Identification of a 37.6 kDa membrane protein from flounder gill cells involved in binding and infection to lymphocystis disease virus

Abstract

Flounder gill (FG) cell line derived from the gill tissue of Japanese flounder (Paralichthys olivaceus) was employed as a target cell for investigating the molecules involved in lymphocystis disease virus (LCDV) binding and infection. Indirect immunofluorescence assay showed that LCDV could attach to the FG cells membrane susceptibly. By virus overlay protein binding assay (VOPBA), a 37.6kDa LCDV-binding protein was detected in FG cells' membrane. Two dimensional gel electrophoresis analysis revealed that the 37.6kDa protein was a single polypeptide with PI of 6.0. Mass spectrometric analysis showed that the 37.6kDa protein had a strong association with a coiled-coil domain-containing protein. While treated with trypsin or sodium periodate, the binding ability of the 37.6kDa protein to LCDV was inhibited, which suggested that sugar chains of the 37.6kDa glycosylated protein were involved in virus binding. Polyclonal antibodies were obtained by immunizing the rabbit with electroeluted 37.6kDa protein, which showed a dose-dependent blocking effect to the binding between LCDV and 37.6kDa protein in modified VOPBA, and also inhibited LCDV infection to FG cells in virus infection assay. These results demonstrated that the 37.6kDa trypsin-sensitive glycoprotein might be a potential receptor for LCDV infection to FG cells.