Grouper Interferon-Induced Transmembrane Protein 1 Inhibits Iridovirus and Nodavirus Replication by Regulating Virus Entry and Host Lipid Metabolism

Abstract

Interferon-induced transmembrane proteins (IFITMs) are novel viral restriction factors which inhibit numerous virus infections by impeding viral entry into target cells. To investigate the roles of IFITMs during fish virus infection, we cloned and characterized an IFITM1 homolog from orange spotted grouper (Epinephelus coioides) (EcIFITM1) in this study. EcIFITM1 encodes a 131-amino-acid polypeptide, which shares 64 and 43% identity with Seriola dumerili and Homo sapiens, respectively. The multiple sequence alignment showed that EcIFITM1 contained five domains, including NTD (aa 1–45), IMD (aa 46–67), CIL (aa 68–93), TMD (aa 94–119), and CTD (aa 120–131). In vitro, the level of EcIFITM1 mRNA expression was significantly up-regulated in response to Singapore grouper iridovirus (SGIV), or red-spotted grouper nervous necrosis virus (RGNNV) infection. EcIFITM1 encoded a cytoplasmic protein, which was partly colocalized with early endosomes, late endosomes, and lysosomes. The ectopic expression of EcIFITM1 significantly inhibited the replication of SGIV or RGNNV, which was demonstrated by the reduced virus production, as well as the levels of viral gene transcription and protein expression. In contrast, knockdown of EcIFITM1 using small interfering RNAs (siRNAs) promoted the replication of both viruses. Notably, EcIFITM1 exerted its antiviral activity in the step of viral entry into the host cells. Furthermore, the results of non-targeted lipometabolomics showed that EcIFITM1 overexpression induced lipid metabolism remodeling in vitro. All of the detected ceramides were significantly increased following EcIFITM1 overexpression, suggesting that EcIFITM1 may suppress SGIV entry by regulating the level of ceramide in the lysosomal system. In addition, EcIFITM1 overexpression positively regulated both interferon-related molecules and ceramide synthesis-related genes. Taken together, our results demonstrated that EcIFITM1 exerted a bi-functional role, including immune regulation and lipid metabolism in response to fish virus infections.

Differential Transcriptomics Analysis of IPEC-J2 Cells Single or Coinfected With Porcine Epidemic Diarrhea Virus and Transmissible Gastroenteritis Virus

“…IFITMs can inhibit the feline foamy virus at the late step of viral replication (42). Meanwhile, IFITM1 also exerts antiviral activity by regulating host lipid metabolism (43). We previously found that IFITM3 inhibited vaccinia virus and thrombocytopenia syndrome virus (SFTSV) infection (44,45).…”

Integrated multi-omics analysis reveals liver metabolic reprogramming by fish iridovirus and antiviral function of alpha-linolenic acid

“…Iridoviral diseases continue to pose a substantial threat to the global aquaculture industry due to their high mortality rates and lack of effective therapeutics. Our previous studies on the transcriptomic profiles of SGIV-infected spleen tissue and the metabolic profiles of SGIV-infected spleen cells provided important clues into SGIV-host interactions ( Guo et al, 2022 ; Huang et al, 2011b ; Ni et al, 2021 ), and identified numerous genes involved in innate immunity, cell death, and metabolism that influence SGIV infection ( Huang et al, 2015 ; Li et al, 2019 ; Zhang et al, 2021 ; Zheng et al, 2022 ). To date, however, the molecular events and associations at the gene, protein, and metabolite levels in vivo have not been systemically investigated.…”

“…Accumulating evidence has demonstrated that metabolites can exert proviral or antiviral effects in different stages of infection, including viral entry, replication, and release ( Alketbi et al, 2021 ; Zhang et al, 2021 ). For instance, LA can bind to PEDV NSP5 and attenuate AKT phosphorylation of the PI3K pathway to inhibit PEDV replication and release ( Yang et al, 2023 ).…”

“…Transcriptomic analysis of grouper spleen (GS) cells indicated that SGIV infection disrupts poly (I:C) stimulation-induced interferon (IFN) immune and inflammatory signaling pathways ( Wang et al, 2023 ), while lipidomic analysis showed that SGIV infection disturbs glycerophospholipid (GP) homeostasis and alters fatty acyl (FA) content ( Ni et al, 2021 ). These omics data have facilitated the identification of many genes involved in immune response, cell apoptosis, cell autophagy, and metabolism, clarifying their roles in SGIV infection ( Huang et al, 2015 ; Li et al, 2019 ; Zhang et al, 2020 , 2021 ; Zheng et al, 2022 ). However, no studies have yet illustrated the molecular events involved in SGIV infection at the systemic level or identified viable antiviral targets for the prevention and control of SGIV.…”

Positive Regulation of the Antiviral Activity of Interferon-Induced Transmembrane Protein 3 by S-Palmitoylation

“…In recent years, small interfering RNA ( 15 ) and overexpression-based screens ( 25 ) have confirmed that IFITM1, IFITM2, and IFITM3 possess broad-spectrum antiviral effects. It has been reported that IFITM proteins, when expressed in target cells, significantly inhibit more than ten families of viruses including Alphaviridae (Semliki Forest virus, Sindbis virus) ( 26 ), Arteriviridae (Porcine reproductive and respiratory syndrome virus), Asfarviridae (African swine fever virus) ( 27 , 28 ), Bunyaviridae (Rift valley fever virus, La Crosse virus, Andes virus, Hantaan virus) ( 29 – 32 ), Caliciviridae (Mouse norovirus) ( 33 ), Coronaviridae (SARS coronavirus) ( 22 , 30 , 34 , 35 ), Filoviridae (Marburg virus, Ebola virus) ( 22 , 36 , 37 ), Flaviviridae (Dengue virus, West Nile virus, Yellow fever virus, Zika virus, Omsk hemorrhagic fever virus, Hepatitis C virus, Classical swine Fever Virus, Japanese encephalitis virus and tick-borne encephalitis virus) ( 23 , 30 , 31 , 38 – 44 ), Iridoviridae (Singapore grouper iridovirus and frog iridovirus) ( 45 – 48 ), Nodaviridae(red spotted grouper nervous necrosis virus) ( 45 , 46 ), Orthomyxoviridae (Influenza A virus) ( 49 , 50 ), Paramyxoviridae (Respiratory Syncytial Virus) ( 51 – 54 ), Poxviridae (Vaccina virus) ( 55 ) Reoviridae (Reovirus) ( 56 ), Retroviridae (HIV-1 and Jaagsiekte sheep retrovirus) ( 24 , 30 , 57 , 58 ), Rhabdviridae (Vesicular stomatitis virus) ( 57 , 59 , 60 ), Phenuiviridae (Severe fever with thrombocytopenia syndrome virus) ( 33 ).…”