Properties of Monoclonal Antibodies to the Genus-specific Antigen of Chlamydia and Their Use for Antigen Detection by Reverse Passive Haemagglutination

Publisher Website
Google Scholar
Abstract
The chlamydial genus-specific antigen was extracted with phenol/chloroform/petroleum ether (PCP) from preparations of C. trachomatis and C. psittaci; quantities was measured using an assay for lipopolysaccharide (LPS). The LPS from C. trachomatis contained 2.2% (wt/wt) of ketodeoxyoctanoic acid. Five IgG monoclonal antibodies reacted in an ELISA (enzyme-linked immunosorbent assay) with LPS from both species, the antigen being periodate-sensitive and heat-resistant, confirming that all antibodies were againt the genus-specific antigen. All the antibodies bound to the PCP extract of C. trachomatis on an immunoblot, at a position corresponding to the periodate-Schiff-stained bands of both C. trachomatis extract and Salmonella Re-LPS. When linked to trypsin-treated sheep erythrocytes and used in reverse passive hemagglutination tests, all antibodies gave indicator cells capable of detecting chlamydial LPS or crude preparations of chlamydiae grown in McCoy cells, the sensitivity varying with the antibody used. The antibodies varied in IgG subclass (either IgG2, or IgG3), and in ability to precipitate in immunodiffusiontests. Two antibodies cross-reacted with 1 strain of Acinetobacter in ELISA and with Salmonella Re-LPS in both ELISA and immunodiffusion tests. The other 3 did not react in ELISA with Acinetobacter strains or Salmonella Re-LPS, and none of the 5 reacted with LPS of Escherichia coli or Pseudomonas mors-prunorum.