Abstract
Polystyrene microtitre plates coated with bovine C1q were used to trap antigen: antibody aggregates of three plant viruses [plum pox virus (PPV), potato virus Y and cocksfoot mild mosaic virus] and human antibody aggregates in an ELISA-type system. The aggregates were detected with alkaline phosphatase-labelled anti-rabbit or anti-human IgG. The assay was as sensitive as the double antibody sandwich method of ELISA for the detection of PPV particles; the limit of detection was 4 to 15 ng virus/ml in purified preparations or a dilution of > 1/1000 in infective Nicotiana clevelandii sap extracts. When used at low dilutions, plant sap of three of the four species tested had an inhibitory effect on the reaction.