Fluorescent #CCHF virus illuminates tissue #tropism patterns and identifies early mononuclear phagocytic cell targets in IFNAR-/- mice (PLOS Pathog., abstract)

[Source: PLOS Pathogens, full page: (LINK). Abstract, edited.]


Fluorescent Crimean-Congo hemorrhagic fever virus illuminates tissue tropism patterns and identifies early mononuclear phagocytic cell targets in IFNAR-/- mice

Stephen R. Welch, Jana M. Ritter, Anita K. McElroy, Jessica R. Harmon, JoAnn D. Coleman-McCray, Florine E. M. Scholte, Gary P. Kobinger, Éric Bergeron, Sherif R. Zaki, Stuart T. Nichol, Jessica R. Spengler , Christina F. Spiropoulou


Published: December 2, 2019 / DOI: https://doi.org/10.1371/journal.ppat.1008183 / This is an uncorrected proof.



Crimean-Congo hemorrhagic fever virus (CCHFV, order Bunyavirales, family Nairoviridae, genus Orthonairovirus) is the tick-borne etiological agent of Crimean-Congo hemorrhagic fever (CCHF) in humans. Animals are generally susceptible to CCHFV infection but refractory to disease. Small animal models are limited to interferon-deficient mice, that develop acute fatal disease following infection. Here, using a ZsGreen1- (ZsG) expressing reporter virus (CCHFV/ZsG), we examine tissue tropism and dissemination of virus in interferon-α/β receptor knock-out (Ifnar-/-) mice. We demonstrate that CCHFV/ZsG retains in vivo pathogenicity comparable to wild-type virus. Interestingly, despite high levels of viral RNA in all organs assessed, 2 distribution patterns of infection were observed by both fluorescence and immunohistochemistry (IHC), corresponding to the permissiveness of organ tissues. To further investigate viral dissemination and to temporally define cellular targets of CCHFV in vivo, mice were serially euthanized at different stages of disease. Flow cytometry was used to characterize CCHFV-associated alterations in hematopoietic cell populations and to classify infected cells in the blood, lymph node, spleen, and liver. ZsG signal indicated that mononuclear phagocytic cells in the lymphatic tissues were early targets of infection; in late-stage infection, overall, the highest levels of signal were detected in the liver, and ZsG was found in both antigen-presenting and lymphocyte cell populations.


Author summary

Human infection by tick-borne Crimean-Congo hemorrhagic fever virus (CCHFV) can result in severe disease with up to 30% case fatality rates. While CCHFV is known to be hepatotropic, the presence and implications of virus in other tissues are less clear. Furthermore, to date, early cellular targets of infection in a CCHFV disease model have not been investigated in detail. Here, using a recombinant reporter CCHFV expressing the fluorescent protein ZsGreen1 (ZsG; CCHFV/ZsG) in interferon-α/β receptor knock-out (Ifnar-/-) mice, which develop acute fatal disease following infection, we investigate both cellular and tissue targets of infection. Importantly, we find that CCHFV/ZsG infection demonstrated comparable pathogenicity to wild-type virus in Ifnar-/- mice. We used in situ visualization of fluorescent signal in tissues to assess viral dissemination throughout the course of infection, and found robust viral signal in reproductive tissues, previously unrecognized as sites of CCHFV infection. We also used flow cytometry to detect intracellular fluorescent signal, and identified initial target cells of CCHFV infection as macrophage and monocyte populations in lymphatic tissues. These findings support a central role of immune cells in early virus dissemination, and a need for further investigations into reproductive tract involvement in human CCHFV infection.


Citation: Welch SR, Ritter JM, McElroy AK, Harmon JR, Coleman-McCray JD, Scholte FEM, et al. (2019) Fluorescent Crimean-Congo hemorrhagic fever virus illuminates tissue tropism patterns and identifies early mononuclear phagocytic cell targets in IFNAR-/- mice. PLoS Pathog 15(12): e1008183. https://doi.org/10.1371/journal.ppat.1008183

Editor: Veronika von Messling, Federal Ministry of Education and Research, GERMANY

Received: June 4, 2019; Accepted: November 1, 2019; Published: December 2, 2019

This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

Data Availability: All relevant data are within the manuscript and its Supporting Information files.

Funding: This work was partially supported by an appointment to the Research Participation Program at the Centers for Disease Control and Prevention administered by the Oak Ridge Institute for Science and Education through an interagency agreement between the U.S. Department of Energy and CDC (S.R.W.), by a CDC foundation project funded by NIAID grant R01AI109008 (E.B.), and by CDC Emerging Infectious Disease Research Core Funds. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Keywords: CCHF; Viral pathogenesis.


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Giuseppe Michieli

I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.