Host specificity of cloned Spironucleus sp. originating from the European hamster

In vivo experiments with a clone of the intestinal flagellate Spironucleus sp. originating from the laboratory European hamster (Cricetus cricetus), and the comparison with a spontaneous infection from laboratory bred European hamsters suggest high specificity of this clone for the homologous host. Only the Syrian golden hamster (Mesocricetus auratus) could be infected experimentally, though the mean intensity of infection was lower. Other heterologous recipients, mice and rats of one outbred and one inbred strain each, could not be infected. Even immunodeficient mice (athymic and C.B-17-scid) remained uninfected after inoculation of 5 x 10(5) cysts per mouse. This is the second Spironucleus clone, after the rat isolate (Schagemann et al., 1990), with a high level of host specificity suggesting heterogeneity within the genus Spironucleus.