The Resistance of Four Mouse Lines to Bacterial Infection

Abstract

A comparison of Webster's selected, genetically heterogeneous resistant and non-resistant mice (here called mice A and B) has been made with two pure lines of mice (here called D and E) which were discovered to be similarly resistant and non-resistant to certain bacterial infections. In both cases, resistance and non-resistance were very marked characteristics when the infection in question was intraperitoneal inoculation with an organism of the Salmonella group; when the infective test dose consisted of intraperitoneal inoculations with a Pasteurella or Pneumococcus or of intracranial inoculation with the virus of louping-ill, these characteristics were no longer maintained, there being no certain difference in the mortality rates of the four mice lines.In an attempt to discover some factor which might help to explain the very notable differences in resistance to Salmonella infection which exist between these mouse lines, the normal antibody content of their sera was investigated.In experiments modelled on the bactericidal test, but possibly assessing rather the power of the sera to inhibit growth, it has been shown that both resistant races A and D possess this power to a much greater extent than do the two non-resistant races B and E.A further examination was the estimation of the antibody response after inoculation with killed Salmonella vaccine. So far as mouse numbers permit of judgment it was seen that the resistant race A produced a higher mean titre of H agglutinin than the non-resistant races B and E.