Trichostrongylus colubriformis: analysis of monoclonal antibody and lectin binding to the larval cuticle.

ABSTRACT

A monoclonal antibody (VRI 86-1) raised against third stage Trichostrongylus colubriformis preferentially bound to the excretory pore of living exsheathed larvae, with little or no binding to other sites on the parasite surface. A similar binding pattern was observed with fluorescein-labelled wheat germ agglutinin (WGA), although the anterior end of the parasite was also stained. To gain information at the molecular level regarding the parasite components at these sites, the residues recognized by WGA (i.e. N-acetylglucosamine and N-acetylneuraminic acid) were radiolabelled on the surface of living larvae. After homogenization and detergent extraction of the larvae, four dominant bands and a number of minor bands were revealed by SDS-PAGE and fluorography. None of these bands was specifically immunoprecipitated or recognized on a Western blot by VRI 86-1, suggesting that the epitope recognized by this antibody either resides on a different molecule or is destroyed or changed during the radiolabelling procedures. These results provide further evidence that the nematode cuticle is not uniform at the molecular level, and that the excretory pore contains molecules and antigens that may be unique to that site.