Digestion of Chlorella Cells by Chlorovirus-encoded Polysaccharide Degrading Enzymes

Using a halo-forming assay with polysaccharide-degrading enzymes encoded by Chlorella virus (chlorovirus) CVK2, several free-living Chlorella strains, especially those belonging to C. vulgaris, were found to be sensitive to the viral enzymes. Among these sensitive strains, a taxonomically established strain C. prototechoides 211-6 served as a new laboratory host for chloroviruses (NC64A-viruses). Many zoochlorella strains isolated from Paramecium were totally resistant to the enzymes. Attachment of CVK2 to the cells of both Chlorella strain NC64A and C. prototechoides 211-6 was markedly blocked by treatment of the cells with a mixture of the viral enzymes. The treatment with vAL-1 may destroy the virus receptor molecules.