Type I Interferon is Pathogenic During Chronic Mycobacterium africanum Infection.

Type I interferons (IFNs, including IFN-αß) contribute to the pathogenesis of Mycobacterium tuberculosis strains that induce high IFN-αß levels. In the current study we examined the role of IFN-αß during infection with a Mycobacterium africanum strain that induces low IFN-ß levels. We infected wild-type and IFN-αß receptor knockout mice with M. africanum and monitored bacterial growth, lung disease, and survival over 292 days. We found reduced lung bacterial burdens and less severe histopathological findings in the absence of IFN-αß signaling. We conclude that IFN-αß is pathogenic during chronic M. africanum infection and that the pathogenic effects may be mediated through poorer control of bacterial growth.