A role for glycolipid biosynthesis in severe fever with thrombocytopenia syndrome virus entry.

A novel bunyavirus was recently found to cause severe febrile illness with high mortality in agricultural regions of China, Japan, and South Korea. This virus, named severe fever with thrombocytopenia syndrome virus (SFTSV), represents a new group within the Phlebovirus genus of the Bunyaviridae. Little is known about the viral entry requirements beyond showing dependence on dynamin and endosomal acidification. A haploid forward genetic screen was performed to identify host cell requirements for SFTSV entry. The screen identified dependence on glucosylceramide synthase (ugcg), the enzyme responsible for initiating de novo glycosphingolipid biosynthesis. Genetic and pharmacological approaches confirmed that UGCG expression and enzymatic activity were required for efficient SFTSV entry. Furthermore, inhibition of UGCG affected a post-internalization stage of SFTSV entry, leading to the accumulation of virus particles in enlarged cytoplasmic structures, suggesting impaired trafficking and/or fusion of viral and host membranes. These findings specify a role for glucosylceramide in SFTSV entry and provide a novel target for antiviral therapies.

Application of gene-editing technologies to HIV-1.

PURPOSE OF REVIEW: This review will highlight some of the recent advances in genome engineering with applications for both clinical and basic science investigations of HIV-1. RECENT FINDINGS: Over the last year, the field of HIV cure research has seen major breakthroughs with the success of the first phase I clinical trial involving gene editing of CCR5 in patient-derived CD4(+) T cells. This first human use of gene-editing technology was accomplished using zinc finger nucleases (ZFNs). Zinc finger nucleases and the advent of additional tools for genome engineering, including transcription activator-like effector nucleases (TALENS) and the clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 system, have made gene editing remarkably simple and affordable. Here we will discuss the different gene-editing technologies, the use of gene editing in HIV research over the past year, and potential applications of gene editing for both in-vitro and in-vivo studies. SUMMARY: Genome-engineering technologies have rapidly progressed over the past few years such that these systems can be easily applied in any laboratory for a variety of purposes. For HIV-1, upcoming clinical trials will determine if gene editing can provide the long-awaited functional cure. In addition, manipulation of host genomes, whether in vivo or in vitro, can facilitate development of better animal models and culture methods for studying HIV-1 transmission, pathogenesis, and virus-host interactions.

The major cellular sterol regulatory pathway is required for Andes virus infection.

The Bunyaviridae comprise a large family of RNA viruses with worldwide distribution and includes the pathogenic New World hantavirus, Andes virus (ANDV). Host factors needed for hantavirus entry remain largely enigmatic and therapeutics are unavailable. To identify cellular requirements for ANDV infection, we performed two parallel genetic screens. Analysis of a large library of insertionally mutagenized human haploid cells and a siRNA genomic screen converged on components (SREBP-2, SCAP, S1P and S2P) of the sterol regulatory pathway as critically important for infection by ANDV. The significance of this pathway was confirmed using functionally deficient cells, TALEN-mediated gene disruption, RNA interference and pharmacologic inhibition. Disruption of sterol regulatory complex function impaired ANDV internalization without affecting virus binding. Pharmacologic manipulation of cholesterol levels demonstrated that ANDV entry is sensitive to changes in cellular cholesterol and raises the possibility that clinically approved regulators of sterol synthesis may prove useful for combating ANDV infection.