Pathogenesis of Singapore grouper iridovirus (SGIV) and its immune control strategies

Iridovirus is one of the most serious viral pathogens in marine and freshwater cultured fish. Up to now, iridoviruses have been isolated and identified from more than 100 fish species worldwide. Singapore grouper iridovirus (SGIV), a novel species of Ranavirus, was isolated from diseased grouper in Singapore. On the basis of establishing a virus-sensitive cell infection model, morphology, ultrastructure, replication and biochemical characterization of SGIV in grouper host cells were studied by electron microscopy and biochemical analysis. The molecular biological characterizations of SGIV, including viral genome, transcriptome, envelope proteome and viral microRNAs, were systematically analyzed by Omics analysis. The interactions between SGIV and host were investigated from many aspects, including identifying the target tissues of SGIV infection, tracking the single virus entry and transport, non-apoptosis cell death induced by SGIV infection, functions of host immune related genes in virus infection. Meanwhile, a variety of SGIV detection technologies have been developed, including antibody-based flow cytometry, microfluidic chip detection technology platform system, loop-mediated isothermal amplification (LAMP) and nucleic acid aptamer detection method. In addition, SGIV inactivated vaccine, subunit vaccine and DNA vaccine were developed. The results provide a theoretical basis for better understanding of the pathogenic mechanism of SGIV infection, and offer technical supports for the prevention and control of SGIV.