Visualizing tomato spotted wilt virus protein localization: Cross-kingdom comparisons of protein-protein interactions.

Tomato spotted wilt virus (TSWV) is an orthotospovirus that infects both plants and insect vectors. Understanding the protein localization and interactions is crucial for unraveling the infection cycle and host-virus interactions. We investigated and compared the localization of TSWV proteins. A change in localization over time was associated with the viral proteins that did not contain signal peptides and transmembrane domains such as N, NSs and NSm, however, this only occurred in the plant cells, not in the insect cells. The localization between plants and insects otherwise was consistent indicating a similar mechanism is utilized by the virus in both types of cells. We also tested the localization of the proteins during an active plant infection using free RFP as a marker to highlight the nucleus and cytoplasm. Voids in the cytoplasm were shown only during infection and N, NSs, NSm and to lesser extent, G_N and G_C, were surrounding these areas suggesting it may be a site of replication or morphogenesis. Furthermore, we tested the interactions of viral proteins using both bimolecular fluorescence complementation (BiFC) and membrane-based yeast two-hybrid (MbY2H) assays. These revealed self-interactions of NSm, N, G_N, G_C, and NSs. We also identified interactions between different TSWV proteins, indicating their roles and host interactions, such as between NSs and G_C and N and G_C which may be necessary during the replication and assembly processes respectively. This research expands our knowledge of TSWV infection and elaborates on the intricate relationships between viral proteins, cellular dynamics, and host responses.