The Use of Antibody-sensitized Latex Particles to Detect Plant Viruses

In a previous paper (Abu Salih, Murant & Daft, 1968) we compared two highly sensitive serological tests, the passive haemagglutination (PHA) and bentonite flocculation (BF) tests, for detecting plant viruses. These tests depend on the attachment of either antigen or antibody to a carrier material (tanned red cells or bentonite particles). The PHA test was several hundred times more sensitive than the tubeprecipitin test and twenty to eighty times more sensitive than the BF test but had two main disadvantages. These were the short storage life of the red cells (which could be largely overcome by treating them with formalin) and the need to use high concentrations of antiserum globulin preparations to sensitize the red cells optimally. In contrast, bentonite particles could often be sensitized with lower concentrations of the serum globulin preparations and were stable for many months. Both kinds of sensitized carrier particles were time-consuming to prepare and some batches differed in behaviour from others.