Forsythoside a inhibits the avian infectious bronchitis virus in cell culture

Abstract

Forsythoside A is a polyphenolic constituent of the fruits of Forsythia suspensa Vahl. which is widely used as an antiinflammatory agent in traditional Chinese medicine. In the present study, the effects of forsythoside A on cell infection by avian infectious bronchitis virus were assessed. A real-time fluorescence quantitative PCR assay was used to determine mRNA content of IBV N gene. The pretreatment of cells with forsythoside A, adding forsythoside A post infection of cells, and treatment of virus with forsythoside A were analysed. The inhibitory effect of forsythoside A was confirmed by infecting primary chicken embryo kidney cells. Infected cells were inhibited by forsythoside A treatment. The data indicated that forsythoside A has the potential to prevent IBV infection in vitro. Copyright © 2010 John Wiley & Sons, Ltd.

Figure 1

The cytopathic effects in CEK cells infected with progeny IBV from cells treated with the concentrations of forsythoside A (0.64 mm, 0.32 mm, 0.16 mm and 0) indicated to the left. (a) Pretreatment of CEK cells with forsythoside A. (b) The effect of forsythoside A on infected CEK cells; (c) Treatment of virus with forsythoside A. This figure is available in colour online at http://wileyonlinelibrary.com/journal/ptr

Figure 2

The effect of forsythoside A pretreatment on CEK cells. (A) PCR product shown by agarose gel electrophoresis. Real‐time PCR product of IBV N gene in cells pretreated with forsythoside A is shown. (B) Contents of IBV N gene measured by real‐time PCR in cells pretreated with forsythoside A. It shows the mRNA contents of IBV N gene in the mock infection sample, IBV control and forsythoside A groups (0.16 mm, 0.32 mm, 0.64 mm, CT values were normalized by β‐actin). Error line represents the standard deviation (SD) (n = 3). Asterisk indicates the comparative results of mRNA levels (signified by RQ unit) between 0.64 mm sample and IBV control sample (***p < 0.001, SPSS.16.0 used).

Figure 3

Histogram showing the content of IBV treated with forsythoside A directly. (A) Direct effect of forsythoside A on virions detected by real‐time PCR, the PCR product of IBV N gene is shown by agarose gel electrophoresis. (B) mRNA levels of IBV N gene measured by real‐time PCR on direct effect of forsythoside A on virions. It shows the mRNA contents of IBV N gene in the mock infection group, IBV control and forsythoside A groups (0.16 mm, 0.32 mm, 0.64 mm). Error line represents the standard deviation (SD) (n = 3). Asterisk indicates the comparative results of mRNA levels (signified by RQ unit) between each concentration of forsythoside A group and IBV control (***p < 0.001).