Abstract:
Interleukin 1β (IL-1β) and interleukin 8 (IL-8) are two major pro-inflammatory cytokines which play a central
role in initiation of inflammatory responses against bacterial- and viral-infections. IL-1β is a member of the interleukin 1 family proteins and IL-8 is classified as a CXC-chemokine. In the current study, putative IL-1β and IL-8
counterparts were identified from a black rockfish transcriptomic database and designated as RfIL-1β and
RfIL-8. The RfIL-1β cDNA sequence consists of 1140 nucleotides with a 759 bp open reading frame (ORF) which
encodes a 252 amino acid (aa) protein, whereas the RfIL-8 cDNA sequence (898 bp) harbors a 300 bp ORF
encoding a 99 aa protein. Furthermore, the RfIL-1β aa sequence contains an IL-1 super family-like domain and
an N-terminal IL-1 super family propeptide, while the amino acid sequence of RfIL-8 consists of a typical
chemokine-CXC domain. Analysis of sequenced BAC clones containing RfIL-1β and RfIL-8 showed each gene to
contain 4 exons interrupted by 3 introns. Pairwise comparison and phylogeny analysis of these cytokine sequences clearly revealed their closer relationship with other corresponding members of teleosts compared to
birds and mammals. Constitutive differences in RfIL-1β and RfIL-8 mRNA expression were detected in a tissuespecific manner with the highest expression of each mRNA in spleen tissue. Two immune challenge experiments
were conducted with Streptococcus iniae and polyinosinic:polycytidylic acid (poly I:C; a viral double stranded
RNA mimic), and transcripts were quantified in spleen and peripheral blood cells. Significantly increased
RfIL-1β and RfIL8 transcript levels were detected with almost similar profile patterns, further suggesting a
putative involvement of these pro-inflammatory cytokines in the rockfish immunity
