Faculty Opinions recommendation of Axl promotes zika virus entry and modulates the antiviral state of human sertoli cells.

ABSTRACT Zika virus (ZIKV) is unique among mosquito-borne flaviviruses in its ability to be sexually transmitted. Persistent ZIKV infection in the testes, which are immune privileged organs, long after peripheral clearance suggests involvement of immunosuppressive pathways; however, the underlying mechanisms remain undetermined. We recently demonstrated that ZIKV infects human Sertoli cells (SC), the major cell type of the seminiferous epithelium responsible for maintaining the immune privileged compartment of seminiferous tubules. Recent reports have identified the TAM (Tyro3, Axl, Mer) receptor tyrosine kinase Axl as an entry receptor and/or immune modulator for ZIKV in a cell type-specific manner. Interestingly, the seminiferous epithelium exhibits high basal expression of the Axl receptor where it is involved in clearance of apoptotic germ cells and immunosuppression. Here, we show that Axl was highly expressed in SC compared to Leydig cells (LC) that correlated with robust ZIKV infection of SC, but not LC. Further, neutralization of Axl receptor and its ligand Gas6 strongly attenuated virus entry in SC. However, inhibition of Axl kinase did not affect ZIKV entry but instead led to decreased protein levels of suppressor of cytokine signaling 1 (SOCS1) and SOCS3, increased expression of interferon-stimulated genes (ISGs), and reduced ZIKV replication. Similarly, treatment of multicellular human testicular organoids with an Axl kinase inhibitor attenuated ZIKV replication and increased ISG expression. Together, our data demonstrate that Axl promotes ZIKV entry and negatively regulates the antiviral state of SC to augment ZIKV infection of the testes and provides new insights into testis antiviral immunity and ZIKV persistence. IMPORTANCE Recent Zika virus (ZIKV) outbreaks have identified sexual transmission as a new route of disease spread not reported for other flaviviruses. ZIKV crosses the blood-testis barrier and establishes infection in seminiferous tubules, the site for spermatozoa development. Currently, there are no therapies to treat ZIKV infection, and the immune mechanisms underlying testicular persistence are unclear. We found that multiple human testicular cell types, except Leydig cells, support ZIKV infection. Axl receptor, which plays a pivotal role in maintaining the immunosuppressive milieu of the testis, is highly expressed in Sertoli cells and augments ZIKV infection by promoting virus entry and negatively regulating the antiviral state. By using testicular organoids, we further describe the antiviral role of Axl inhibition. The significance of our research lies in defining cross talk between Axl and type I interferon signaling as an essential mechanism of immune control that can inform therapeutic efforts to clear ZIKV from the testis.

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Human Sertoli cells support high levels of Zika virus replication and persistence

Scientific Reports ◽

10.1038/s41598-018-23899-x ◽

2018 ◽

Vol 8 (1) ◽

Cited By ~ 40

Author(s):

Anil Kumar ◽

Juan Jovel ◽

Joaquin Lopez-Orozco ◽

Daniel Limonta ◽

Adriana M. Airo ◽

...

Keyword(s):

Virus Replication ◽

Sertoli Cells ◽

Zika Virus

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The green tea molecule EGCG inhibits Zika virus entry

Virology ◽

10.1016/j.virol.2016.06.012 ◽

2016 ◽

Vol 496 ◽

pp. 215-218 ◽

Cited By ~ 87

Author(s):

Bruno M. Carneiro ◽

Mariana N. Batista ◽

Ana Cláudia S. Braga ◽

Maurício L. Nogueira ◽

Paula Rahal

Keyword(s):

Green Tea ◽

Zika Virus ◽

Virus Entry

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Expression Analysis Highlights AXL as a Candidate Zika Virus Entry Receptor in Neural Stem Cells

Cell Stem Cell ◽

10.1016/j.stem.2016.03.012 ◽

2016 ◽

Vol 18 (5) ◽

pp. 591-596 ◽

Cited By ~ 326

Author(s):

Tomasz J. Nowakowski ◽

Alex A. Pollen ◽

Elizabeth Di Lullo ◽

Carmen Sandoval-Espinosa ◽

Marina Bershteyn ◽

...

