To assess the membrane oligosaccharide composition from selected isolates of Leptospira and determine its utility as a diagnostic antigen

Abstract

Leptospires are corkscrew-shaped bacteria, and the genus Leptospira is divided into two species with different metabolic properties: L. interrogans and L. biflexa. The classification of Leptospira is based on the expression of the surface exposed epitopes in a mosaic of the lipopolysaccharide (LPS) antigens, while the specificity of the epitopes depends on their sugar composition and orientation. Leptospiral lipopolysaccharide is clearly an antigen to which there is a significant antibody response. The LPS is composed of three covalently-linked distinct components: lipid A, which is the hydrophobic part embedded in the outer membrane; O-antigen or O-polysaccharide, which is extended from the cell surface to the external environment; and the core oligosaccharide, which links the O-antigen to the lipid A. The glycobiology of Leptospira is an unexplored area even though the polysaccharide component of the LPS has been shown to be a major antigen contributing to the specificity with other gram-negative pathogens. The serological assays that are commonly performed to detect anti-Leptospiral antibodies include the microscopic agglutination tests (MAT) and enzyme-linked immunosorbent assays (ELISA). The approved MAT assay requires the continued maintenance of the reference Leptospira serovars; therefore, ELISA is performed as an alternative to detect the antibodies. For this purpose, the LPS is the commonly used capture antigen. newlineFuture studies are required for understanding the monosaccharide component across different leptospiral serovars. The polysaccharide were also subjected for seroreactivity analysis. However, further studies are required for understanding the utility of the membrane oligosaccharide component for its diagnostic ability as well the potential to differentiate across different serovars. newline newlineKeywords- Leptospira, LPS, FT-NIR, purified polysaccharide, serovar cross-reactivity newline newline