Typhimurium ( MacLennan et al., 2010) and this warrants further investigation. Despite its probable importance, little is known about the natural immune response to LPS. The capacity to purify LPS-specific antibodies would, for example, be useful in analysing V region usage. Purification of Salmonella OAg-antibodies from polyclonal sera would allow further characterisation of both the functionality and specificity of these antibodies. This would facilitate the ongoing investigation of their potential protective and blocking effects in individuals immunised with OAg-based vaccines and in HIV-infected African adults. Monoclonal and polyclonal

antibodies are conventionally purified by affinity chromatography (Cuatrecasas, 1970, Jack, 1994 and Huse et al., 2002), using the highly-specific nature of the interaction between antigen and antibody. this website The antigen is covalently attached to a solid support under conditions that retain antibody-binding capacity. Subsequently, when serum is passed over the antigen-bound column, only those molecules with specific affinity for the antigen are bound. After washing, the bound antibodies are eluted, thereby purifying them from the original sample. Although this method for recovering active antibodies is potentially selective, rapid and simple, allowing antibody purification

in a single chromatographic step, the recovery is typically low (Casey et al., 1995 and Cuatrecasas

and Anfinsen, 1971). find more Optimised conditions need to be determined to permit efficient purification of the desired antibodies without altering their native structure (Narhi et al., 1997a). Salmonella LPS consists of lipid A linked to the 3-deoxy-D-manno-octulosonic acid (KDO) terminus of the conserved core region, which in turn is linked to the serovar-specific OAg chain. The OAg chain is the immunodominant portion of the molecule and extends as a repeating Non-specific serine/threonine protein kinase polymer from the end of the core region ( Whitfield et al., 2003). In S. Typhimurium, the OAg repeat (O:4,5) consists of a trisaccharide backbone, with a branch of abequose, usually O-acetylated on C-2, which confers serogroup specificity (factor 4,5) ( Fig. 1A) ( Hellerqvicst et al., 1969). LPS detoxification is usually performed by acetic acid hydrolysis or by hydrazinolysis (Konadu et al., 1996), with the former commonly preferred as it retains the O-acetyl groups along the OAg chain. Acid hydrolysis cleaves the labile linkage between Lipid A and KDO leaving the OAg chain attached to the core region (Fig. 1A). Many approaches have been used to bind LPS or detoxified OAg from various bacteria to resins for use in affinity purification and, despite the high toxicity, CNBr-activated resin has been the most commonly employed (Stiller and Nielsen, 1983 and Rodahl and Maeland, 1984).