An enzyme-linked-immunosorbent assay method for detection of immunoglobulins to pertussis toxin.

A microplate enzyme-linked-immunosorbent assay (ELISA) for detection of antibodies against pertussis toxin, using fetuin as a spacer-layer between the solid phase and pertussis toxin, was compared to a method using pertussis toxin alone as antigen. Antibodies of IgG, IgM and IgA classes were studied in paired human sera. Raised antibody levels were demonstrated for ten children suffering from whooping cough. Antibody levels in sera from 20 healthy 4-year-old children showed high correlation to earlier experienced pertussis. No significant antibody titer changes against pertussis toxin were seen in children with adenovirus infection. The investigation shows that precoating with fetuin improves the sensitivity of the method as much as 5-30 times and makes the method useful in serological diagnosis of whooping cough.