Antagonizes host type-I IFN signaling pathway. Interacts with host MAVS; this interaction may reduce MAVS ubiquitination. Expressed from the S segment by a leaky scanning mechanism (By similarity). The sequence shown is that of isolate Tula/Moravia/5302Ma/94 (Probable). The isolate Tula/Moravia/5302Ma/94 that contains the full length NSs survives for more consequent passages than the isolate Tula/Moravia/5302v/95, which contains a truncated NSs protein (PubMed:18190677). Belongs to the hantavirus NS-S protein family.