Lymphocystis disease virus(LCDV)is the causative agent of lymphocystis disease,which has infected more than 140 species of marine and freshwater fish belonging to 42 families worldwide and caused great economic losses.Determination of the receptor molecules on the surface of susceptible cells will contribute to the understanding of viral infection,pathogenesis and tissue tropism in hosts,which will also benefit the development of anti-viral therapeutic agents.In this paper,monoclonal antibodies(Mabs)2G11 and 3D9 against 27.8 ku receptor protein of LCDV were applied to detect LCDV receptor in the peripheral blood,leukocyte,gill,stomach,intestine,skin,liver,head-kidney,body kidney,spleen,gonad,brain and heart tissues in flounder(Paralichthys olivaceus)by indirect immunofluorescence assay and immunohistochemical experiment.Results showed that receptor-positive signals were found in cell membranes of leukocytes,gill,gastric mucosal cells,intestinal epidermal cells,epidermis,liver,connective tissue cells in the spleen surface and tubular epithelium behind the headkidney,which indicated that LCDV 27.8 ku receptor protein existed in these tissues.No receptor-positive signals were observed in the body kidney,gonad,brain,heart tissues and red blood cells ofP.olivaceus.We deduced that LCDV entered the fish’s body through binding to the receptor molecules in gill,epidermis and gastrointestinal epithelium,or entered the peripheral blood and infected the leucocyte and then transmitted to other tissues(liver,spleen,head-kidney,etc.)through blood circulation.