IMMUNOLOGICAL BEHAVIOR 1 Ot) 



Ty 159 mouse imdei^vent a considerable loss in aggliitinability 

 \vithoiit concomitant loss of neiitralizability of its reacting factors. 



The results of agglutination tests with the rough variants of 

 B. typhosus and the neutralization experiments indicated that the 

 anti-rough agglutinating and neiUralizing antibodies did not rini 

 parallel. In fact, Serum Horse.-, Bleedingii4 Avhich Avas not able 

 to neutralize consistently the reacting factors of strain Ty Tl 238 

 ser.2 had a higher agglutination titer than Serimi R-203 which 

 showed consistent neutralization of 43 reacting units of the same 

 filtrate. 



As previously noted, various degrees of neiitralizability exist 

 amono- roiiq-h variants derived from the same stock strain. There 

 appeared to be a parallelism between this and the aggliitinability 

 of the same variants by immune sera. (Horscir, vs. Ty Tl 238 ser.^ 

 and Ty Tl 245 ser.o.) 



No antigen analysis (i.e., somatic and flagellar antigens of Theo- 

 bald Smitii, etc.) of the various strains employed has been made 

 as yet. 



Serum precipitability of culture filtrates of various stock 

 strains and variants of B. typhosus and neutralizability of 

 reacting factors: 



A quantitative analysis of the results could not be safely made 

 since se\'eral dilutions of the antigens Avere not used in every in- 

 stance. The following was, hoA\e\er, concluded: 



The "rough" reacting factors which ^vere not neutralized by 

 anti-stock sera were also devoid of precipitinogens for these sera 

 (Ty Tl 238 ser.o and Ty Tl 245 ser.^ strains and Serum S.-,) . 



The appearance of neutralizing antibodies for the "rough" re- 

 acting factors was coincident ^vith formation of anti-"rough" pre- 

 cipitins (Ty Tl 238 ser.o and Ty Tl 245 ser.o and Serum R-303) . 



Abundant precipitation betAveen the filtrate and serum could 

 occur in spite of low neutralization (Ty 159 stock and Mouse^,; 

 and Serum Sn) . 



Virulence of B. typhosus variants and neutralizability of B. 

 typhosus reacting factors : 

 The various strains tested were transplanted into plain broth 

 pH 7.4. One c.c. of a broth culture previously diluted in sterile 

 plain broth 1:4 was injected intraperitoneally into each mouse. 

 It was necessary to test a large number of mice in x'lew of the 



