viruses Review A Look into Bunyavirales Genomes: Functions of Non-Structural (NS) Proteins Shanna S. Leventhal, Drew Wilson, Heinz Feldmann and David W. Hawman * Laboratory of Virology, Rocky Mountain Laboratories, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA;
[email protected] (S.S.L.);
[email protected] (D.W.);
[email protected] (H.F.) * Correspondence:
[email protected]; Tel.: +1-406-802-6120 Abstract: In 2016, the Bunyavirales order was established by the International Committee on Taxon- omy of Viruses (ICTV) to incorporate the increasing number of related viruses across 13 viral families. While diverse, four of the families (Peribunyaviridae, Nairoviridae, Hantaviridae, and Phenuiviridae) contain known human pathogens and share a similar tri-segmented, negative-sense RNA genomic organization. In addition to the nucleoprotein and envelope glycoproteins encoded by the small and medium segments, respectively, many of the viruses in these families also encode for non-structural (NS) NSs and NSm proteins. The NSs of Phenuiviridae is the most extensively studied as a host interferon antagonist, functioning through a variety of mechanisms seen throughout the other three families. In addition, functions impacting cellular apoptosis, chromatin organization, and transcrip- tional activities, to name a few, are possessed by NSs across the families. Peribunyaviridae, Nairoviridae, and Phenuiviridae also encode an NSm, although less extensively studied than NSs, that has roles in antagonizing immune responses, promoting viral assembly and infectivity, and even maintenance of infection in host mosquito vectors. Overall, the similar and divergent roles of NS proteins of these Citation: Leventhal, S.S.; Wilson, D.; human pathogenic Bunyavirales are of particular interest in understanding disease progression, viral Feldmann, H.; Hawman, D.W.