In-vitro characterisation of the phagocytosis and fate of anthrax spores in macrophages and the effects of anti-PA antibody.
Antibodies (Abs) to the protective antigen (PA) component of the anthrax toxins have anti-spore as well as anti-toxin activities. Anti-PA antisera and purified anti-PA Abs enhance the phagocytosis by murine-derived macrophages (MQs) of spores of the Ames and Sterne strains and retard the germination of extracellular spores in vitro. The fate after phagocytosis of untreated and anti-PA-treated spores was further studied in culture medium that supported phagocytosis without stimulating spore germination (Dulbecco's minimal essential medium with horse serum 10%). The spores germinated within cells of primary peritoneal murine MQs (C3H/HeN) and MQs of the RAW264.7 MQ-like cell line; germination was associated with a rapid decline in spore viability. Exposure of MQs to inhibitors of phago-endosomal acidification (bafilomycin A and chloroquine) reduced the efficiency of MQ killing and allowed outgrowth and replication of the organisms. Treatment of spores with anti-PA Abs stimulated their phagocytosis and was associated with enhanced MQ killing of the spores. The enhanced killing of spores correlated with the greater extent of germination of anti-PA-treated spores after phagocytosis. A PA null mutant of the Ames strain exhibited none of the effects associated with anti-PA Ab treatment ofthe parental strain. Thus, the anti-PA Ab-specific immunity induced by vaccines has anti-spore activities and its role in impeding the early stages of infection with Bacillusanthracis needs to be assessed.
Welkos
S
S
Friedlander
A
A
Division of Bacteriology and *Headquarters, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD 21702-5011, USA.
Weeks
S
S
Little
S
S
Mendelson
I
I
Division of Bacteriology and *Headquarters, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD 21702-5011, USA.
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000907:Antibodies, Bacterial / Q000494:pharmacology; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology; D001408:Bacillus anthracis / Q000276:immunology* / Q000472:pathogenicity; D001427:Bacterial Toxins / Q000235:genetics / Q000276:immunology; D002460:Cell Line; D002738:Chloroquine / Q000494:pharmacology; D005798:Genes, Bacterial; D066298:In Vitro Techniques; D018942:Macrolides; D008264:Macrophages / Q000187:drug effects / Q000276:immunology* / Q000382:microbiology*; D051379:Mice; D008809:Mice, Inbred C3H; D009154:Mutation; D010587:Phagocytosis / Q000187:drug effects; D013171:Spores, Bacterial / Q000276:immunology
D000900:Anti-Bacterial Agents; D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D018942:Macrolides; C030325:anthrax toxin; D002738:Chloroquine; C040929:bafilomycin A1