ASO Procedure and Interpretation

Preparation for the Assay

  1. Allow all reagents and samples to warm to room temperature (20-30°C) before use. Remove reagents from foam holders. Do not heat reagents in a water bath.
  2. All reagents are ready for use as supplied. Gently mix the reagents before use; avoid foaming.
  3. Gently mix the LATEX REAGENT before each use to ensure homogeneity.

Assay Protocol - Qualitative

  1. Using the stirrer pipets, deliver one free-falling drop (0.03 ml) of each serum sample onto a separate circle on the test slide. Use a fresh stirrer pipet for each sample. When using the stirrer pipet, keep it in a vertical position to ensure accurate delivery. Repeat by adding one free-falling drop of REACTIVE or NONREACTIVE CONTROL from the dropper vials supplied. Note the location of each sample by using the numbers located above and to the left of each circle.
  2. Expel the contents of the LATEX REAGENT dropper and refill. Add one drop of the reagent to each serum specimen and to each control.
  3. Using the flat end of the stirrer pipets, mix each specimen and control serum with the LATEX REAGENT, in a circular manner, over the entire area in the circles of the slide.
  4. Gently tilt and rotate the slide for two (2) minutes and observe for agglutination. All test results should be compared to both REACTIVE and NONREACTIVE CONTROLS.
  5. Wash the glass slide(s) with detergent and rinse with distilled or deionized water for future use.

Assay Protocol - Semiquantitative

Prepare serial dilutions of patient serum, in saline, in test tubes as follows:

ASO chart of serial dilution ratios
Testing on additional dilutions should be performed as needed.

Using each dilution as a separate test specimen, apply the samples to the slide as described in Step 1 of the Qualitative Assay Protocol and proceed with Steps 2 through 5 of the Qualitative Assay Protocol. Include undiluted sample if not tested previously on that day with the same lot of LATEX REAGENT.

ASO image showing positive and negative results.