Diversity of Caenorhabditis Noda-Like Viruses
Three RNA viruses related to nodaviruses are known to naturally infect the nematodes Caenorhabditis elegans and C. briggsae. Frézal et al. (e01170-19) discovered a fourth virus in this group and reported on the ecology and genetic diversity of this viral clade. Two viral species may infect the same animal and even the same cell, but genetic exchanges were detected only between variants of a given viral species. A phenotypic assay was developed to assess the competitive abilities of two viruses in different host genotypes. These findings provide a potential method to study phenotypic evolution in both host and virus.
Coinfection of C. briggsae intestinal cells by Santeuil and Le Blanc viruses.
Murine Leukemia Virus Exploits Innate Immune Response To Promote Infection
Coevolution has helped viruses find unique ways to establish infection in susceptible hosts. Pi et al. (e00930-19) found that the Friend murine leukemia virus exploits the innate immune response designed for protection of the host to promote virus infection and spread. These findings support the need to understand the double-edged nature of host-pathogen interactions for intervention strategies.
Proposed mechanism for murine leukemia virus infection of target cells.
RNA Viruses and Liquid-Liquid Phase Separation
Cytoplasmic inclusion bodies are associated with negative-strand RNA virus replication, but their formation and regulation are not well understood. Zhou et al. (e00948-19) found that measles virus inclusion body formation is mediated by liquid-liquid phase separation (LLPS), a process known to drive the biogenesis of membraneless cellular organelles. Phosphorylation of the viral phosphoprotein and dynein-mediated transport were shown to regulate inclusion body growth. These findings, along with other recent reports, suggest that LLPS is used by some Mononegavirales as a common mechanism to assemble replication factories and may provide insight into novel antiviral strategies.
Time-lapse microscopy showing fusion and relaxation of two inclusion bodies in measles virus nucleoprotein/phosphoprotein-cotransfected HeLa cells using WDR5-EGFP as the marker.
Human Cytomegalovirus pUL37x1 Is Important for Remodeling Host Lipid Metabolism
Human cytomegalovirus (HCMV) infection remodels lipid synthesis and thus alters the host lipidome. Xi et al. (e00843-19) used high-resolution mass spectrometry lipidomic approaches to discover that HCMV protein UL37x1 is important for enhancing lipid metabolism, including fatty acid elongation, following HCMV infection. High levels of phospholipids containing long-chain fatty tails are produced by cells infected with HCMV when pUL37x1 is expressed. Furthermore, pUL37x1 enhances the HCMV-induced expression of host proteins involved in lipid metabolism. These findings suggest that pUL37x1 is an important viral factor for generating a host lipid environment that supports HCMV replication.
Heat map of phospholipid levels following HCMV infection with wild type (WT) or UL37x1-null viruses.
Vector Proteins Interact with Tomato Spotted Wilt Virus GN
Orthotospoviruses are transmitted in nature exclusively by thrips vectors in a propagative manner. The viral attachment protein (GN) protruding from the envelope of tomato spotted wilt virus (TSWV) plays a role in binding to the larval thrip’s midgut. Badillo-Vargas et al. (e00699-19) discovered two TSWV-interacting proteins, endocuticle structural glycoprotein (endoCP-GN) and cyclophilin, of Frankliniella occidentalis that robustly bind GN in vitro. Additionally, these proteins exhibit midgut and salivary gland expression and colocalize with GN in insect cells. This work opens the door for devising novel means to disrupt transmission of orthotospoviruses to crops.
In situ detection of endoCP-GN (green) in first-instar larvae of Frankliniella occidentalis.
- Copyright © 2019 American Society for Microbiology.
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- Diversity of Caenorhabditis Noda-Like Viruses
- Murine Leukemia Virus Exploits Innate Immune Response To Promote Infection
- RNA Viruses and Liquid-Liquid Phase Separation
- Human Cytomegalovirus pUL37x1 Is Important for Remodeling Host Lipid Metabolism
- Vector Proteins Interact with Tomato Spotted Wilt Virus GN
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