Page 75 - Human Lyme Neuroborreliosis

Non-human Primate Animal Models 59

endoneurium, and epimysium and endomysium, as well as, in leptomeninges
and nerve roots but not in CNS parenchyma consistent with the usual
presentation of headache, meningismis or radiculopathic symptoms. The
localization of spirochetes in CNS of humans has rarely been described using
nonspecific silver impregnation [20, 21, 22] revealing a positivity of PCR-
ELISA in samples from cerebrum and brainstem were likely to be
leptomeningeal rather than parenchymal in localization.

Bai and colleagues [23] provided additional insight into spinal cord
involvement in the NHP model of LNB in a study of 25 adult rhesus monkeys
inoculated with Bb sensu stricto strains N40 or 297 by needle or tick
inoculation, or Bb genospecies B. garinii Pbi, 793, or Pli, by needle. Two of
the NHP were immunocompetent; all others were immunosuppressed with
dexamethasone transiently during the first month of infection or permanently
for the duration of infection lasting 2 to 4 months before postmortem
examination. Spinal cord tissue was processed for RNA extraction and
histology, and comparisons of spirochetal load in different regions of the
spinal cord including meninges, dorsal root ganglia and motor and sensory
nerve roots. Serum ELISA, Western blots, and immunohistochemistry were
performed for detection of B. burgdorferi using hyperimmune serum from a
rabbit persistently infected with B. burgdorferi strain N40 using negative
controls, and rabbit polyclonal antibody antihuman immunoglobulins, B- and
T-cells, C1q and C5b-9. Total RNA was extracted and reverse transcription
(RT) was performed as well as PCR amplification for rhesus genes using Taq
DNA polymerase and human C1q beta chain sequences. DNA sequencing was
performed after RT-PCR amplification using Borrelia Taqman probes. Viable
spirochetes were identified only in tissue culture from immunosuppressed
NHP but not in any of the cultures from transiently immunosuppressed or
immunocompetent NHP. Serum ELISA showed that all NHP inoculated with
B. burgdorferi sensu stricto strain N40 by syringe or tick developed specific
antibody, compared to only one of the two NHP inoculate with B. burgdorferi
strain 297 and 4 of 10 NHP inoculated with B. garinii strains. All
immunocompetent and transiently immunosuppressed NHP inoculated with
N40 or 297 showed positive Western blot results. One animal inoculated with
the B. garinii strain Pbi showed mild mononuclear meningoradiculitis with
inflammatory infiltration along the entire neuraxis including the brain,
brainstem, spinal cord, spinal nerve roots and dorsal root ganglia, however
microscopic examination failed to reveal inflammation in the remaining 24
NHP. The inflammatory cell infiltrate in that animal was composed of T-cells
and plasma cells, rare B-cells and macrophages, with local deposition of IgM,

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