Since NSs can self-associate and form filamentous inclusion bodies in infected cells [65, 77] , we hypothesized that co-expression of nonfunctional NSs with the C-terminal self-association domain in cells infected with RVFV allows incorporation of such nonfunctional NSs into the NSs filament, and attenuates a part of NSs functions. However, our results were not as expected; 1) most of truncated NSs localized at cytoplasm, 2) all of truncated NSs did Our results suggest truncation of NSs causes mis-folding and/or mis-localization of protein, which might abolish the ability to interact with authentic MP-12 NSs through the C-terminus selfassociation domain. Unexpectedly, only the co-expression of NSs lacking C-terminus self-association domain (NSD249-265) slightly inhibited PKR degradation by MP-12 NSs. The NSD249-265 could accumulate both in cytoplasm and nucleus, which is consistent with previous study [65] . We speculate that NSD249-265 could compete with host factors required for PKR degradation with intact NSs. In the meantime, co-expression of NSD249-265 NSs did not result in a significant decrease of RVFV replication when compared to CAT RNA transfection control. Therefore, the co-expression of NSs fragments in infected cells might not be an effective strategy to inhibit RVFV replication in vivo.