Characterization of the innate immune response to Streptococcus pneumoniae infection in zebrafish

we characterized the zebrafish innate immune response to pneumococcus through a whole-genome level transcriptome analysis. The analysis revealed the induction of genes coding for pro-inflammatory cytokines, chemokines, acute phase proteins, and antimicrobial peptides, indicating a well-conserved innate immune response to the human pathogen pneumococcus in zebrafish embryos. To gain understanding of the genetic factors associated with the increased risk for severe pneumococcal infection in humans, we carried out a medium-scale forward genetic screen in zebrafish. We identified a mutant fish line, which showed compromised defense against pneumococcus in septic larval infection model. Poor survival upon infection was associated with increased bacterial counts indicating defect in resistance. The transcriptome analysis of the mutant zebrafish embryos revealed otherwise normal innate immune response to pneumococcal infection but a deficient expression of a gene homologous for human C-reactive protein (CRP). Overall design: identification of the up- and downregulated genes in Streptococcus pneumoniae infection in zebrafish embryos