A pivotal role for theStreptococcus iniaeextracellular polysaccharide in triggering proinflammatory cytokines transcription and inducing death in rainbow trout

Abstract

Streptococcus iniae is a major pathogen of fish, causing considerable economic losses in Israel, the United States and the Far East. Containment of mortalities through vaccination was recently compromised due to the emergence of novel vaccine-escape strains that are distinguished from previous strains by their ability to produce large amounts of extracellular polysaccharide (EPS) that is released to the medium. In vitro and in vivo data now indicate that the EPS is a major virulence factor, capable of triggering the proinflammatory cytokine machinery and inducing mortality of fish. Streptococcus iniae EPS might therefore be considered to be responsible for sepsis and death just as lipopolysaccharide is for Gram-negative pathogens.

Molecular characterization and comparative expression analysis of two teleostean pro-inflammatory cytokines, IL-1β and IL-8, from Sebastes schlegeli

“…Similarly, comparable mRNA expressional profiles of IL-8 have also been reported in yellow croaker (Li and Yao, 2013) and Japanese sea perch (Qiu et al, 2009) upon bacterial-and/or LPS-challenges. Although Gram positive bacteria, such as S. iniae, are not capable of producing LPS, their extracellular polysaccharides (EPS) have been shown to trigger the induction of pro-inflammatory cytokines (Eyngor et al, 2010). Meanwhile, mRNA expressional response of IL-1β against nodavirus in sea bream (Poisa-Beiro et al, 2008) and IL-8 against poly I:C in large yellow croaker (Li and Yao, 2013), respectively, have been reported to have an analogous profile to those seen in our current study.…”

Interactions of Streptococcus iniae with phagocytic cell line

“…Also, was investigated the role of S. iniae extracellular polysaccharide in triggering proinflammatory cytokines transcription and inducing death in rainbow trout gonad cell line [21].…”

Innate Immune Response to Streptococcus iniae Infection in Zebrafish Larvae

“…iniae utilizes a number of identified virulence factors to evade host defense and establish disease (35)(36)(37)(38)(39)(40). In particular, the polysaccharide capsule of S. iniae is important for virulence in adult zebrafish (41)(42)(43).…”