Glycoprotein complexes were extracted from Phaseolus vulgaris var. Pinto infected with tobacco mosaic virus (TMV) or with tobacco necrosis, or after sham inoculation. After all three treatments there were two distinct periods when glycoproteins were at a maximum. The product accumulated during the primary response contained both β(1 → 3)- and β(1 → 4)-linked glucopyranosyl residues. That of the secondary response contained mainly β(1 → 4)- but no β(1 → 3)-linked residues. These two glycoprotein complexes were absent from healthy non-inoculated plants.The similarity between results from sham-inoculated plants and those inoculated with virus suggests that the glycoprotein formation is a wound response, induced through mechanical inoculations and not through virus infection. Deposition of glycoproteins within the cell walls in advance of infection may localize the virus by reducing the number of intercellular pathways for virus spread. If virus has already spread beyond the zone of cell wall modifications, localization will be incomplete.