Chemical synthesis and seroreactivity of O-(3,6-di-O-methyl-beta-D-glucopyranosyl)-(1----4)-O-(2,3-di-O-methyl- alpha-L-rhamnopyranosyl)-(1----9)-oxynonanoyl-bovine serum albumin--the leprosy-specific, natural disaccharide-octyl-neoglycoprotein.