Intranasal inoculation of Mycoplasma pulmonis in mice with severe combined immunodeficiency (SCID) causes a wasting disease with grave arthritis.

Mycoplasma pulmonis or Myc. pneumoniae were inoculated intranasally to C.B-17 scid/scid mice (severe combined immunodeficient (SCID) mice). Immunocompetent C.B-17 mice were inoculated as controls. During the observation period of 5 weeks the mice were killed and necropsied. Mycoplasma pulmonis was recovered from all of the inoculated mice, and dissemination to various tissues increased with time. SCID mice, unlike immunocompetent mice, did not show lung lesions but exhibited severe inflammatory changes of the joints. Mycoplasma pulmonis, however, was isolated both from the lungs and the articular lesions. In addition, SCID mice infected for more than 3 weeks suffered from a pronounced loss of weight and emaciation. In the experiment with Myc. pneumoniae the agent could be reisolated, but lesions were not found in any of the infected mice. Mycoplasma pulmonis infection in SCID mice may be useful as a model of arthritis in immunodeficient humans.