Abstract
Two CXC chemokines in Nile tilapia (On-CXC1 and On-CXC2) were identified at both the genomic and proteomic levels. A southern blot analysis and comparison searching in Ensembl confirmed the typical structure of the CXC chemokine genes and provided evidence for unusual mechanisms used to generate the two different CXC chemokine transcripts that have not been reported in other vertebrate species so far. The expression levels of On-CXC1 and On-CXC2 were analyzed by quantitative real-time PCR. These two mRNAs were detected in various tissues of normal Nile tilapia, especially in the spleen, heart, and head kidney, indicating a homeostatic function in immunosurveillance. A time-course experiment clearly demonstrated that these two transcripts were effectively enhanced in the head kidney, spleen and trunk kidney of Nile tilapia 6, 12 and 24 h after injection with Streptococcus agalactiae but were down-regulated in all tested tissues at 48 h, reflecting the fact that they have short half-lives during the crucial response to pathogens that is characteristic of CXC chemokine genes in other vertebrates. Functional analyses obviously exhibited that these two CXC chemokines at concentrations of 1–10 μg strongly inactivated S. agalactiae and Flavobacterium columnare and effectively induced phagocytosis of leukocytes in vitro.
Highlights
Tilapia is one of the most popular fish cultured in global aquaculture after carp and salmonid fish
The result from this study showed that On-CXC1 and On-CXC2 mRNA were rapidly up-regulated to different levels in all tested tissues during the first 6–12 h after injection with 1 × 103 and 1 × 109 CFU/mL of S. agalactiae
The results showed that both rOn-CXC1 and rOn-CXC2 have broad-spectrum antimicrobial activities acting against both Gram-positive (S. agalactiae) and -negative (F. columnare) bacteria in a dose-dependent manner
Summary
Tilapia is one of the most popular fish cultured in global aquaculture after carp and salmonid fish. Intensive production of Nile tilapia has been rapidly developed to increase their yield This practice has led to more undesirable conditions than other systems, and it is the cause of a higher number of infectious agents, including parasites, viruses and bacteria [2]. Among these pathogens, Streptococcus agalactiae (Group B Streptococcus; GBS) is a common pathogenic bacterium that is a major cause of streptococcosis in Nile tilapia in Thailand. It is important to understand the fish immune system and develop prophylactic or therapeutic strategies applicable to Nile tilapia aquaculture
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
