A GUINEA-PIG MODEL FOR LYME-DISEASE

We report that outbred Hartley guinea pigs are susceptible to Borrelia burgdorferi. We recovered spirochetes from 57 of 60 (95%) guinea pigs inoculated when less-than-or-equal-to 3 months of age. In contrast, a nimals inoculated when greater-than-or-equal-to 6 months of age were r esistant to infection as defined by recovery of organisms at greater-t han-or-equal-to 4 weeks postinoculation. Infection was widely dissemin ated: B. burgdorferi was recovered from 83% of bladders, 64% of knee j oints, 57% of hearts, 48% of spleens, and 38% of spinal cords examined within 4 weeks of inoculation. Histopathologic changes were common in the heart (88%) (preferential involvement of perineural tissues near the annulus fibrosus) and bladder (76%) and were also noted in a minor ity of spinal cords (13%) and knee joints (9%). Western immunoblots de monstrated an immunoglobulin G response to B. burgdorferi, particularl y to the 24-, 31- (OspA), 39-, and 41-kDa (flagellin) antigens. Infect ion was cleared from most tissues with the passage of time; spirochete s were recovered from 63% of tissues removed from guinea pigs at less- than-or-equal-to 4 weeks after inoculation but from only 32% at greate r-than-or-equal-to 8 weeks postinoculation (P < 0.001). An exception w as the failure to clear spirochetes from infected knees, 90% of which were culture positive even when evaluated at greater-than-or-equal-to 8 weeks postinoculation. The guinea pig provides a new model useful fo r studying host-spirochete interactions in Lyme disease.