One-day-old leghorn chickens were used in a laboratory assay to determine the toxicity of crude extracts of the tick Argas (Persicargas) walkerae and of fractions obtained during the isolation procedure. Extracts of unfed and engorged larvae, nymphae and females were tested using this in vivo test system. Only extracts of replete A. (P.) walkerae larvae produced paralysis.
A toxic fraction was isolated from replete larval extracts by gel-permeation and ion-exchange chromatography. This fraction with a pI of 4,5 showed 2 major bands corresponding to a Mᵣ of 32 kDa and 60 kDa after SDS-polyacrylamide gel electrophoresis.
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