In a previous experiment in human volunteers1 it was shown that frequent instillations of virus-free ultrafiltrate of trachomatous material caused trachoma-like clinical symptoms. However, this experiment was done before it was possible to cultivate trachoma virus; therefore, the circumstances were very much limited. The materials all were obtained from infected human conjunctivas. The control materials—in the strict sense, the normal human conjunctivas—were not available for the experiment. Thus, the experiment was lacking in indisputability.
Since 1957,2 trachoma virus has been cultivated in the yolk sac of fertilized eggs. Thus, any amount of the virus can be propagated in the laboratory, and, in addition, proper control materials are available. In the present experiment, therefore, the previous data were reexamined using egg-grown virus of trachoma.
Materials
Virus-Strains.
—Two strains of trachoma virus were used. The one is Mita-strain, which was isolated by us in Japan,3 and the other is