The Preparation Of Chitosan And Its Derivatives And Their Inhibition Effect On Newcastle Disease Virus

Newcastle disease(ND) is an acute septic and contact susceptible infectious disease caused by Newcastle disease virus(NDV). It resulted in blooding in respiratory tract and digestive tract mucosa. Currently, the treatments against ND mainly adopts the prevention methods—— vaccines. In recent years, a large number of studies have shown that marine polysaccharide has antiviral activity and improve the body immunity. Chitosan as an only positively charged natural polysaccharide has terrific biological activities, such as the increase of immunity, antitumor, antibacterial, lipid-lowering and moisturizing. What’s more important, it’s found that chitosan and its derivatives can inhibit dozens of plant virus and viroid infection. But if it against NDV has not been reported.Therefore, we took chitosan with different molecular weight(Mw), different modified groups and different form as research objects in this article to select the best product against Newcastle disease virus. The results indicated by the hemagglutination titer of allantoic fluid in chicken embryo. At the same time, using the fluorescent quantitative PCR technology, we detected the change of immune factors in order to determine that if the chitosan derivatives has activated and regulated the immune system in the process of antiviral. It’s useful to determine the influence of chitosan derivatives on the body’s immune system and its efficacy mechanism. Specific results are as follows:All test samples have antiviral activity against NDV influenced by Mw, modified group, the concentration of the product and the way of vaccination significantly. 1) Chitosans with different Mw and concentration have different antiviral activity and the best Mw of α-chitosan and β-chitosan are 4513 Da and 5743 Da respectively in a dose-dependent manner; 2) β-chitosan’s antiviral activity is superior to α-chitosan. When the Mw was 3 kDa-6 kDa, it reduced blood clotting titer to 0; 3) 6-deoxidationN-phthalic acyl chitosan and 6-deoxidation-6-bromine-N-phthalic acyl chitosan have better antiviral activity than degraded α-chitosan and β-chitosan which reduce blood clotting titer to 0.Results from fluorescence quantitative PCR showed that both α-chitosan and β-chitosan effectively increased the transcription of immune factors such as IL-2, IFN-β, TNF-α, IFN-α, while did not lead to a sharp decline in viral RNA. Amine modified chitosan has a significant effect on the gene expression of immune factors and reduced the viral RNA effectively. This article made it possible to obtain a green, inexpensive and effective drug against NDV. At the same time, it also made an important foundation for the systemic research of the treatment of other immune injury disease.