Attenuation of influenza virus infectivity with herbal-marine compound (HESA-A): an in vitro study in MDCK cells

Abstract

Background: The influenza virus is still one of the most important respiratory risks affecting humans which require effective treatments. In this case, traditional medications are of interest. HESA-A is an active natural biological compound from herbal-marine origin. Previous studies have reported that the therapeutic properties of HESA-A are able to treat psoriasis vulgaris and cancers. However, no antiviral properties have been reported.

Methods: This study was designed to investigate the potential antiviral properties of HESA-A and its effects in modulating TNF-α and IL-6 cytokine levels. HESA-A was prepared in normal saline as a stock solution (0.8 mg/ml, pH = 7.4). Percentages of cell survival when exposed to different concentrations of HESA-A at different time intervals was determined by MTT assay. To study the potential antiviral activity of HESA-A, Madin-Darby Canine Kidney (MDCK) cells were treated with the effective concentration (EC50) of HESA-A (0.025 mg/ml) and 100 TCID50/0.1 ml of virus sample under different types of exposure.

Results: Based on the MTT method and hemagglutination assay (HA), HESA-A is capable of improving cell viability to 31% and decreasing HA titre to almost 99% in co-penetration exposures. In addition, based on quantitative real-time PCR (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA), it was found that HESA-A causes decrements in TNF-α and IL-6 cytokine expressions, which was significant for TNF-α (p ≤ 0.05) but not for IL-6.

Conclusion: In conclusion, HESA-A was effective against influenza infection through suppressing cytokine expression.

Figure 1

MTT optical densities for cell viability in response to different types of exposure of HESA-A and virus (averages of 4 independent tests) (mean ± SD). *: Significantly different from values obtained for the co-penetration treatment compared to the virus untreated sample (p < 0.05).

Figure 2

Comparison of the percent of protection of HESA-A and Amantadine on cell viability. Data analyzed by SPSS, one way ANOVA are averages of 4 independent experiments (mean ± SD). HESA-A showed a higher degree of protection towards cell viability in comparison with Amantadine treatments. It was significantly higher in co- and pre-penetration treatments. *: Significantly different from values obtained for co- & pre-penetration treatments compared to Amantadine treatments (p < 0.05).