Detection of antibodies to Brucella cytoplasmic proteins in the cerebrospinal fluid of patients with neurobrucellosis

Abstract

The diagnosis of human neurobrucellosis usually relies on the detection of antibodies to Brucella lipopolysaccharide (LPS) in cerebrospinal fluid (CSF) by agglutination tests or enzyme-linked immunosorbent assay (ELISA). Here we describe the detection of immunoglobulin G (IgG) to cytoplasmic proteins (CP) of Brucella spp. by ELISA and Western blotting in seven CSF samples from five patients with neurobrucellosis. While IgG to CP (titers of 200 to 12, 800) and IgG to LPS (800 to 6,400) were found in the CSF of these patients, these antibodies were not detected in CSF samples from two patients who had systemic brucellosis without neurological involvement. The latter, however, had serum IgG and IgM to both LPS and CP. No reactivity to these antigens was found in CSF samples from 14 and 20 patients suffering from nonbrucellar meningitis and noninfectious diseases, respectively. These findings suggest that, in addition to its usefulness in the serological diagnosis of human systemic brucellosis, the ELISA with CP antigen can be used for the specific diagnosis of human neurobrucellosis.

FIG. 1

IgG reactivity to Brucella CP and LPS in CSF samples from noninfected subjects and from patients with neurobrucellosis, systemic brucellosis without neurological involvement, or nonbrucellar meningitis. Anti-CP and anti-LPS reactivities were determined by indirect and antigen capture ELISAs, respectively.

FIG. 2

IgG reactivity to Brucella CP in CSF samples from patients with neurobrucellosis as assayed by Western blotting. Proteins were electrophoresed in 15% polyacrylamide gel in the presence of sodium dodecyl sulfate, transferred to nitrocellulose, and reacted to CSF diluted 1:20. Lanes 1, 2, 3, 5, and 7, diagnostic samples from patients 1 to 5, respectively; lane 4, sample taken from patient 3 60 days later; lane 6, sample taken from patient 4 30 days later.