The cuticular proteins from free-living and parasitic stages of Haemonchus contortus--I. Isolation and partial characterization.

1. Cuticles were isolated from the adult males, adult females, the second molt (2M) sheath from the infective larvae (L3(2M)), and the parasitic third stage (L3) of the sheep parasite Haemonchus contortus by a combination of mechanical disruption and detergent treatment. 2. The 2ME soluble cuticular proteins from adult males contained 4 or 5 major protein bands with molecular weights ranging from 100 to 56 kD with the most prominent band at 56 kD. The cuticular proteins from adult females were similar to the male. 3. Cuticular proteins from the larval stages, 2M cuticle, and L3 cuticle, differed from the adults and from each other. The most prominent protein bands were observed with molecular weights on 78 and 39 kD for the L3 cuticle and 100, 91 and 46 kD for the 2M cuticle. The 2ME soluble cuticular proteins from all developmental stages were at least partially digested by bacterial collagenase. 4. The amino acid composition of cuticular proteins was similar for the L3 and 2M, but adults had lesser amounts of glycine and greater amounts of basic amino acids than the larval stages. The amount of the isolated cuticle solubilized by the 2ME treatment was greatest in adults (80%) compared to the L3 (64%) and the 2M (22%). 5. These results support a hypothesis that there are quantitative and qualitative stage specific differences in the cuticular proteins of H. contortus.