PRODUCTION OF CLEAR AND STERILIZED 

 ANTI-HOG-CHOLERA SERUM 



[preliminary paper] 



By M. Dorset, Chief, and R. R. Henley, Chemist, Biochemic Division, Bureau of 



A n im al I ndust ry 



INTRODUCTION 



In the United States the anti-hog-cholera serum of commerce for the 

 most part consists of the defibrinated blood of hyperimmunized hogs. 

 The red corpuscles contained in such commercial serum are not only 

 devoid of protective qualities but are objectionable for a number of rea- 

 sons. The practice of using the defibrinated hog's blood was adopted 

 because of the difficulty experienced in separating completely the clear 

 serum from the fibrin and the blood corpuscles. 



Hog blood, when allowed to undergo spontaneous coagulation, ordi- 

 narily yields but a small proportion of clear serum. In practice not 

 more than 30 or 35 per cent can be secured, the remainder of the serum 

 being held firmly within the large clot. If, instead of allowing the blood 

 to clot spontaneously, immediate defibrination be practiced, a yield of 

 defibrinated blood varying from 90 to 95 per cent may usually be obtained. 

 This defibrinated blood contains all of the antibodies present in the 

 blood when drawn, whereas, if the blood is allovv-ed to coagulate and the 

 separated clear serum alone is used, there must be a large loss of anti- 

 bodies, because part of the serum is held back in the clot. 



The occurrence of the foot-and-mouth disease in the United States 

 and the accidental infection of certain lots of hog-cholera serum and 

 virus with this disease have demonstrated the urgent need for some 

 method of treating these products which will serve to remove the possi- 

 bility of either of them being a medium for its dissemination. In order 

 to insure the freedom of hog-cholera serum from the virus of the 

 foot-and-mouth disease, it is not sufficient merely to filter the product 

 through bacteria-proof filters, because the virus of this disease itself is 

 known to pass through bacteria-proof filters. It is likewise known 

 that the virus of the foot-and-mouth disease is more or less resistant to 

 the preservatives which are commonly used and which are suitable 

 for the preserv^ation of serum. There seems to be, therefore, only one 

 means by which the serum may be sterilized in so far as the virus of 

 the foot-and-mouth disease is concerned, and thqt is by the application 

 of heat. The best European authorities state that this virus is killed 

 when heated at a temperature of 50° C. for 12 hours. It also seems 



Journal of Agricultural Research, Vol. VI, No. 9 



Dept. of Agriculture, Washington, D. C. May 29, 1916 



em A— 22 



(333) 



