Suitability of dyed latex bead agglutination test for immunodiagnosis of Karnal bunt (Tilletia indica) teliospores in a single seed of wheat

The immunodiagnosticum for this test was prepared extempore by mixing blue color dyed latex beads (1% suspension) with equal volume of diluted anti-teliospore serum. This test was considered to be better for the detection of solubilized teliosporic antigens over intact teliospores of Karnal bunt. The teliosporic antigens solubilized using sonication and detergent extraction were used for the standardization of the test by optimizing the dilution of latex bead suspension and determining the detection limits. For determining the sensitivity of test, antigen concentration kinetics analysis was performed by adding 15 µl of antibodies sensitized latex beads to 15 µl of different concentrations of solubilized antigens on glass slide. The detection limit of this test was 7.5 µg solubilized teliosporic antigens equivalent to 750 teliospores and suitable for single seed analysis. Small agglutinin formation with solubilized antigen of Puccinia recondita and T. barclayana interpreted on the basis of partial cross reactivity of immunodignosticum with these pathogens. However, no cross reactivity was found with teliosporic antigen(s) of spores of Curvularia lunata, Ustilaga tritici, Helminthosporium sativum, Ustilaginoidea vircns and Alternaria triticina.