Keyword(s):

Stem Cells ◽

Neural Stem Cells ◽

Expression Analysis ◽

Zika Virus ◽

Virus Entry ◽

Entry Receptor

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Phosphatidylethanolamine and Phosphatidylserine Synergize To Enhance GAS6/AXL-Mediated Virus Infection and Efferocytosis

Journal of Virology ◽

10.1128/jvi.02079-20 ◽

2020 ◽

Vol 95 (2) ◽

pp. e02079-20

Author(s):

Lizhou Zhang ◽

Audrey S. Richard ◽

Cody B. Jackson ◽

Amrita Ojha ◽

Hyeryun Choe

Keyword(s):

Plasma Membrane ◽

Virus Infection ◽

Zika Virus ◽

Virus Entry ◽

Eukaryotic Cells ◽

Target Cells ◽

Apoptotic Cells ◽

Biological Processes ◽

Enveloped Viruses ◽

Outer Leaflet

ABSTRACTPhosphatidylserine (PS) receptors mediate clearance of apoptotic cells—efferocytosis—by recognizing the PS exposed on those cells. They also mediate the entry of enveloped viruses by binding PS in the virion membrane. Here, we show that phosphatidylethanolamine (PE) synergizes with PS to enhance PS receptor-mediated efferocytosis and virus entry. The presence of PE on the same surface as PS dramatically enhances recognition of PS by PS-binding proteins such as GAS6, PROS, and TIM1. Liposomes containing both PE and PS bound to GAS6 and were engulfed by AXL-expressing cells much more efficiently than those containing PS alone. Further, infection of AXL-expressing cells by infectious Zika virus or Ebola, Chikungunya, or eastern equine encephalitis pseudoviruses was inhibited with greater efficiency by the liposomes containing both PS and PE compared to a mixture of liposomes separately composed of PS and PE. These data demonstrate that simultaneous recognition of PE and PS maximizes PS receptor-mediated virus entry and efferocytosis and underscore the important contribution of PE in these major biological processes.IMPORTANCE Phosphatidylserine (PS) and phosphatidylethanolamine (PE) are usually sequestered to the inner leaflet of the plasma membrane of the healthy eukaryotic cells. During apoptosis, these phospholipids move to the cell’s outer leaflet where they are recognized by so-called PS receptors on surveilling phagocytes. Several pathogenic families of enveloped viruses hijack these PS receptors to gain entry into their target cells. Here, we show that efficiency of these processes is enhanced, namely, PE synergizes with PS to promote PS receptor-mediated virus infection and clearance of apoptotic cells. These findings deepen our understanding of how these fundamental biological processes are executed.

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Differential Zika Virus Infection of Testicular Cell Lines

Viruses ◽

10.3390/v11010042 ◽

2019 ◽

Vol 11 (1) ◽

pp. 42 ◽

Cited By ~ 9

Author(s):

Luwanika Mlera ◽

Marshall E. Bloom

Keyword(s):

Cell Lines ◽

Sertoli Cells ◽

Zika Virus ◽

Sexual Transmission ◽

Viral Persistence ◽

Cell Types ◽

Cell Type ◽

Testicular Cell ◽

Human Neuroblastoma ◽

Investigation Methods

Background: Zika virus is a mosquito-borne flavivirus responsible for recent outbreaks of epidemic proportions in Latin America. Sexual transmission of the virus has been reported in 13 countries and may be an important route of infection. Sexual transmission of ZIKV has mostly been male-to-female, and persistence of viral RNA in semen for up to 370 days has been recorded. The susceptibility to ZIKV of different testicular cell types merits investigation. Methods: We infected primary Sertoli cells, a primary testicular fibroblast Hs1.Tes, and 2 seminoma cell lines SEM-1 and TCam-2 cells with ZIKV Paraiba and the prototype ZIKV MR766 to evaluate their susceptibility and to look for viral persistence. A human neuroblastoma cell line SK-N-SH served as a control cell type. Results: Both virus strains were able to replicate in all cell lines tested, but ZIKV MR766 attained higher titers. Initiation of viral persistence by ZIKV Paraiba was observed in Sertoli, Hs1.Tes, SEM-1 and TCam-2 cells, but was of limited duration due to delayed cell death. ZIKV MR766 persisted only in Hs1.Tes and Sertoli cells, and persistence was also limited. In contrast, SK-N-SH cells were killed by both ZIKV MR766 and ZIKV Paraiba and persistence could not be established in these cells. Conclusions: ZIKV prototype strain MR766 and the clinically relevant Paraiba strain replicated in several testicular cell types. Persistence of ZIKV MR766 was only observed in Hs1.Tes and Sertoli cells, but the persistence did not last more than 3 or 4 passages, respectively. ZIKV Paraiba persisted in TCam-2, Hs1.Tes, Sertoli and SEM-1 cells for up to 5 passages, depending on cell type. TCam-2 cells appeared to clear persistent infection by ZIKV Paraiba.

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