Antibody Response to Neisseria Meningitidis Capsular Polysaccharide and Noncapsular Surface Antigens
Abstract
An indirect polysaccharide ELISA method that measured antibody
response to Neisseria meningitidis capsular polysaccharide was
modified to improve its sensitivity at high serum dilutions, to
shorten the overall time of the assay procedure, and to decrease
the background interference. The improved ELISA procedure was then
used to study the antibody response of 261 sera from Upper Volta,
Africa, to N. meningitidis group A capsular polysaccharide. An
attempt was made to correlate group A capsular polysaccharide
antibody levels of the Upper Volta sera to bactericidal and noncapsular
protein antibody levels of the same sera. The polylysine
precoat incubation time was shortened from 5 hours to 30 minutes
along with a considerable decrease in background interference and
an increase in sensitivity at high serum dilutions. No definite
correlation could be seen between the bactericidal titers and the
noncapsular protein and capsular polysaccharide antibody levels.
A polysaccharide ELISA specifically aimed at IgM antibodies was
used on some of the sera with promising results. It was concluded
that either the wrong antigens were chosen to be assayed, or
interference from some component of the test sera prevented the
showing of a positive correlation. The ELISA procedure worked very
well with the standard reference sera.