In vivo imaging of retrovirus infection reveals a role for Siglec-1/CD169 in multiple routes of transmission
- Yale University, School of Medicine, United States
- California Institute of Technology, United States
- Yale University, United States
- Yale University School of Medicine, United States
Abstract
Early events in retrovirus transmission are determined by interactions between incoming viruses and frontline cells near entry sites. Despite their importance for retroviral pathogenesis, very little is known about these events. We developed a bioluminescence imaging (BLI)-guided multiscale imaging approach to study these events in vivo. Engineered murine leukemia reporter viruses allowed us to monitor individual stages of retrovirus life cycle including virus particle flow, virus entry into cells, infection and spread for retroorbital, subcutaneous and oral routes. BLI permitted temporal tracking of orally administered retroviruses along the gastrointestinal tract as they traversed the lumen through Peyer's Patches to reach the draining mesenteric sac. Importantly, capture and acquisition of lymph-, blood- and milk-borne retroviruses spanning three routes, was promoted by a common host factor, the I-type lectin CD169, expressed on sentinel macrophages. These results highlight how retroviruses co-opt the immune surveillance function of tissue resident sentinel macrophages for establishing infection.
Data availability
Data is plotted as individual points wherever possible. We can provide Graphpad prism files that was used to plot all the graphs for each figure upon request. Raw datasets are freely available upon request. Interested parties should contact pradeep.uchil@yale.edu, walther.mothes@yale.edu , and we will place requested dataset onto an externally accessible Yale Box Server. Requestors will then be provided with a direct URL link from which they can download the files at their convenience. All the images acquired using confocal microscopy are available at Dryad doi:10.5061/dryad.hhmgqnkgw.
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In vivo imaging of retrovirus infection reveals a role for Siglec-1/CD169 in multiple routes of transmissionDryad Digital Repository, doi: 10.5061/dryad.hhmgqnkgw.
Article and author information
Author details
Funding
National Cancer Institute (R01 CA098727)
- Walther Mothes
National Institute of Allergy and Infectious Diseases (5P50AI150464-14)
- Pamela J Bjorkman
- Walther Mothes
National Institute of Allergy and Infectious Diseases (5R33AI122384-05)
- Priti Kumar
National Institute of Allergy and Infectious Diseases (5R01AI145164-03)
- Priti Kumar
National Institute of Allergy and Infectious Diseases (T32AI055403)
- Kelsey A Haugh
- Priti Kumar
- Walther Mothes
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: All experiments were approved by the Institutional Animal Care and Use Committees (IACUC) protocols 2020-10649 and Institutional Biosafety Committee of Yale University (IBSCYU). All the animals were housed under specific pathogen-free conditions in the facilities provided and supported by Yale Animal Resources Center (YARC). All IVIS imaging, blood draw and virus inoculation experiments were done under anesthesia using regulated flow of isoflurane:oxygen mix to minimize pain and discomfort to the animals. Animals were housed under specific pathogen-free conditions in the Yale Animal Resources Center (YARC) in the same room of the vivarium. Yale University is registered as a research facility with the United States Department of Agriculture, License and Registration number 16-R-0001 Registered until March 20, 2023. It also is fully accredited by the Association for Assessment and Accreditation of Laboratory Animal Care (AAALAC) AAALAC Accreditation: April 3, 2019. An Animal Welfare Assurance (#D16-0014) is on file with OLAW-NIH; effective May 1, 2019-May 31, 2023.
Copyright
© 2021, Haugh et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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In vivo imaging of retrovirus infection reveals a role for Siglec-1/CD169 in multiple routes of transmission
eLife 10:e64179.
https://doi.org/10.7554/eLife.64179
Further reading
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Glutamine synthetases (GS) are central enzymes essential for the nitrogen metabolism across all domains of life. Consequently, they have been extensively studied for more than half a century. Based on the ATP-dependent ammonium assimilation generating glutamine, GS expression and activity are strictly regulated in all organisms. In the methanogenic archaeon Methanosarcina mazei, it has been shown that the metabolite 2-oxoglutarate (2-OG) directly induces the GS activity. Besides, modulation of the activity by interaction with small proteins (GlnK1 and sP26) has been reported. Here, we show that the strong activation of M. mazei GS (GlnA1) by 2-OG is based on the 2-OG dependent dodecamer assembly of GlnA1 by using mass photometry (MP) and single particle cryo-electron microscopy (cryo-EM) analysis of purified strep-tagged GlnA1. The dodecamer assembly from dimers occurred without any detectable intermediate oligomeric state and was not affected in the presence of GlnK1. The 2.39 Å cryo-EM structure of the dodecameric complex in the presence of 12.5 mM 2-OG demonstrated that 2-OG is binding between two monomers. Thereby, 2-OG appears to induce the dodecameric assembly in a cooperative way. Furthermore, the active site is primed by an allosteric interaction cascade caused by 2-OG-binding towards an adaption of an open active state conformation. In the presence of additional glutamine, strong feedback inhibition of GS activity was observed. Since glutamine dependent disassembly of the dodecamer was excluded by MP, feedback inhibition most likely relies on the binding of glutamine to the catalytic site. Based on our findings, we propose that under nitrogen limitation the induction of M. mazei GS into a catalytically active dodecamer is not affected by GlnK1 and crucially depends on the presence of 2-OG.
