Genome:

• single stranded RNA (negative sense with ambisense capability)
• Linear or circular
• Multipartite (7kb Large segment, 4kb Small segment)
• Lack of cap or polyadenylation
• Genome itself is non-infectious

Morphology:

• helical, enveloped capsid. Pleomorphic in shape
• Envelope contains glycoprotein peplomers from plasma membrane budding
• 110-300nm diameter
• Virion contains nonfunctional ribosomes acquired from  host cells, giving characteristic "sandy" EM appearance.
• Two circular nucleocapsids give EM appearance comparable to strings of beads.

Encoded viral proteins:

• (N) nucleoprotein
• (L, NS1, and NS2) RNA polymerase
• (G1, G2) Glycoproteins
• (Z) Zinc-binding protein
• Protein Kinase
• poly(U) and poly (A) polymerases

Replication:

• Occurs in cytoplasm, but requires presence of intact nucleus (reasons unknown)
• Genetic reassortment occurs during replication
• Viruses bud from the plasma membrane
• Major processes in replication
  1. Transcription of minus sense (3') half of ambisense L segment to form RNA polymerase (L) mRNA.
  2. Transcription of minus sense (3') half of ambisense S segment by virion transcriptase to form nucleoprotein (N) mRNA.
  3. Translation of nucleoprotein and transcriptase required prior to viral genome replication.
  4. Transcription of glycoprotein (GPC) and zinc-binding (Z) protein mRNA.
  5. Cleavage of major glycoprotein into subunits.
  6. Budding of virion from the plasma membrane.