Detection of Neisseria meningitidis cell envelope antigen by enzyme-linked immunosorbent assay in patients with meningococcal disease.

Sera from various populations and cerebrospinal fluid (CSF) from meningitis patients were tested for Neisseria meningitidis cell envelope antigen by an enzyme-linked immunosorbent assay (ELISA) sandwich system. The minimum optical density (OD) for antigen detection in CSF was defined as the mean value obtained with specimens from a group of tuberculous meningitis patients plus two standard deviations. By this criterion, antigen was detected by ELISA in four of five CSF specimens from group A meningococcal meningitis patients. Very high ELISA values were obtained with sera from fulminating cases but control sera and sera obtained from meningococcal meningitis non-fulminating cases could not be clearly differentiated by this technique. The possible reasons for this are discussed. The results of this study show that as little as 15 ng/ml (protein) of cell envelope antigen can be detected by the ELISA sandwich test and suggest that the technique may be of value in clinical diagnosis of meningococcal disease.