Inoculation of nonhuman primates with the N40 strain of Borrelia burgdorferi leads to a model of Lyme neuroborreliosis faithful to the human disease.

We injected rhesus macaques with a highly infective strain of Borrelia burgdorferi to assess whether experimentally inoculated nonhuman primates (NHPs) could serve as models of human Lyme neuroborreliosis (LNB). The animals developed biopsy-confirmed erythema migrans in the area of the inoculations. ELISA testing of sera revealed strong antibody reactivity to B burgdorferi antigens, and Western blotting showed that 16-, 22-, 31-, 34-, and 41-kd proteins of the spirochete were major antigens recognized by antibody. Culture and polymerase chain reaction (PCR) testing of serial CSF specimens revealed that chronic infection of the CNS occurred in all NHPs injected. CSF pleocytosis occurred concurrently with CNS infection. Brain MRI revealed intense meningeal inflammation in one NHP as manifested by gadolinium uptake by the dura at the base of the temporal lobes. All animals had measurable antibody in the CSF after invasion. These studies are the first to demonstrate that experimental LNB in NHPs is a reliable model faithful to the human disease, with spirochetal invasion of the subarachnoid space. This also is the first report of CSF samples positive by culture in experimental LNB. Inflammation in the CNS as manifested by CSF pleocytosis and MRI findings was also correlated with the presence of spirochetal DNA detected by PCR. These data support the hypothesis that the pathogenesis of LNB is associated with direct spirochetal invasion, and provide evidence that CNS involvement is more common than heretofore thought.