The Effective Dose ED method

Advantages of this method are the improvement in the reproducibility of the test, which renders possible the detection of subtle seroconversions, and the linear proportionality between the ED results and the titres. Disadvantages of this method are the considerable work and the amount of reagents involved and the uncommon way of expressing the results, i.e. in Brigg s logs (e.g., for acute phase serum, ED = —80 for convalescent phase serum ED = 1.07). This method also assumes parallelism of the dose-response curves. 

A similar approach was adopted by Soula et al. (1982) except that the titre was expressed as ELISA (50%), obtained after transformation of the sigmoidal curve into a linear response curve (according to the methods discussed in Section 15.2.5). 

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