A whole genome screen for HIV restriction factors

Li Liu,Viola Borgdorff,Cleo L Bishop,Matthias T Dittmar,Ann-Marie H Bergin,Kelly M Cheney,Hanna Dreja,Corinna Pade,David H Beach,Nidia Mm Oliveira,Áine Mcknight

doi:10.1186/1742-4690-8-94

Abstract

BackgroundUpon cellular entry retroviruses must avoid innate restriction factors produced by the host cell. For human immunodeficiency virus (HIV) human restriction factors, APOBEC3 (apolipoprotein-B-mRNA-editing-enzyme), p21 and tetherin are well characterised.ResultsTo identify intrinsic resistance factors to HIV-1 replication we screened 19,121 human genes and identified 114 factors with significant inhibition of infection. Those with a known function are involved in a broad spectrum of cellular processes including receptor signalling, vesicle trafficking, transcription, apoptosis, cross-nuclear membrane transport, meiosis, DNA damage repair, ubiquitination and RNA processing. We focused on the PAF1 complex which has been previously implicated in gene transcription, cell cycle control and mRNA surveillance. Knockdown of all members of the PAF1 family of proteins enhanced HIV-1 reverse transcription and integration of provirus. Over-expression of PAF1 in host cells renders them refractory to HIV-1. Simian Immunodeficiency Viruses and HIV-2 are also restricted in PAF1 expressing cells. PAF1 is expressed in primary monocytes, macrophages and T-lymphocytes and we demonstrate strong activity in MonoMac1, a monocyte cell line.ConclusionsWe propose that the PAF1c establishes an anti-viral state to prevent infection by incoming retroviruses. This previously unrecognised mechanism of restriction could have implications for invasion of cells by any pathogen.

Highlights

Upon cellular entry retroviruses must avoid innate restriction factors produced by the host cell
The use of small-interfering RNA screens has greatly extended our knowledge of the cellular processes hijacked by viruses for infection and the components needed by human immunodeficiency virus (HIV) to facilitate these early steps in replication [1,2,3,4]
System Setup To detect human cellular restriction factors that operate at the early stages of HIV-1 replication, we developed a single round infectious HIV pseudotype assay to small-interfering RNA (siRNA) screen HeLa-CD4 cells

Summary

Introduction

Upon cellular entry retroviruses must avoid innate restriction factors produced by the host cell. Viruses usurp normal cellular processes to complete their life cycle. The dsDNA in cells forms a pre integration complex (PIC) which includes viral proteins and interacts with numerous cell components. The PIC is transported into the nucleus for host DNA integration. The use of small-interfering RNA (siRNA) screens has greatly extended our knowledge of the cellular processes hijacked by viruses for infection and the components needed by HIV to facilitate these early steps in replication [1,2,3,4]. For example TNPO3, was identified by two screens to be a required for a replication step in the HIV life cycle [1,2]. TNPO3 was later shown to facilitate nuclear import of the PIC [5]

Methods

Results

Discussion

Conclusion