Lectin binding studies on adult filariae, intrauterine developing stages and microfilariae of Brugia malayi and Litomosoides carinii.

Sections of macrofilariae of Brugia malayi and Litomosoides carinii revealed binding of the gold-labelled lectins WGA, DBA and PNA. Specificity of binding was controlled by competitive inhibition with the respective sugars. N-acetyl-glucosamine, N-acetylgalactosamine and galactose residues seem to be present in the respective tissues. The lectins were bound preferentially to parts of the reproductive organs and to the fluid contents of their lumina. The results of the chitosan test and binding experiments with WGA-gold conjugate suggest the presence of chitin in the sheath of oocytes or zygotes. Binding of WGA could not be inhibited with 0.5 M N-acetylglucosamine, but only with 10 mM triacetyl chitotriose. In older stages, binding of WGA to the sheath could be inhibited by 0.5 M N-acetylglucosamine. In mature microfilariae, the outer surface of the sheath did not show affinity for WGA, but small amounts were bound to the inner surface. Therefore, the sheath of later developmental stages and microfilariae does not contain chitin but only N-acetylglucosamine residues. The degradation of the chitin content might enable the elongation and flexibility of the sheath of microfilariae.