Carbohydrate-recognition domains on the surface of phytophagous nematodes

Human red blood cells (HRBC) adhered to preparasitic second-stage juveniles (J2) of Heterodera avenue, Heterodera schachtii, Meloidogyne javanica, Pratylenchus mediterranean, Rotylenchulus reniformis, and Tylenchulus semipenetrans over the entire nematode body. Binding was conspicuously confined to the head and tail of Longidorus cohni, Xiphinema brevicolle, and Xiphinema index. Binding was Ca²⁺ and Mg²⁺ dependent. In contrast, HRBC did not adhere to Anguina tritici, Aphelenchoides subtenius, Ditylenchus dipsaci, M. javanica females, and Panagrellas redivivus, even in the presence of these cations. Incubation of M. javanica J2 with fucose, glucose, N-acetylglucosamine, mannose, or trypsin decreased the intensity of subsequent HRBC binding, while galactose and N-acelylgalactosamine increased binding intensity. HRBC binding was diminished when nematodes were pretreated with trypsin and eliminated when pretreatments with detergents removed the surface coat. HRBC adhered to nylon fibers coated with surface coat extracted from M. javanica J2; binding was Ca²⁺ and Mg²⁺ dependent and diminished when the nylon fibers were coated with bovine serum albumin or preincubated with fucose and mannose. These results demonstrate that HRBC adhesion involves carbohydrate moieties of HRBC and corresponding carbohydrate- recognition domains (CRD) distributed in the nematode surface coat. To our knowledge this is the first report of a surface CRD in the phylum Nematoda.