Reassortment

Virus

Influenza A virus

Disease

Coronavirus disease 2019 (COVID-19)

Biology

Viral evolution

Gene

RNA virus

Genetics

Medicine

H5N1 genetic structure

Orthomyxoviridae

Infectious disease (medical specialty)

Viral replication

Genome

Virology

Viral life cycle

Pathology

Annual Review of Virology

Influenza A viruses bear an eight-segmented single-stranded negative-sense RNA genome that is replicated in the nucleus. Newly synthesized viral RNA (vRNA) segments are exported from the nucleus and transported to the plasma membrane for packaging into progeny virions. Influenza viruses exploit many host proteins during these events, and this is the portion of the viral life cycle when genetic reassortment among influenza viruses occurs. Reassortment among influenza A viruses allows viruses to expand their host range, virulence, and pandemic potential. This review covers recent studies on the export of vRNAs from the nucleus and their transport through the cytoplasm, progressive assembly, and packaging into progeny virus particles. Understanding these events and the constraints on genetic reassortment has implications for assessment of the pandemic potential of newly emerged influenza viruses, for vaccine production, for determination of viral fitness, and for identification of novel therapeutic targets.

Moving On Out: Transport and Packaging of Influenza Viral RNA into Virions