Abstract: Hitherto that whether piscine CXC can interact with more immune cells and if there is any molecular evidence supports such activations are unclear. In present study, the levels of tilapia IL-8 in kidney, spleen, liver, macrophages and lymphocytes were significantly up-regulated (p<0.05) post infection or immunization with S. iniae. Notably, the dynamic variation of tIL-8 in four tilapia species with immunization but not infection of S. iniae was positively associated with their features of disease resistance. The putative tIL-8 contains a typical structure of the incomplete ELR motif (ELH). However, the piscine incomplete ELR+ CXC and the mammals or avian complete ELR+ CXC are fell into two separate evolutionary branches both are independent to the lamprey IL-8. The findings showed tIL-8 is involved in the functions of tilapia macrophages and lymphocytes and can be a reference marker for disease resistant breeding this may due to its sequence and evolutionary features showing the early jawless fish not other fishes might be the intermediate stage evolving from ELR¯ CXC to ELR+ CXC to obtain its chemotactic ability on immune cells.
C. Ming, W. Rui, L. Liping, T. Huang, H. Weiyi, L. Jian, L. Chao, L. Aiying, L. Honglin and L. Wanwen, 2013. Sequence and Evolution Differences of Oreochromis niloticus CXC Contribute to the Diversification of Cellular Immune Responses in Tilapias with Treatment of Streptococcus iniae. Journal of Animal and Veterinary Advances, 12: 303-311.