Ariana Cosic, Institute of Virology/University of Zurich

Ariana Cosic (1), Melissa Lee (1), Kurt Tobler (1), Claudio Aguilar (1), Cornel Fraefel (1), Catherine Eichwald (1) Affiliation: (1)Institute of Virology, University of Zurich, Zurich, Switzerland.

Virus Replication: Entry, Exit and Everything in Between

Rotavirus (RV) is classified into nine species A-D and F-J, with RV species A (RVA) being the most extensively studied. Non-RVA species infect adult humans, various mammals, and birds; however, the lack of research tools has hindered the characterization of their life cycle. In RVA, replication and assembly occur in cytosolic inclusions termed viroplasms. We recently identified viroplasm-like structures (VLS) composed of NSP5 and NSP2, designated as VLS(NSP2)i, in non-RVA. In this context, globular VLS(NSP2)i are formed in RV species A, B, D, F, G, and I, but not in RV species C, H, and J. Additionally, in RVA, VLS can also be formed through co-expression of NSP5 with VP2, referred VLS(VP2)i. Here, we report VLS(VP2)i formation in all non-RVA species except RVB, with notable VLS formation in RVH and RVJ. Moreover, NSP2 RVH or RVJ are recruited into VLS(VP2)i. The NSP5 tail in non-RVA is required for association with VP2 and forming VLS(VP2)i. Mutation of conserved VP2-L141 in RVA to alanine disrupts viroplasm formation, impairing RV replication. Equivalent residues within the same predicted VP2 region disrupt VLS formation across non-RVA. We also observed interspecies VLS formation, particularly between closely related RVA and RVC, RVH and RVJ, and RVD and RVF. Interestingly, substituting the N-terminal region of VP2 RVB with that of the closely related VP2 RVG restores its ability to form VLS with NSP5 from either RVB or RVG. Elucidating the formation of viroplasms is essential for developing strategies to halt infection across RV species A to J.