Antiviral activity of polysaccharides against infection of tobacco mosaic virus

Abstract

AbstractIn the course of searching for antiviral substances to tobacco mosaic virus (TMV), it was found that polysaccharides have a high inhibitory activity against TMV infection. The leaves of Xanthi NN tobacco were rubbed with the mixtures of TMV and polysaccharides such as chondroitin sulfate C‐ and A‐ types. The addition of polysaccharides to the inoculum solution greatly reduced the number of local lesions formed on the inoculated leaves. Here the polysaccharide did not completely prevent virus entry into the leaves and the virus particles may penetrate and multiply in leaves without forming lesions. Although the electron micrograph showed that the virus suspension was almost monodisperse, the addition of polysaccharides caused TMV to form large raft‐like aggregates. The TMV solution became turbid after the addition of a large amount of polysaccharides. A threshold concentration of polysaccharides exists for virus precipitation, which is independent of the virus concentration. The size of polysaccharide at the threshold concentration agreed well with that obtained by light scattering method. The strength of the interaction between TMV and polysaccharides was found to be related to the degree of inhibitory activity of polysaccharides.