Improvements in the Passive Hemagglutination Technique for Serological Detection of Plant Viruses

Abstract

The use of some samples of normal rabbit serum for diluting antigen in passive hemagglutination (PHA) resulted in nonspecific agglutination. Bovine serum albumin at 0.5% concentration prevented such nonspecific agglutination. The sensitivity of sheep red blood cells (RBC) treated with glutaraldehyde before they were tanned and sensitized was comparable to that of fresh RBC. Glutaraldehyde-treated cells could be preserved at 4-6.degree. C for 2 mo. without detectable loss in sensitivity. Better agglutination was obtained when sensitization of glutaraldehyde-treated cells with globulins was done at pH 7.0 rather than at 6.4 or 5.2. In comparative experiments, the sensitivity of PHA with purified peanut green mosaic virus was 40-80 times that of agar gel diffusion and precipitin ring tests, respectively. The minimum concentration of peanut green mosaic virus detected by PHA was 0.75 .mu.g/ml.