Flavivirus NS3 and NS5 proteins interaction network: a high-throughput yeast two-hybrid screen

Abstract

Background: The genus Flavivirus encompasses more than 50 distinct species of arthropod-borne viruses, including several major human pathogens, such as West Nile virus, yellow fever virus, Japanese encephalitis virus and the four serotypes of dengue viruses (DENV type 1-4). Each year, flaviviruses cause more than 100 million infections worldwide, some of which lead to life-threatening conditions such as encephalitis or haemorrhagic fever. Among the viral proteins, NS3 and NS5 proteins constitute the major enzymatic components of the viral replication complex and are essential to the flavivirus life cycle.

Results: We report here the results of a high-throughput yeast two-hybrid screen to identify the interactions between human host proteins and the flavivirus NS3 and NS5 proteins. Using our screen results and literature curation, we performed a global analysis of the NS3 and NS5 cellular targets based on functional annotation with the Gene Ontology features. We finally created the first flavivirus NS3 and NS5 proteins interaction network and analysed the topological features of this network. Our proteome mapping screen identified 108 human proteins interacting with NS3 or NS5 proteins or both. The global analysis of the cellular targets revealed the enrichment of host proteins involved in RNA binding, transcription regulation, vesicular transport or innate immune response regulation.

Conclusions: We proposed that the selective disruption of these newly identified host/virus interactions could represent a novel and attractive therapeutic strategy in treating flavivirus infections. Our virus-host interaction map provides a basis to unravel fundamental processes about flavivirus subversion of the host replication machinery and/or immune defence strategy.

Figure 1

Human host-flavivirus protein-protein interaction network. The flavivirus NS3 and NS5 protein interactome, resulting from our Y2H screen and the literature curation, is represented here graphically. Red nodes denote viral proteins; blue nodes denotes human proteins identified by our screen; black nodes are human proteins identified in the literature; gray nodes are human proteins identified both in our screen and in the literature; red edges denote interaction between human and viral proteins; blue edges denote interaction between human proteins. Human proteins interacting with both viral proteins or with other human proteins are positioned centrally.

Figure 2

Flavivirus targeted human protein-protein interaction sub-network. The human host proteins interacting with the NS3 or the NS5 viral proteins form a connected sub-network represented here graphically. Blue nodes denote human proteins; blue edges interaction between human proteins; red strokes denote human proteins targeted by at least one protein from another virus than Flavivirus. The width of the nodes is roughly proportional to the cellular degree, i.e. the number of cellular partners in the whole human network. The largest component containing 35 proteins is represented in the middle of the network.