A comparative study of five periodic human strains of Brugia malayi, originating from India, China, Korea, Malaysia and Indonesia, is given. This morphological analysis is based on males; the "standard" characters (oesophagus, papillae, spicules...) appear identical. On the contrary, the cuticular ornamentation of the posterior region--which is composed of the area rugosa and of a system of bosses and constitutes a secondary non-skid copulatory apparatus--differs following the geographical origin of the strain. A key is given, based on this character. 1(2) At 800-1,200 micron from the tip of tail, numerous cuticular bosses present on the right side of the body (fig. 2 and 8 B). 2(1) At 800-1,200 micron from the tip of tail, cuticular bosses absent or scarce on the right side of the body (fig. 8 D). 3(4) At 1,800-1,200 micron from the tip of tail (fig. 4), scarce and slightly projecting cuticular bosses on the dorsal side of the body contrasting with well projecting lateral cuticular bosses (fig. 9 E and F). Anterior extremity of the area rugosa made by a few stripes of tiny bosses linked transversally (fig. 9 A). 4(3) At 1,800-2,200 micron, numerous cuticular bosses on the dorsal side of the body (figs. 5, 6 and 7). Anterior extremity of the area rugosa made by the stripes of longitudinal rods (fig. 9C). 5(6) Oblong transversally stretched cuticular bosses on the dorsal and left sides of the body, anteriorly to the area rugosa (fig. 5); big oblong bosses on the left side (fig. 9 B). Transversal wrinkles and stripes of rods absent on the dorsal side of the body. 6(5) Round cuticular bosses on the dorsal and left sides of the body anteriorly to the area rugosa (figs. 6 and 7): no big oblong bosses on the left side. Transversal wrinkles or stripes of rods present on the dorsal side of the body (fig. 9 D). Nomenclaturally, such differences could be used in defining different taxa, but it could be useful to perform "blind determination" (material without labelling), to study conveniently the morphology of microfilariae (often an excellent indication for speciation in that group of Nematodes) and, evenly, to proceed to parallel studies on isoenzymes. However, whatever could be the taxonomical conclusion, the differences observed in Brugia malayi originating from different regions appear to the sufficient to consider the existence of four distinct diseases.
Two out of six monoclonals (McAbs) produced against subperiodic Brugia malayi infective larva (L3) antigens impaired B. malayi L3 motility independently of human buffy coat cells. Scanning electron microscopy studies showed damage to L3 surface and loss of regular cuticular annulations. The two McAbs (BML 1a and BM1 8b) did not affect B. malayi microfilaria (mf). They were IFAT-positive with B. malayi adult and L3 antigens; other McAbs which did not affect mf or L3 motility were IFAT-negative. All six McAbs did not promote cellular adherence of normal human buffy coat cells to mf or L3.