Mechanism Of Antiviral Activity Induced By Lygodium Japonicum Against Infectious Bronchitis Virus In H1299 Cells

Infectious bronchitis virus(IBV)belongs to the genus Gammacoronavirus within th e family Coronaviridae and is an enveloped virus with a positive-sense single-stranded RNA genome.IBV causes infectious bronchitis in chickens caused by is a poultry coron avirus that causes infectious bronchitis(IB)and has given rise to serious economic losse s to the poultry industry worldwide.Due to the lack of effective chemicals,live vaccines have been widely utilized to control IB.However,the great diversity of IBV strains and the successive appearance of novel IBV strains make it difficult to prevent IB in chicke ns using vaccines.Consequently,it is very important to explore economical,safe and eff ective control methods.In fact,many medicinal plants and herbal formulas can effective ly prevent animal and human virus diseases,but their anti-viral mechanisms are poorly understood.In this experiment,the anti-IBV activity of ten plants was tested and three plants with strong antiviral activity were screened.The molecular mechanism of anti-IBV in the extract of L.japonicum was revealed by modern molecular biology techniques.The research results lay the foundation for further elucidating the antiviral mechanism of L.japonicum,and provide a theoretical basis for the development and utilization of medicinal plants to effectively prevent and control viral diseases.The experimental results are summarized as follows:1.Detection of anti-IBV activities of the extracte from 10 plants indicated that extracts from Paeonia suffruticosa Andr,Senecio scandens Buch,Solanum nigrum Linn,Gleditsia sinensis Lam,Lygodium japonicum(Thunb.)Sw.were able to inhibit the proliferation of IBV in different degree.Among them,the effects of L.japonicum,C.monnieri and G.sinensis were more significant.2.RT-PCR and Western blotting analyses showed that the syntheses of viral RNA and N protein in the IBV-infected H1299 cells treated with the methanol extract of L.japonicum decreased significantly,suggesting that the methano extract of L.japonicum can stimulate H1299 to produce the anti-IBV activity.3.Quantitative RT-PCR and Western blotting were used to analyze the regulation effect of extracts from L.japonicum on cytokines.The results showed that the expression of interferon ? in the IBV-infected H1299 cells treated with the methanol extract of L.japonicum increased significantly while the expression of cytokine IL-6 and IL-8 had no obvious change,suggesting that the methanol extract of L.japonicum may upregulate the interferon ? expression to inhibit IBV replication.