Antigenic Properties of Bacillus Typhosus. 139 



77 («4i) 



Preliminary studies on the antigenic properties of different 

 strains of bacillus typhosus. 



By Sanford B. Hooker, (by invitation.) 



[From the Hearst Laboratory of Pathology and Bacteriology, Uni- 

 versity of California.] 



A search through the literature reveals no report of special 

 work upon antigenic differences among typhoid strains, although 

 serologic methods have frequently been used in differentiating 

 typhoid from closely allied organisms. The demonstration of the 

 severally specific antigenic individualities, notably of strains of 

 pneumococci, streptococci, gonococci, meningococci, and influenza 

 bacilli ; the fluctuant epidemiologic severity of typhoid fever from 

 time to time; the observation that antityphoid inoculation confers 

 no protection against paratyphoid infection; the growing list of 

 instances in which antityphoid inoculation has been unsuccessful, 

 the previously known and personally confirmed fact that a poly- 

 valent antigen is essential for good alexin fixation reactions in 

 typhoid fever are the main facts which have led to this investiga- 

 tion. 



Attention has been focused chiefly upon the delicately specific 

 method of alexin fixation as a means of detecting antigenic dif- 

 ferences. A considerable number of confirmatory agglutinin 

 absorption experiments have also been performed. 



Materials and Technic. — Of the 48 strains which have been used 

 21 are laboratory strains two to fifteen years old, and the rest have 

 been isolated and authenticated during the past year by Gay and 

 Chickering in the course of studies of local cases of typhoid fever. 



The antigens used were washed, formalized suspensions of 

 typhoid bacilli. These suspensions have been used also for im- 

 munizing rabbits, being eminently satisfactory for this purpose as 

 agglutinogens for agglutination and absorption tests. The total 

 volume of the fixation test has been one cubic centimeter, one fifth 

 that of the classical Wassermann. Sheep cells, rabbit anti-sheep 

 hemolysin, and guinea-pig serum make up the hemolytic system 



