Inactivation of the influenza virus by low voltage roentgen rays.

A number of viruses have been subjected to various types of ionizing radiations in an attempt to correlate the structure of the elementary body with a given function. Some of the conclusions drawn from investigations on bacteriophage and animal viruses have been substantiated by other experimental methods. According to the target theory, the passage of an ionizing particle through a biological structure leads to a loss or change of function, and this effect of ionizing radiations on proteins, viruses, and bacteria is usually discussed in terms of sensitive targets or volumes. Experiments designed to estimate target size by irradiation inactivation are best performed with the agent in the dried state, so that the observed effects can be attributed to the direct ionization of the biological material. Lea (1947) states that the following results are to be expected when the action of the radiation is caused by a single ionization: (a) The survival curve is exponential with respect to the radiation dose; (b) The effect of a given dose of radiation is independent of intensity or the manner of fractionation; (e) To obtain the same degree of effect, the dose required with different radiations increases in the following order: gamma rays, hard X-rays, soft X-rays, neutrons, and alpha rays. When the effect of the irradiation is direct, the rate of inactivation generally follows the exponential law. If no equals the initial number of organisms and n the number which survive a dose D, the proportion of organisms not so far hit but which will be hit by an increment dD in the dose will be given by the formula -dn/n = dD/Do. The value Do is the dose required to score an