Submitted to: Fish and Shellfish Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/2006
Publication Date: 1/31/2007
Citation: Klesius, P.H., Evans, J.J., Shoemaker, C.A. 2007. The macrophage chemotactic activity of Streptococcus agalactiae and Streptococcus iniae extracellular products (ECP). Fish and Shellfish Immunology. 22(5)443-450. Interpretive Summary: Little information is available on inflammation in fish infected with streptococci. Macrophages play an important role in inflammation and immunity to streptococci. This investigation demonstrated that macrophages migrate towards extracellular products of streptococci. The chemotactic response of macrophages to extracellular products excreted or secreted by streptococci in fish tissues results in inflammation and an immune response to the streptococci. This investigation demonstrated that extracellular products of Streptococcus agalactiae and S. iniae were chemotactic for fish macrophages, and thus pro-inflammatory molecules. The importance of cellular immunity responses are being recognized as well as the role of anti-streptococcal antibody in immunity and prevention of streptococcal infection of fish.
Technical Abstract: The ability of Streptococcus agalactiae and Streptococcus iniae to attract macrophages of Nile tilapia (Oreochromis niloticus) was investigated. The extracellular products (ECP) from S. agalactiae and S. iniae were tested for macrophage chemotaxis using in vitro blind well chambers. The macrophages were obtained from the peritoneal cavity 4-5 d after the intraperitoneal injection of squalene. Macrophage chemotactic and chemokinetic activities were demonstrated with both ECPs. Macrophage chemotactic activity of S. agalactiae ECP was about two times higher than that of S. iniae. The chemokinetic activity of S. agalactiae was three times higher than that of S. iniae. High-pressure liquid chromatography fractionation revealed that estimated molecular weight of the semi-purified S. agalactiae ECP was considerably smaller (290 D) than that of S. iniae (14 kD). The prominent chemotactic activities of ECP from S. agalactiae and S. iniae are likely to be involved in the proinflammatory responses of macrophages to S. agalactiae and S. iniae infections.