Studies on the Toxin of Aspergillus fumigatus

VIII. Biological properties of Asp-hemolysin

Abstract

Investigation was made on the biological properties of purified Asp-hemolysin isolated from the mycelium and culture filtrate of Aspergillus fumigatus.
Some differences were found in sensitivity of erythrocytes from various animal species to the hemolysin. Chicken erythrocytes were the most sensitive (MHD, 3μg), whereas frog erythrocytes were slightly hemolyzed (MHD, 2.5mg).
The minimum lethal dose of the toxin by the intravenous route was shown to be 750 and 250μg/kg of body weight for mice and chickens, respectively. Even a large dose (1g/kg) of the toxin had no lethal effect on mice when administered orally. The purified hemolysin was free from phospholipase C activity, as well as from dermonecrotic and hemorrhagin-like activities, which were found in crude extracts.
The hemolytic activity of Asp-hemolysin was activated a little by Zn²⁺, cholesterol and G-strophanthin. It was inhibited slightly by lecithin and Cu-chlorophyll, and remarkably by Hg²⁺, iodine and anti-Asp-hemolysin sera.
The hemolytic activity inhibited specifically by Hg²⁺ could be restored after addition of reducing agents, such as β-mercaptoethanol, cysteine and hydrosulfite. The hemolytic activity of this toxin was prevented distinctly when antitoxic serum was mixed with the toxin prior to the addition of an erythrocyte suspension, but indistinctly when antitoxic serum was added to a mixture of the toxin and this suspension. These biological activities of Asp-hemolysin were not lost by treatment with any of such proteolytic enzymes as trypsin, pepsin, papain and subtilin.