Hospital of The Rockefeller Institute for Medical Research.
J Exp Med. 1936 Aug 31;64(3):439-52. doi: 10.1084/jem.64.3.439.
Methods have been described by which the number of elementary bodies present in a suspension can be estimated. It has been shown that by means of replicate counts, in which the Petroff-Hausser chamber was used, a high degree of accuracy can be attained. By means of the Gates densitometer, the number of elementary bodies in a suspension can be determined with a coefficient of variation of about 3.0 per cent. A method has been described by which the accuracy of estimation of the infectious titer of a suspension can be increased without greatly enlarging the number of animals employed. This consists of selecting as the end-point that dilution of virus which on intradermal inoculation in a rabbit would lead theoretically to an equal number of positive and negative results. The statistical advantages of this method have been confirmed by the experiences of other laboratories. By the application of the methods described, there was shown to be a direct correlation between the number of elementary bodies and the number of infectious units of virus present in a given suspension. At the mean of the distribution this ratio is as the logarithms 9.62 to 8.0. To extrapolate this curve, in order to determine the number of elementary bodies present in a single infectious unit, while tempting, is probably not justifiable. It must likewise be remembered that the data given apply to a particular strain of vaccine virus, and that the number of infectious units has been determined by intradermal inoculation of rabbits. It appears also that this method may be of value in studies of the virulence of different strains of vaccine virus, since by its application one may determine not only the infectious liter of a suspension, but its content of elementary bodies. In the agglutination reaction it was found that optimum titers of serum were obtained when the test antigen contained from 2.0 x 10(9) to 1.05 x 10(10) elementary bodies per cc. Approximately 1.95 x 10(8) particles per cc. of suspension were required for the production of visible agglutination.
已经描述了一种可以估计悬浮液中存在的基本单位数量的方法。已经表明，通过重复计数，使用 Petroff-Hausser 室，可以达到很高的精度。通过 Gates 密度计，可以确定悬浮液中基本单位的数量，其变异系数约为 3.0%。已经描述了一种可以在不大大增加所使用动物数量的情况下提高悬浮液感染滴度估计准确性的方法。这包括选择作为终点，即病毒稀释度，在兔皮内接种时，理论上会导致阳性和阴性结果数量相等。其他实验室的经验证实了这种方法的统计优势。通过应用所述方法，证明在给定悬浮液中存在的基本单位数量和病毒的感染单位数量之间存在直接相关性。在分布的平均值处，该比例与对数 9.62 到 8.0 相对应。为了外推该曲线以确定单个感染单位中存在的基本单位数量，虽然诱人，但可能是不合理的。同样必须记住，给出的数据适用于特定的疫苗病毒株，并且感染单位的数量是通过兔皮内接种来确定的。似乎该方法在研究不同疫苗病毒株的毒力方面也可能具有价值，因为通过其应用，不仅可以确定悬浮液的感染滴度，还可以确定其基本单位的含量。在凝集反应中发现，当测试抗原中每 cc 含有 2.0 x 10(9)至 1.05 x 10(10)个基本单位时，血清的最佳效价最高。悬浮液中大约需要 1.95 x 10(8)个颗粒才能产生可见的凝集。
