Postmortem Antigenic Epitope Retention of Galactose-N-Acetylglucosamine inBacillus anthracis-Infected Rhesus Monkey (Macaca multatta) Spleens

摘要

BACKGROUND: Anthrax bacilli can be identified by using a monoclonal antibody togalactose-N-acetylglucosamine, a Bacillus anthracis cell wall polysaccharide. We characterized the retention of antigenicity for this polysaccharide in prolonged postmortem autolysis of spleen from infected monkeys. EXPERIMENTAL DESIGN: Spleens from infected rhesus monkeys were allowed to autolyze for up to 30 days. To visualize the availability and retention of the polysaccharide at various days of postmortem autolysis, splenic tissue impressions were immunostained by silver enhanced immunogold (IGSS) using a monoclonal antibody against galactose-N-acetylglucosamine. RESULTS: All tissue had bacilli fragments of bacilli present from the day of necropsy through 30 days postmortem observation. Consistent immunocytochemical staining of bacilli occurred from day 3 to 15. In some cases, bacilli stained positive as late as 30 days. Extracellular stain reaction product demonstrating specific immunoreactivity was also noted as heavy in day 0 samples and gradually diminished over time to the day 15 samples. CONCLUSIONS: The antigenic epitope recognized by the monoclonal antibody against galactose-N-acetylglucosamine was preserved with consistency for 15 days postmortem in decaying splenic tissue. Membrane bound polysaccharide did not appear to be consistently available to antibody for reaction product formation until 3 days postmortem. The polysaccharide appears to also exit free of the bacillus cell wall, showed strong immunostaining properties during early postmortem decay.