Avian air sac and plasma proteins that bind surface polysaccharides of Escherichia coli O2

Some serovars of Escherichia coli, mainly O2 and O78, are responsible for a ir sac and systemic infections in farm-raised turkeys (Meleagris gallopavo) and chickens (Gallus gallus). We looked in air sac surface fluid from youn g turkeys to identify proteins that bind surface polysaccharides of pathoge nic respiratory E. coli O2. Turkey air sac surface fluid was subjected to a ffinity chromatography on Toyopearl AF-Epoxy-650M, coupled with either lipo polysaccharide (LPS) or lipid-free polysaccharide (LFP) purified from an av ian pathogenic E. coli O2 isolate. A multimeric protein termed lipid-free p olysaccharide binding protein-40 (LFPBP-40) composed of six covalently asso ciated subunits of similar to 40 kDa was isolated by elution from UP by EDT A or L-rhamnose. An analogous protein in air sac fluid proteins bound to in tact E. coli O2 and eluted with L-rhamnose or N-acetylglucosamine (GlcNAc). The N-terminal amino acid sequence of LFPBP-40 DINGGGATLPQHLYLTPDV was rel ated to the N-terminus of fragment 3 of a partially characterized human pro tein possessing T cell stimulation activity in synovial membrane of rheumat oid arthritis patients. However, endogenous amino acid sequences were unrel ated to other known proteins. LFPBP-40 was immunoreactively distinct from p ulmonary collectins and ficolins. These studies demonstrate a novel avian r espiratory soluble lectin that can bind surface polysaccharides of pathogen ic E. coli responsible for respiratory disease. (C) 2001 Elsevier Science I nc. All rights reserved.