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Objective: To study the subcellular localization of severe fever with thrombocytopenia syndrome virus (SFTSV) in macrophages and understand the replication and assembly mechanism of SFTSV in host cells., Methods: Using two types of human macrophage cell lines THP-1 and U937, the study analyzed the intracellular colocalization of SFTSV with Golgi apparatus and endoplasmic reticulum by immunefluorescence staining and confocal microscopy., Results: SFTSV infected macrophage cell lines THP-1 and U937. Immunofluorescence staining showed that the SFTSV nuclear protein colocalized with Golgi apparatus and closely surrounded by endoplasmic reticulum in the perinuclear region., Conclusion: The results suggested that Golgi complex and endoplasmic reticulum are probably the sites for formation and maturation of SFTSV viral particles.

Severe fever with thrombocytopenia syndrome bunyavirus (SFTSV) is a novel phlebovirus, causing a life-threatening illness associated with the symptoms of severe fever and thrombocytopenia syndrome. The sequence and structure of the genome have already been illustrated in previous study. However, the characteristics and function of the structure and non-structure proteins is still unclear. In this study, we identified the density of the purified SFTSV virions as 1.135 g/mL in sucrose solution. Using RT-PCR method, we amplified the full coding sequence of RNA dependent RNA polymerase(RdRp), glycoprotein precursor (M), glycoprotein n (Gn), glycoprotein c (Gc), nuclear protein (NP) and non structural protein (NSs) of SFTSV (strain HB29). Respectively inserted the target genes into eukaryotic expression vector pcDNA5/FRT or VR1012, the target protein in 293T cell were successfully expressed. By analyzing the SFTSV virions in SDS-PAGE and using recombinant viral proteins with SFTS patients sera in Western blotting and Immunofluorescent assay, the molecule weight of structure and non-structure proteins of SFTSV were defined. The study provides the first step to understand the molecular characteristics of SFTSV.