The mammalian target of rapamycin (mTOR) is a central regulator of gene expression, translation and various metabolic processes. Multiple extracellular (growth factors) and intracellular (energy status) molecular signals as well as a variety of stressors are integrated into the mTOR pathway. Viral infection is a significant stress that can activate, reduce or even suppress the mTOR signaling pathway. Consequently, viruses have evolved a plethora of different mechanisms to attack and co-opt the mTOR pathway in order to make the host cell a hospitable environment for replication. A more comprehensive knowledge of different viral interactions may provide fruitful targets for new antiviral drugs.

Stress granules (SGs) are dynamic cytoplasmic aggregates of translationally silenced mRNAs that assemble in response to environmental stress. SGs appear to play an important role in antiviral innate immunity and many viruses have evolved to block or subvert SGs components for their own benefit. Here, we demonstrate that intracellular Ebola virus (EBOV) replication and transcription-competent virus like particles (trVLP) infection does not lead to SG assembly but leads to a blockade to Arsenite-induced SG assembly. Moreover we show that EBOV VP35 represses the assembly of canonical and non-canonical SGs induced by a variety of pharmacological stresses. This SG blockade requires, at least in part, the C-terminal domain of VP35. Furthermore, results from our co-immunoprecipitation studies indicate that VP35 interacts with multiple SG components, including G3BP1, eIF3 and eEF2 through a stress- and RNA-independent mechanism. These data suggest a novel function for EBOV VP35 in the repression of SG assembly.

BackgroundThe human immunodeficiency virus type 1 (HIV-1) Gag polyprotein is necessary and sufficient to assemble non-infectious particles. Given that HIV-1 subverts many host proteins at all stages of its life cycle, it is essential to identify these interactions as potential targets for antiretroviral therapy.FindingsThis work demonstrates the use of proximity-dependent biotin identification (BioID) of host proteins and complexes that are proximal to the N-terminal domains of the HIV-1 Gag polyprotein. Two of the hits identified in the BioID screen were validated by immunoprecipation and confirmed the interaction of DDX17 and RPS6 with HIV-1 Gag.ConclusionsOur results show that BioID is both a successful and complementary method to screen for nearby interacting proteins of HIV-1 Gag during the replicative cycle in different cell lines.Electronic supplementary materialThe online version of this article (doi:10.1186/s12985-015-0365-6) contains supplementary material, which is available to authorized users.