S-Layers in Bacterial Pathogenesis: The Tetragonal Paracrystalline Surface Protein Array of Aeromonas Salmonicida as a Special Example

A molecular approach to understanding the pathogenesis of : relevance to vaccine development

“…The A-layer is composed of a single species of protein of M r 50 000 known as the A-protein or VapA. This surface protein array appears to have a number of roles in pathogenesis, contributing to serum resistance (Munn et al, 1982), protecting against the action of proteases (Chu et al, 1991) and phagocytic cells (Garduñ o & Kay, 1992;Trust et al, 1983), as well as binding certain porphyrins, immunoglobulins, and a variety of extracellular matrix proteins (Doig et al, 1992;Trust & Kay, 1992;Trust et al, 1993). The gene encoding the A-layer subunits, vapA, has been cloned and sequenced (Belland & Trust, 1987;Chu et al, 1991).…”

Distribution of intravenously injected A-layer protein and lipopolysaccharide (LPS) from Aeromonas salmonicida in Atlantic salmon, Salmo salar L.

“…In salmon vaccinated against furunculosis, the A-layer protein has been detected in melanomacrophages of the head kidney and in a small population of tissue macrophages located near melanomacrophages in the spleen . As a surface molecule or even in a shed form, the A-protein may well exist in complex with other molecules, such as the high-molecular-weight LPS of A. salmoncida (Trust & Kay, 1992;Garduno et al, 1995). Hence, administration of a bacterin may result in di#erent localisation of complexes containing the A-layer protein compared to purified A-protein, and such a location might be the result of the acquired qualities of the complexes per se in contrast to the purified form of the molecules.…”

Molecular characterization of an Aeromonas salmonicida mutant with altered surface morphology and increased systemic virulence

“…A-layer appears to be multifunctional, contributing to serum resistance (Munn ef ai, 1982), protecting against the action of proteases (Chu et ai., 1991) and phagocytic cells (Trust et ai., 1983;Garduno and Kay, 1992;Garduiio et ai. 1993), and binding certain porphyrins, immunoglobulins, as well as a range of extracellular matrix proteins (reviewed in Trust and Kay, 1992;Trust, 1993). In order to form this important surface virulence component, the cell must translocate the A-protein monomers through the cytoplasmic membrane, periplasm and outer membrane to the surface of the celi.…”