Study of anti-viral and immunomodulatory effects of polysaccharide extracts from seaweeds on the viral infections

• Main Authors: Ya-Huang Chiu, 邱雅凰
• Other Authors: Chang-Jer Wu
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/58448973572063544910

博士 === 國立臺灣海洋大學 === 食品科學系 === 100 === The seaweed polysaccharide extracts of ulvan, carrageenan, (Chlorella pyrenoidosa extracts, CPE). The total sugars, sulfate contents and molecular weights with no direct correlations. The diverse activities may depend on given structures in the sulfated polysaccharides. In this study, we identified that the polysaccharide extracts from Ulva can inhibit JEV infection in Vero cells. Mechanistic studies further revealed that the Ulva polysaccharide extracts can block virus adsorption and thus make the virus unable to enter cells. The Ulva polysaccharide extracts also effectively decrease the production of proinflammatory cytokines in the JEV-infected primary mixed glia cells. In animal study, the JEV-infected C3H/HeN mice appeared neurobehavioral abnormalities at the 5th day and died at the 7th day post-infection. However, the JEV infected mice pretreated with the Ulva polysaccharide extracts can delay the onset of hind limb paralysis and thereby prevent the mice from death. In this study, we reported carrageenan also has a strong and effective anti-EV 71 activity able to reduce plaque formation, prevent viral replication before or during viral adsorption, as well as inhibit EV 71-induced apoptosis. In virus binding assay, carrageenan was shown able to bind EV 71 firmly, forming carrageenan-viruses complexes, whereby the virus-receptor interaction is likely disrupted. In this study, the antiviral activity of hot water extracts from microalgae (Chlorella pyrenoidosa extracts, CPE) and carrageenan on dengue virus type II (DV2) was evaluated. In vitro antiviral studies, the CPE and carrageenan could interference the early step of dengue virus infection. And CPE and carrageenan direct react with DV2 virus particles was better than other treatments. In the DV2 infected C3H/HeN mice model, all of eighth-day-old mice would die within 6 - 8 days after intracranial inoculation of DV2 with 100 PFU/mouse, some of them developed the typical dengue syndrome such as plasma leakage and gastrointestinal hemorrhagic. In vivo antiviral studies, eighth-day-old mice inoculate with mixture of DV2 and CPE or carrageenan could elevate the survival rate. In this study investigated that seaweed polysaccharide extracts of ulvan, carrageenan, CPE for inhibiting influenza A virus infection on in vitro and in vivo model. In vitro, the batter inhibition effect of virus adsorption on influenza virus infection is during adsorption stage. In BALB/c mice animal model, the 6 weeks-old mice infecte with lethal doses influenza virus (100 PFU/mouse) and the mortality rate is 100%. The mice treatment seaweed polysaccharide extracts adsorption with virus before infection, the mortality rate of these mice are effectively reduced. The seaweed polysaccharide extracts also effectively decrease the production of proinflammatory cytokines and chemokines in the H1N1-infected mice. In summary, the seaweed polysaccharide extracts show a protective effect against virus infection on both in cell and animal experiment. Seaweed polysaccharides extract may be an ideal candidate worth while to develop into anti-viral agents.