Genome-wide siRNA screens detect a requirement for the IKK complex in vaccinia virus infection

Friday, November 08, 2013 — Poster Session III
10:00 a.m. – 12:00 p.m.	FAES Academic Center (Upper-Level Terrace)	NIAID	MICROBIO-10

Authors

G. Sivan
S. Martin
E. Buehler
T.G. Myers
K.H. Szymczyk
B. Moss

Abstract

To systematically study the vaccinia-host interactions in HeLa cells, we have used 3 human genome-wide siRNA libraries and measured the resulting effects on vaccinia virus (VACV) replication and spread. We were surprised to find that depleting proteins annotated to NF-κB pathways attenuated VACV spread. This is inconsistent with the fact that VACV expresses proteins such as B14 and A52 that block NF-κB activation. Moreover, like others, we did not find evidence of NF-κB activation following VACV infection. However, when we treated cells with several inhibitors of the IKK complex, late gene expression was drastically reduced. In contrast, there was only a small effect on entry and early gene expression. Despite the IKK role in cell death, Caspase-8 inhibitors, as well as RIP1 inhibitors, failed to arrest VACV replication. Cells derived from different IKK-knockout mice supported our drugs and siRNA results. Moreover, these cells demonstrate a novel phenomenon in which IKK1 inhibits viral infection while IKK2 supports it, in an IKKγ independent way. The arrest in IKK2 was traced to the DNA replication step. Taken together, our results suggest that the IKK complex plays intricate role in VACV replication, independently of the NF-κB pathway.