4 BULLETIN TO, U. S. DEPARTMENT OF AGRICULTURE. 



EXPERIMENTS WITH DRIED GLANDERS BACILLI. 



The New York City board of health has been conducting immu- 

 nizing experiments with a vaccine prepared in their laboratory, con- 

 sisting of a suspension of dried glanders bacilli. Each cubic centi- 

 meter of the suspension contains 2 mg. of dried bacilli. Through the 

 courtesy of Dr. William H. Park, director of the laboratory, a suffi- 

 cient quantity of such vaccine was obtained for conducting a series of 

 investigations relative to the possibility of conferring immunity to 

 animals injected with this vaccine. 



GUINEA-PIG EXPERIMENTS. 



The experiments were made on guinea pigs and on horses. Twenty 

 guinea pigs, about 600 grams in weight, were divided into 4 groups, 

 4 pigs of each group receiving three immunizing injections of a definite 

 amount of vaccine at intervals of one week. The size of the doses 

 and other details are presented in Table 1. After the conclusion of 

 these vaccinations one pig from each group was subjected to infection 

 with suspensions of glanders bacilli. These injections with infectious 

 material were administered at various intervals. In all instances the 

 same strain of glanders bacilli was used for the infections. The fifth 

 pig in each group was not vaccinated, but served as a check, receiving 

 only a corresponding quantity of glanders bacilli. 



The results of these guinea-pig tests showed that there was not a 

 sufficient increased resistance among the vaccinated guinea pigs to 

 warrant any hopes of successful immunization by this method. It is 

 to be regretted, however, that in the infection of these pigs probably 

 too large a quantity of glanders bacilli was used. On the other hand, 

 it would appear that if there had been any appreciable immunity 

 present in the vaccinated guinea pigs they would have manifested it 

 by a greater resistance against the infection. 



