosage: 2.5 mg/mL) or TY-1 (5.0 mg/mL) was applied on FCV (A) or MNV (B) on a dry surface, and the samples were placed at 25 °C for 10 min. The data are expressed as mean ± SD (n ≥ 3 per group). Student’s t-test was used to analyze the statistically significant differences between the Dex and TY-1 groups; ** p < 0.01; *** p < 0.001.

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  Figure 4. Effect of TY-1 on an MNV structural protein. A solution with purified MNV was mixed with Dex (final dosage: 2.5 mg/mL) or TY-1 (5.0 mg/mL) and incubated at 25 °C for 0 or 24 h. Then, Western blotting was performed to detect the MNV VP1 protein. The results were representative of two individual experiments.

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  Figure 5. Effect of TY-1 on FCV and MNV genomes. (A,B) A solution with purified FCV (A) or MNV (B) was mixed with Dex (final dosage: 2.5 mg/mL) or TY-1 (5.0 mg/mL) and incubated at 25 °C for 0 or 24 h. Then, the extracted viral RNA from the treated viruses was analyzed using RT-PCR. RT-PCR was performed using the FCV-primer set to amplify a 264 bp region on the gene encoding FCV VP1 (A) or the MNV-primer set to amplify a 549 bp region on the gene encoding the MNV nonstructural polyprotein (B). The results were representative of more than two individual experiments.

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  Figure 6. Morphology of Dex- or TY-1-treated FCV and MNV virions. (A–D) A solution with purified FCV or MNV was mixed with Dex (final dosage: 2.5 mg/mL) (A,C) or TY-1 (5.0 mg/mL) (B,D) and incubated at 25 °C for 6 h. Then, the virions were observed using TEM. The results were descriptive images of Dex- and TY-1-treated viral particles.