We noted that the co-infection of recombinant MP-12 encoding truncated NSs with MP-12, except for NSD6-30 and NSD56-80, had resulted in dominant accumulation of truncated NSs. This effect may possibly occur at the transcription or translation level rather than post-translation level, since MP-12 NSs can also accumulate with truncated NSs when RNA transfection was used for truncated NSs expression. If a selective viral transcription of truncated NSs mRNA, or a selective translation of truncated NSs proteins could occur in co-infected cells, then a virus exhibiting these traits may be useful for post-exposure vaccination. However, new studies will be required to detail this mechanism.