736 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



TUBERCULOSIS VACCINE. Among the experimental products for 

 the prevention of animal tuberculosis may be mentioned von Behring's 

 " bo vo- vaccine." The technique involved in the preparation of this 

 vaccine is not generally known. Romer* describes the material as 

 being composed of the living tubercle organisms which are dried for a 

 period of thirty days in sealed glass tubes. After this process of attenua- 

 tion the organisms are injected, in carefully graduated doses, into 

 healthy calves. Field tests which have been made upon calves with 

 bo vo- vaccine indicated unsatisfactory results. 



In human practice various tuberculins prepared both from the 

 bouillon culture and from the cellular elements of Bact. tuberculosis 

 are used as therapeutic and diagnostic agents. Products containing 

 the cellular elements are similar in nature to bacterial vaccines. 



BACTERIAL VACCINES (BACTERINS) 



Opsonins may be defined as the elements in the blood or body fluids 

 which are capable of modifying invading bacteria in such a way that 

 they become ready prey to the leucocytes. In the presence of opsonins, 

 therefore, phagocytic activity is increased. Opsonins are apparently 

 distinct from agglutinins, lysins, and other analogous substances, 

 because different degrees of heat are necessary for their destruction. 

 Moreover, a given serum may agglutinate, or may exert lytic action, 

 without possessing opsonic activity. 



Wright and Douglas first advanced the theory of opsonic action, and 

 suggested that the subcutaneous injection of a given species of bacteria, 

 killed by heating, caused the blood of the treated individual to exert 

 greater opsonic activity toward the species of organisms in question. 

 The results of the work of others proved to be confirmatory. 



To prepare a bacterial vaccine, the specific organism is isolated and 

 after being grown for twenty-four hours or longer at a temperature of 

 37, it is emulsified in sterile physiological salt solution, heated at 

 approximately 60, or killed by the use of chemical agents, standardized 

 as to the number of bacteria present in i c.c. of the emulsion, and a 

 preservative added. 



If the patient and attending physician are conveniently situated in 

 respect to a laboratory, the "opsonic index" may be taken before and 

 during the treatment. This consists in the determination of the aver- 



* Romer, Beitrage z. Exp. Therapie. 1904, J. 



