A novel enzyme immunoassay commonly applied for ten strains of Pyricularia oryzae.

Abstract

Antiserum against a strain of the rice blast fungus Pyricularia oryzae was elicited in rabbits immunized with its cell fragments emulsified with incomplete Freund's adjuvant. The fragments were also used as solid-phase antigens. A highly sensitive, competitive type enzyme-linked immunosorbent assay for P. oryzae was developed by using these two preparations as the immune reagents together with the use of beta-D-galactosidase-labeled anti-rabbit IgG as the tracer. Cross-reactivity of nine different strains of P. oryzae were measured by the assay. Sensitivity and accuracy of the assay was improved by choosing the cell fragments of the least cross-reactive strain as the solid-phase antigen. The improved method was successfully applied for sensitive and accurate assay of all ten strains of P. oryzae with the common measuring range between 1 and 100 ng per tube. Other species of microorganisms had little reactivity in this immunoassay indicating that the assay is specific to P. oryzae group microorganisms.