The transient nature of Bunyamwera orthobunyavirus NSs protein expression: effects of increased stability of NSs protein on virus replication

van Knippenberg, I.; Fragkoudis, R.; Elliott, R.M.

Abstract

The NSs proteins of bunyaviruses are the viral interferon antagonists, counteracting the host's antiviral response to infection. During high-multiplicity infection of cultured mammalian cells with Bunyamwera orthobunyavirus (BUNV), NSs is rapidly degraded after reaching peak levels of expression at 12hpi. Through the use of inhibitors this was shown to be the result of proteasomal degradation. A recombinant virus (rBUN4KR), in which all four lysine residues in NSs were replaced by arginine residues, expresses an NSs protein (NSs4KR) that is resistant to degradation, confirming that degradation is lysine-dependent. However, despite repeated attempts, no direct ubiquitylation of NSs in infected cells could be demonstrated. This suggests that degradation of NSs, although lysine-dependent, may be achieved through an indirect mechanism. Infection of cultured mammalian cells or mice indicated no disadvantage for the virus in having a non-degradable NSs protein: in fact rBUN4KR had a slight growth advantage over wtBUNV in interferon-competent cells, presumably due to the increased and prolonged presence of NSs. In cultured mosquito cells there was no difference in growth between wild-type BUNV and rBUN4KR, but surprisingly NSs4KR was not stabilised compared to the wild-type NSs protein.

Citation

van Knippenberg, I., Fragkoudis, R., & Elliott, R. (2013). The transient nature of Bunyamwera orthobunyavirus NSs protein expression: effects of increased stability of NSs protein on virus replication. PLOS ONE, 8(5), Article e64137. https://doi.org/10.1371/journal.pone.0064137

• Journal Article Type: Article
• Online Publication Date: May 8, 2013
• Publication Date: 2013
• Deposit Date: Jul 19, 2023
• Journal: PloS one
• Print ISSN: 1932-6203
• Publisher: Public Library of Science
• Peer Reviewed: Peer Reviewed
• Volume: 8
• Issue: 5
• Article Number: e64137
• DOI: https://doi.org/10.1371/journal.pone.0064137