Sandwich Enzyme Immunoassays for Detection of Salmonella Typhi

Abstract

Enzyme immunoassays were developed using monoclonal antibodies raised against somatic (O), flagellar (H) and capsular (Vi) antigens of Salmonella typhi. The assay based on anti-O monoclonal antibodies could specifically detect S. typhi and soluble lipopolysaccharide (LPS) isolated from S. typhi. Anti-H MoAbs detected motile S. typhi and soluble flagellar antigen. Monoclonal antibodies against capsular polysaccharide could detect Vi-containing S. typhi as well as soluble Vi antigen. The three assays reported here detected S. typhi with 100% sensitivity in blood culture broths obtained from bacteriologically confirmed typhoid patients and were negative with blood specimens containing Salmonella senftenberg, E. coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis or Streptococcus (α - hemolytic) derived from patients with pyrexia. The assays, however, did not demonstrate the presence of soluble antigens in sera and urine samples obtained from typhoid patients.