DETECTION OF SPONGOSPORA-SUBTERRANEA USING MONOCLONAL-ANTIBODIES IN ELISA

Five hybridoma cell lines secreting antibodies (MAbs) recognizing zoospores of S. subterranea were raised from splenocytes of mice. One MAb also weakly recognized plasmodia/zoosporangia and cystosori of S. subterranea, and another recognized only plasmodia/zoosporangia in plate-trapped antigen ELISA. Polymyxa graminis was recognized most strongly out of 26 micro-organisms other than S. subterranea against which the MAbs were tested. Most were recognized only weakly or not at all. The MAb that recognized zoospores of S. subterranea most strongly detected as few as three zoospores per microtitre plate well when 12 replicate wells per treatment were arranged randomly on plates and absorbance values subjected to analysis of variance. The sensitivity of detection was not improved by mixing antibodies, using a biotin-streptavidin amplification system, or by using a double antibody sandwich system. Zoospores of S. subterranea flushed from soil were detected only after unrealistically large numbers of cystosori had been added. They were not detected in samples of naturally infested soil removed from a field shortly after a severely scabbed potato crop had been harvested.