HIRSUTELLIN-A, A TOXIC PROTEIN PRODUCED IN-VITRO BY HIRSUTELLA-THOMPSONII

A toxic protein, hirsutellin A, has been purified from the mite fungal pathogen, Hirsutella thompsonii, using ammonium sulphate precipitatio n, ion exchange chromatography and gel filtration on Bio-Gel P-10. The protein has been characterized as a monomer with a molecular mass of 15 kDa and an isoelectric point of 10.5. The amino acid composition an d the N-terminal sequence of hirsutellin A (34 amino acids) have been determined. From these results, the toxin appears to be distinct from other known proteins. It is not glycosylated, and does not show proteo lytic activity. The toxin is also antigenic, thermostable and not inac tivated by treatments with proteolytic enzymes. Toxicity bioassays sho wed that injection of larvae of the waxmoth, Galleria mellonella, with hirsutellin A at low dosages [1 mu g toxin (g body wt)(-1)] caused a high mortality rate. Hirsutellin A was also toxic per os to neonatal l arvae of the mosquito Aedes aegypti.