SEQUENTIAL MEASUREMENT OF TOXOPLASMA-GONDII-SPECIFIC ANTIBODIES IN THE CEREBROSPINAL-FLUID OF CATS WITH EXPERIMENTALLY-INDUCED TOXOPLASMOSIS

Serum and cerebrospinal fluid (CSF) were sampled sequentially from sev en cats after primary and secondary inoculation with Toxoplasma gondii tissue cysts. Samples were assayed for T. gondii-specific immunoglobu lin M (IgM) and immunoglobulin G (IgG), and specific immunoglobulin ra tios were calculated to identify intrathecal antibody production. T. g ondii-specific IgM was not detected in the CSF of any cat. Local produ ction of T. gondii-specific IgG in CSF after primary and secondary ino culation was evident in four of seven cats (57%) and five of six cats (83%), respectively. These findings suggest that T. gondii infects the central nervous system in cats and activates local humoral responses. The cats in the study showed no neurologic signs of disease, which su ggests that a diagnosis of central nervous system toxoplasmosis in cat s should not be based solely on detection of intrathecally synthesized T. gondii-specific IgG.