Effect of antiflagellar serum in the protection of mice against Clostridium chauvoei.

Specific antiflagellar serum of Clostridium chauvoei showed a powerful protective effect which prevented bacterial growth in the liver, but not in infected muscle, against intramuscular challenge with calcium chloride-activated spores in normal mice. No protective effect was observed in mice with polymorphonuclear leucocytes depleted by cyclophosphamide treatment. The antiflagellar serum had approximately the same protective effect in mice with macrophages blocked selectively by carrageenan as it did in normal mice. We suggest that the antiflagellar serum exerted its effect by opsonic function and that opsonized C. chauvoei was eliminated mainly by polymorphonuclear leucocytes rather than by macrophages.