%0 Journal Article %A Strange, R. E. %A Powell, E. O. %A Pearce, T. W. %T The Rapid Detection and Determination of Sparse Bacterial Populations with Radioactively Labelled Homologous Antibodies %D 1971 %J Microbiology, %V 67 %N 3 %P 349-357 %@ 1465-2080 %R https://doi.org/10.1099/00221287-67-3-349 %I Microbiology Society, %X SUMMARY: An assay for rapidly detecting and determining sparse populations of vegetative bacteria or bacterial spores (minimum number about 500; 2 to 4 x 10−10g. equivalent bacterial dry weight) is described. A sample is treated with 125I-labelled purified homologous antibody, filtered and washed on a Millipore membrane filter, and the radioactivity of the separated labelled immune complex is measured. The assay is specific, accurate and completed within 8 to 10 min. Sensitivity and accuracy decrease if the assay is applied to samples that contain particulate matter that non-specifically attaches antibody and is retained by a membrane filter. This type of interference is decreased by pretreating samples with clarified normal rabbit serum for a few minutes before assay. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-67-3-349