Riley J M, Campbell W E, Orlando M D, Shirey W N, Dorsey W G
Appl Microbiol. 1967 May;15(3):606-10. doi: 10.1128/am.15.3.606-610.1967.
When suspensions of psittacosis organisms were injected intracerebrally into groups of mice, a nearly linear relationship was observed between the concentration of the organisms injected and the mean time to death of the mice. Thirty-four psittacosis preparations were assayed and, by plotting the relationship between the reciprocal time to death for mice given the 10(-3) dilution of agent against the number of mouse intracerebral median lethal doses (MICLD(50)), a reference curve was established. By use of this reference curve, it was possible to estimate directly the LD(50) value of a psittacosis suspension of unknown concentration from the mean reciprocal time to death of a group of mice injected with a single dilution. By this procedure, the number of mice used was reduced by 62.5%, the titrations were completed in 3 to 5 days as compared with the usual 12 days, three to four times as many assays could be done in 1 day, and no assays had to be repeated. In addition, the precision of the single-dilution assay compared favorably with that of the LD(50) titration.
将鹦鹉热病原体悬液脑内注射到几组小鼠体内时，观察到所注射病原体的浓度与小鼠平均死亡时间之间存在近乎线性的关系。对34份鹦鹉热制剂进行了测定，并通过绘制接受10⁻³稀释剂的小鼠的死亡时间倒数与小鼠脑内半数致死剂量数（MICLD₅₀）之间的关系，建立了一条参考曲线。利用这条参考曲线，就可以根据注射单一稀释液的一组小鼠的平均死亡时间倒数直接估算出未知浓度的鹦鹉热悬液的LD₅₀值。通过这个程序，使用的小鼠数量减少了62.5%，滴定在3至5天内完成，而通常需要12天，1天内可以进行的测定次数是原来的三到四倍，而且无需重复测定。此外，单稀释测定的精密度与LD₅₀滴定法相比毫不逊色。
