Factors affecting the use of immunoosmophoresis for the detection of two insect riboviruses.

Some of the factors affecting the formation of precipitin lines during immunoosmophoresis were investigated using two unrelated insect riboviruses, Flock House virus (FHV) and cricket paralysis virus (CrPV). Precipitin lines formed in under 90 min. Concentrations of 200-400 ng/ml of FHV were routinely detected but occasionally the end-point was as low as 50 ng/ml. With CrPV, 1500 ng/ml was the routine detectable level. The sensitivity of the assay was largely unaffected by the presence of insect homogenate. Maximum detection of virus was obtained when the antigens and antibodies were at optimal proportion and excess of either reagent resulted in the blurring of precipitin lines. Immunoosmophoresis proved to be a rapid and inexpensive method of detecting negatively charged viruses in crude insect extracts and can, in some cases, have a sensitivity approaching that of more sophisticated serological techniques.