STUDIES ON THE PHYSICAL AND CHEMICAL PROPERTIES OF THE VIRUS OF FOOT-AND-MOUTH DISEASE : III. RESISTANCE TO CHEMICALS.

The virus of foot-and-mouth disease exhibits a remarkable resistance to such bactericidal agents as the narcotic solvents (alcohol, ether, chloroform), or such antiseptics as phenol, bichloride of mercury, or cresol, as shown by tests made by others and ourselves. We have shown, however, that the resistance of the incitant to these chemicals is really masked. It is due to the fact that the reagents coagulate the proteins of the medium in which the virus is, as a rule, suspended. As a result the active agent is protected by the coagula which prevents direct contact with the chemicals. On the other hand, if advantage is taken of the periodic phenomenon attending such processes, and coagulation is prevented, the virus can then be brought under direct action of the antiseptics. Under these conditions, the incitant is more sensitive to destruction by the chemicals than is the living staphylococcus. As a corollary, the virus is destroyed as rapidly, or even more so, than are staphylococci by substances such as sodium hydrate (1 to 2 per cent solutions), or antiformin (1 per cent solution) which do not form coagula. We are therefore compelled to contradict the opinion that the extraordinary resistance to certain chemicals of the virus of foot-and-mouth disease, as it ordinarily occurs admixed with proteins, is an indication of its inanimate character. The results of a large series of experiments lead to the conclusion that of a number of antiseptics employed the sodium hydrate in 1 to 2 per cent solutions is an effective virucide. It is capable of killing the virus within 1 minute as shown by tests on cattle and guinea pigs. Furthermore, its effectiveness is not diminished even when the virulent material is admixed with cattle's urine, with manure, or with garden soil. The experimental evidence and the cheapness suggest its use in field practice as a disinfectant.