Characterization of two grouper Epinephelusakaara cell lines: Application to studies of Singapore grouper iridovirus (SGIV) propagation and virus–host interaction

The establishment of continuous fish cell lines is essential for studying viral pathology and host–virus interactions. In the present study, two cell lines, designated as EAGS and EAGSB, were established from the spleen and swim bladder of grouper, Epinephelusakaara. Both cells multiplied well in Leibovitz's L-15 medium supplemented with 10% fetal bovine serum, at temperatures between 25 and 30 °C. Chromosome analysis revealed that modal chromosome number was 88 and 72 for EAGS and EAGSB, respectively. Both cell lines were susceptible to Singapore grouper iridovirus (SGIV), as shown by cytopathic effect (CPE) and increased viral titers. SGIV replication in EAGS and EAGSB cells was further confirmed by electron microscopy and immunofluorescence microscopy. However, both cell lines were not susceptible to soft-shelled turtle iridovirus (STIV), viral nervous necrosis virus (VNNV) and spring viremia of carp virus (SVCV). Hoechst staining showed that no apoptotic bodies were examined in SGIV infected cells, suggesting that SGIV infection induced EAGS cells death might be distinguished from typical apoptosis. Moreover, SGIV infection in EAGS altered the morphology and structure of microtubules, including rearrangement into a ring-like structure around the nucleus, and aggregations around the virus assembly sites. All these data imply that EAGS and EAGSB cells have good potential for investigation of the interactions between SGIV and host cells.