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Liu Z, Ma Y, Hao L. Characterization of three novel cell lines derived from the brain of spotted sea bass: Focusing on cell markers and susceptibility toward iridoviruses. FISH & SHELLFISH IMMUNOLOGY 2022; 130:175-185. [PMID: 36028055 DOI: 10.1016/j.fsi.2022.08.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 08/12/2022] [Accepted: 08/15/2022] [Indexed: 06/15/2023]
Abstract
Despite tens of cell lines originating from fish brain tissue have been constructed, little is known about the definite cell types they belong to. Whether fish cell lines derived from the brain shares similar characteristics is not well-answered yet. Here, we constructed three cell lines designated as LMB-S, LMB-M, LMB-L using brain tissue of spotted sea bass (Lateolabrax maculatus). Among them, LMB-L was identified as astroglia-like cells considering the high expression of GFAP, DCX, PTX, S100b, which are regarded as astrocyte-specific or astrocyte-associated cell markers. LMB-M exhibited smooth muscle-like features showing strong expression of LMOD1, SLAMP, M-cadherin, MGP, which are confirmed as muscle-restricted or myogenesis-involved cell markers. Although LMB-S was not definitely identified, it appeared an activation of WNT/β-catenin pathway. Besides the distinct expression profiles of cell markers, the three cell lines also presented differences in transfection efficiency and susceptibility to iridovirus infection. Relying on the established cell lines, a novel megalocytivirus, named LMIV (Lateolabrax maculatus iridovirus), was first isolated from diseased spotted sea bass. Genetic analysis of major capsid protein (MCP) and adenosine triphosphatase (ATPase) manifested that LMIV was clearly distinguishable from other representative teleost iridoviruses. Further investigations revealed that LMIV could replicate most efficiently in LMB-L cells obtaining the highest viral load (2.16 × 1010 copy/mL). By contrast, LMB-S cells gave rise to the highest viral load up to 3.86 × 108 copy/mL, when the three cell lines were infected with MRV, a newly emerged ranavirus. Moreover, LMIV infection caused lots of cells to be detached from monolayers, generating adherent and non-adherent cells. An opposite expression profiling of type I IFN pathway-related genes (JAK1, STAT1, STAT2, IRF9, Mx1) was found between adherent and non-adherent cells. Combined with the analysis of MCP gene expression, it is speculated that inhibiting type I IFN pathway in non-adherent cells allowed the facilitation of virus duplication. Taken together, the present study broadens our understanding about the diversity of cell lines derived from fish brain tissue and screening cells more susceptible to virus is not only meaningful for the development of vaccine, but also provide clues for further clarification of cell-iridovirus interactions.
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Affiliation(s)
- Zhenxing Liu
- Institute of Animal Health, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China; Key Laboratory of Livestock Disease Prevention of Guangdong Province, Guangzhou, 510640, China; Scientific Observation and Experiment Station of Veterinary Drugs and Diagnostic Techniques of Guangdong Province, Ministry of Agriculture and Rural Affairs, PR China, Guangzhou, 510640, China; Collaborative Innovation Center of GDAAS, China.
| | - Yanping Ma
- Institute of Animal Health, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China; Key Laboratory of Livestock Disease Prevention of Guangdong Province, Guangzhou, 510640, China; Scientific Observation and Experiment Station of Veterinary Drugs and Diagnostic Techniques of Guangdong Province, Ministry of Agriculture and Rural Affairs, PR China, Guangzhou, 510640, China; Collaborative Innovation Center of GDAAS, China
| | - Le Hao
- Institute of Animal Health, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China; Key Laboratory of Livestock Disease Prevention of Guangdong Province, Guangzhou, 510640, China; Scientific Observation and Experiment Station of Veterinary Drugs and Diagnostic Techniques of Guangdong Province, Ministry of Agriculture and Rural Affairs, PR China, Guangzhou, 510640, China; Collaborative Innovation Center of GDAAS, China
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Evidence for a non-fusogenic aquareovirus encoding a transmembrane protein. Arch Virol 2022; 167:571-575. [PMID: 34997319 DOI: 10.1007/s00705-021-05297-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 09/24/2021] [Indexed: 12/13/2022]
Abstract
Fusogenic aquareoviruses can induce host cell-cell fusion, forming syncytia via a fusion-associated transmembrane protein. However, there have been very few reports on non-fusogenic aquareoviruses encoding a membrane-associated protein. Previously, sequence-based analysis has indicated that grass carp reovirus strain 104 (GCRV-104), a non-fusogenic aquareovirus, encodes the proteins VP8 (nt 36-263) and VP15 (nt 400-822) in its genome segment S11. Here, we employed a liquid chromatography-tandem mass spectrometry assay to experimentally annotate small coding genes in the GCRV-104 genome and confirmed that segment S11 indeed functions as bicistronic mRNA. Notably, some additional polypeptides were identified that are encoded upstream of the VP15 open reading frame (ORF), which suggests that the virus uses a novel ORF with a non-AUG initiator codon, tentatively named VP15L (nt 274-822), which is longer than the previous putative VP15 ORF. Furthermore, a transmembrane domain was identified at the N-terminus of VP15L, but its function is unclear. Thus, the aquareovirus GCRV-104 potentially encodes a transmembrane protein, which opens a new perspective on the properties of viral proteins and the pathogenesis of this non-fusogenic reovirus.
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