Humanized mice for Salmonella typhi infection: new tools for an old problem.

Salmonella enterica serovar Typhi (S. typhi), is a human restricted pathogen and the causal agent of typhoid fever. Although the use of antimicrobial drugs or vaccines has served as an effective therapeutics strategy against typhoid fever, the recent surge in multidrug resistant strains of S. typhi presents a major health concern worldwide. Progress on typhoid research has been limited in the past due to the lack of a suitable animal model that recapitulates the hallmark immunological features of human typhoid fever. We have recently developed a humanized immune system (HIS) mouse model that after intravenous challenge with S. typhi displayed classical manifestations of human typhoid fever including meningitis, liver pathology and mortality. Concurrent to our studies, two other groups also have developed humanized mouse models of S. typhi infections employing different protocols. All these recently adopted animal models of S. typhi infections provide promise for a new era of S. typhi research that may expedite detailed understanding of the cellular and molecular mechanisms of this bacterial infection and investigations of new antimicrobials and vaccines for effective control.