Genetic control of susceptibility to group A streptococcal infection in mice

The influence of genetic background on the ability to control infection wit h group A streptococci was investigated in different inbred strains of mice . Whereas BALB/c, C57BL/10, and DBA/2 mice were the most resistant strains, with lower bacteria loads and higher survival times, C3H/HeN and CBA/J mic e exhibited substantially higher bacterial growth and 100% mortality. Diffe rences in susceptibility were not dependent on the inoculum size, Resistanc e was influenced by sex, with males being much more susceptible than female s. B cell- and T cell-deficient mice from the resistant background were as resistant to infection as were immunocompetent mice, which suggests that th e effector mechanisms are independent of adaptive immunity. These results d emonstrate for the first time the influence of genetic background and sex o n susceptibility to infection with Streptococcus pyogenes in mice. The use of this mouse model of group A streptococcal infection will allow for a bet ter definition of parameters involved in the outcome of the disease.