The effect of normal human serum on the mouse trypanosome Trypanosoma musculi in vitro and in vivo.

Trypanosoma musculi, a common blood flagellate found in mice, is similar in morphology and life cycle to the rat trypanosome T. lewisi . Both species belong to the subgenus Herpetosoma , and as T. lewisi has recently been shown to be a zoonotic pathogen, there is concern that T. musculi could also be potentially infective to humans. To test this hypothesis, a well-established method, the normal human serum (NHS) incubation test, was carried out which distinguishes human and non-human infective trypanosomes. We found that T. musculi could grow in 0.31% NHS in vitro , and even kept their infectivity to mice after incubation with 10% NHS for 24 h. In in vivo experiments, T. musculi were only slightly affected by NHS injection, confirming that it was less sensitive to the NHS than T. b. brucei , but more sensitive than T. lewisi . This resistance probably does not rely on a restricted uptake of ApoL-1. Due to this partial resistance, we cannot definitively confirm that T. musculi has the potential for infection to humans. As resistance is less than that of T. lewisi , our data suggest that it is unlikely to be a zoonotic pathogen although we would advise caution in the case of immunocompromised people such as AIDS and cancer patients. [ABSTRACT FROM AUTHOR]