Genome packaging of the Bunyavirales

The order Bunyavirales comprises nine families of enveloped, negative-strand RNA viruses. Depending on the family and genus, bunyaviruses (i.e. now referring to all members of the Bunyavirales) contain genomes consisting of two to six segments. Each genome segment is encapsidated by multiple copies of the nucleocapsid (N) protein and one or a few molecules of the viral polymerase, forming so-called ribonucleoproteins (RNPs). Incorporation of RNPs into virions is mediated by the interaction of N with the cytoplasmic tails of the structural glycoproteins. Although some selectivity exists in the packaging of RNPs into virions, which seems to be driven by the 5' and 3'-untranslated regions of the genomic RNA segments, evidence is accumulating that bunyavirus genome packaging is a stochastic process.