476 MICROBIOLOGY OF SPECIAL INDUSTRIES. 



In re-hyperimmunizing, about one half the quantity of virus used 

 in the first process is usually injected. The animal may be re-hyper- 

 immunized two or three times or until it appears to be exhausted. It is 

 then relieved of all of its blood. As a rule the different lots of serum 

 representing the different bleedings from the same hyperimmune hog 

 are mixed and the whole subjected to test. In order to test the potency 

 of the product four susceptible pigs, each weighing about 26 kg. 

 (50 pounds) are inoculated subcutaneously, each with 2 c.c. of virus. 

 Two of these pigs are simultaneously injected, each with about 20 c.c. 

 of the serum under test. If the hyperimmune serum possesses activity 

 the two test pigs should remain in a normal condition throughout, except 

 for the presence of a thermal reaction and slight clinical symptoms, 

 while the two control pigs should show severe symptoms in five or six 

 days and should die in less than fifteen days. 



The practical method of treatment in the field consists in the simulta- 

 neous intramuscular injection of the hyperimmune serum and virus into 

 healthy hogs. The amount of hyperimmune serum which should be in- 

 jected varies from 10 c.c. to 70 c.c., depending upon the weight of the hog 

 to be treated. Thus, a hog weighing 34 kg. to 45 kg. (75 to 100 pounds) 

 usually receives 20 c.c. of serum, together with 2 c.c. of virus. The 

 usual dose of virus for hogs above 34 kg. (75 pounds) weight is 2 c.c. 

 For pigs weighing less than 34 kg. (75 pounds) 1/2-1 c.c. of virus 

 should be injected. 



ANTHRAX VACCINE. While several experimental and practical 

 methods have been used in vaccinating against anthrax, probably the most 

 important, at present, is that devised by Pasteur. This method consists 

 in the use of cultures which have been attenuated by growth on artificial 

 culture media at temperatures above the optimum. The inoculation 

 of such attenuated cultures into healthy animals results in active 

 immunization (page 603). 



The stock culture of Bad. anthracis is usually obtained from the blood 

 of a typical case of anthrax. The culture is transferred to agar or broth 

 and incubated. Two vaccines are prepared, the first being less active 

 than the second. Vaccine No. i is made by placing in suspension in 

 sterile, physiological salt solution or other liquid, the anthrax organisms 

 which have been grown at a temperature of 42 for a period of fifteen 

 to twenty days. Vaccine No. 2 consists of a similarly treated culture 

 of Bad. anthracis which has grown at a temperature of 42 for ten 



