Localization and persistence of spiroplasmas in an experimental brain infection in suckling rats.

The GT-48 strain of Spiroplasma mirum was employed in an experimental brain infection in 1-day old suckling rats in order to define the localization and persistence of organisms in brain and spleen and to evaluate the responses of three distinct genetic lines of rats. Rat pups inoculated intracerebrally with 30-300 organisms exhibited peak infections at 15-20 days post-inoculation, while challenge levels of 3-30 organisms showed some persistent infections for as long as 60 days. The responses of three genetic lines of rats to the experimental spiroplasma infection did not differ significantly over a 60-day follow-up period. The acute-phase infection in suckling rats showed a rapidly developing and widespread dissemination of organisms to all major areas of the brain.