First molecular cloning and gene expression analysis of teleost CD42 (glycoprotein Ib beta chain) GPIb-IX-V subunit from rock bream, Oplegnathus fasciatus.

CD42 is a platelet membrane glycoprotein Ib that plays a key role in haemostasis and thrombin-induced platelet activation. Here, we report the molecular cloning and sequence analysis of the CD42c gene from rock bream (Oplegnathus fasciatus). Rock bream CD42 (RbCD42c) gene expression profiles were determined after infection with Streptococcus iniae, Edwardsiella tarda and red seabream iridovirus (RSIV). The full-length RbCD42c cDNA contained an open reading frame of 624 bp encoding 207 amino acids. The deduced amino acid sequences of the leucine-rich repeat (LRR)-N terminal and LRR-C terminal were conserved between fish and mammals. RbCD42c was highly expressed in red blood cells, spleen, gill, liver and kidney of healthy rock bream. The RbCD42c gene was not significantly up- or downregulated after E. tarda exposure. However, RbCD42c gene expression was upregulated in kidney, spleen and gill after S. iniae infection. RbCD42c was upregulated in spleen, liver and gill, but downregulated in kidney 24 and 48 h after RSIV infection. These results suggest that RbCD42c has different expression patterns after infection with bacterial or viral pathogens. This gene may be directly involved in haemostasis.