342 VETERINARY STATE BOARD 



tetanus and diphtheria. The antitoxin is also used as a prophy- 

 lactic agent. 



Define ctmboceptors, lysins, complement. 



Amboceptors are antibodies in serum which possess an afSnity 

 for both the complement and the cell to be destroyed (a bacterium 

 or a red blood-corpuscle), and which serves to unite the two, so 

 that lysis or destruction of the cell may be effected. It is also 

 called the immune body. 



Lysins are specific antibodies, formed in the blood-serum during 

 bacterial infection, which are destructive to the bacteria of the spe- 

 cific serum. They are probably identical with agglutinins. 



Complement is a thermolabile (altered or destroyed by heat) sub- 

 stance in normal serum which is destructive to bacteria and other 

 cells with which it is brought in contact by means of the amboceptor. 



(For further details, see Diagnosis of Glanders by Complement- 

 fixation Test, p. 167.) 



Discuss the serum therapy of hog cholera. 



It has been found that the serum from a hog which has recovered 

 from an attack of hog cholera possesses immunizing and curative 

 properties for susceptible hogs. If the hog which has recovered is 

 inoculated with the virus of the disease, its immunizing and curative 

 properties are greatly augmented, although the hog suffers no ill- 

 ness. This is called hyperimmunization. The hyperimnnmized hog 

 is bled, the blood defibrinated, and a small amount of a preservative 

 (phenol) is added to insure its keeping qualities. 



The use of serum as a curative agent is only of value in the early 

 stages of the disease. The serum is injected subeutaneously on the 

 inner side of the thigh in a dose of approximately 40 c.c. per 100 

 pounds of body weight. In recently infected or non-infected hogs 

 a passive immunity is secured which lasts only a few weeks, but is 

 sufSeient to protect against the effects of a transient exposure, as at 

 fairs, travelling, etc. 



How is hog cholera serum obtained? 



(See answer to preceding question.) 



Where serum is produced on a large scale, instead of utilizing 

 hogs which have survived a natural infection, susceptible hogs are 

 used. These are first given an immunizing dose of the serum as a 

 protective measure and later injected with gradually-increasing 

 doses of virus until they become hyperimmune (proven by test on 

 hogs) . They are bled from the tails at intervals of ten days so long 

 as their serum is potent. They may then be injected with virus and 



