The virion has not be observed, it is presumably enveloped.
Negative-stranded RNA linear genome, about 12 kb in size. Encodes for four proteins.
The viral RNA dependent RNA polymerase binds the encapsidated genome at the leader region, then sequentially transcribes each genes by recognizing start and stop signals flanking viral genes. mRNAs are capped and polyadenylated by the L protein during synthesis.