Abstract: ORF049L of red sea bream iridovirus Liaoning strain(RSIV-LN09)gene coding a transmembrane protein was cloned,and the transmembrane region and B cell epitope were analyzed by bioinformatics.Then the ORF was inserted into the prokaryotic vector pET-28a,and a fusion protein with His-tag were obtained in Escherichia coli BL21(DE3)induced with IPTG.After denaturation,the recombinant protein was purified by affinity chromatography and identified as a specific band of 17 000(His-049L)in molecular weight by SDS-PAGE and Western blot assay.The findings provide the basis for the preparation of monoclonal antibody and function research of ORF049L.