514 THE TECHNIC OF COMPLEMENT-FIXATION REACTIONS 



Veterinarians are generally agreed that in contagious abortion of 

 cows the complement-fixation test is highly specific, and is frequently of 

 considerable value in establishing a diagnosis (Meyer and Hardenburgh 

 and others). 



Meyer and Boerner have found fixation of complement to occur in 

 contagious abortion of mares with an antigen of Bacillus abortus equi, 

 and recommend the test as diagnostic aid in this infection. 



Preparation and Standardization of Antigens. The antigen of 

 Bacillus abortus (Bang) for use in the complement-fixation test in 

 contagious abortion of cows is prepared by cultivating a number of 

 strains of the bacillus, which have been trained to grow aerobically, 

 upon slants of glycerin agar for seventy-two hours. The growths are 

 then washed off with sufficient normal saline solution containing 2 per 

 cent, phenol to yield a cloudy emulsion. Shake briskly in order to 

 break up the clumps of bacilli, and filter through paper. Place in a 

 refrigerator for several days to complete the sterilization, and titrate 

 the anticomplementary dose each time before the main test is conducted. 



The antigen may also be prepared by cultivating a number of strains 

 in glycerin-serum bouillon for five or six weeks. Centrifuge thoroughly 

 and wash the bacilli once or twice with normal saline solution, to remove 

 all traces of serum. Dilute the washed bacilli with sufficient normal 

 saline solution to give an emulsion equal in density to a twenty-four- 

 hour bouillon culture of Bacillus coli, and add 0.4 per cent, of phenol as a 

 preservative. 



The antigen of Bacillus abortus equi for making the complement- 

 fixation diagnosis of contagious abortion of mares is prepared of eigh- 

 teen- to twenty-hour-old glycerin bouillon cultures, with an addition 

 of 0.5 percent, of phenol. These antigens are less anticomplementary 

 than shake extracts, and keep their titer unaltered for many weeks 

 (Meyer and Boerner). They may also be used for making the mac- 

 roscopic agglutination test. These antigens may also be prepared 

 after the method used in the preparation of gonococcus antigen (page 

 506). 



The anticomplementary dose is determined each time, and one-half 

 this amount is used in performing the main test. The technic is the 

 same as that employed in the titration of glanders antigen. 



The tests and controls are conducted with descending doses of fresh 

 inactivated serum (0.05, 0.1, and 0.2 c.c.), in exactly the same manner 

 as the glanders reaction is performed. 



