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Kasikci, E.

Publications and source records attributed to Kasikci, E..

3 recordsLinked to original sources

Phosphatidylserine receptors are critical for lethal infection by Crimean-Congo hemorrhagic fever virus

The tick-borne Crimean-Congo hemorrhagic fever virus (CCHFV) causes severe and often fatal hemorrhagic disease for which no approved countermeasures are available. Herein, we identify the phosphatidylserine receptors (PSRs) AXL, TIM-1, and TIM-4 as critical entry host factors for CCHFV in cell lines and liver-derived primary cell cultures. Small-molecule and antibody-based PSR inhibitors greatly reduced viral infection in cell culture. Germline knockout of individual PSR genes afforded partial protection against CCHFV infection, disease, and death in a murine model of lethal viral challenge. Mice engineered to lack two PSRs were completely protected from challenge, with viremia and viral replication, pathology, and inflammation in the liver and spleen reduced to baseline. Therefore, PSRs are collectively indispensable for CCHFV infection and pathogenesis. We conclude that PSRs are not just cell entry factors but bona fide determinants of infection, dissemination, and disease by CCHFV and legitimate targets for the development of new antiviral countermeasures.

microbiology↗

Expanded protocadherin-1 usage reveals a broader hantavirus entry landscape

Mammalian hantaviruses are RNA viruses that cause hantavirus cardiopulmonary syndrome in the Americas and hemorrhagic fever with renal syndrome in Eurasia. The cellular entry mechanisms of most hantaviruses remain poorly defined. To examine entry by phylogenetically distinct hantaviruses, we generated replication-competent recombinant vesicular stomatitis viruses (rVSVs) bearing Gn/Gc proteins from Necocli, Sangassou, Thottapalayam, Kenkeme, Nova, Oxbow, and Tula viruses. All these Gn/Gc proteins except Kenkeme supported infection of primary human endothelial cells, indicating that endothelial cell entry is permissive for a broader range of hantaviruses than previously appreciated. Except for rVSV-Kenkeme, these rVSVs did not acquire additional mutations beyond pre-engineered rescue-enhancing changes during rescue and passaging. Genetic studies in human cells lacking protocadherin-1 (PCDH1) showed that Necocli, Tula, and Nova viruses use PCDH1 for efficient infection, although the Nova phenotype was weaker. These three Gn/Gc proteins bound soluble PCDH1 with different apparent avidities, and infection by the corresponding rVSVs was inhibited by soluble PCDH1; Necocli and Tula, but not Nova, were also blocked by a PCDH1-targeting monoclonal antibody. Authentic Tula virus infection was similarly reduced in PCDH1 knockout endothelial cells. Finally, the broadly reactive anti-Gn/Gc human monoclonal antibody ADI-42898 efficiently neutralized Necocli, Nova, Sangassou, and Kenkeme rVSVs but showed weak or undetectable activity against Oxbow, Tula, and Thottapalayam rVSVs. Together, these findings expand the range of hantavirus glycoproteins capable of mediating infection of human endothelial cells, broaden the phylogenetic scope of PCDH1-dependent entry, and identify receptor-targeted and viral glycoprotein-targeted strategies with differential activity. ImportanceMany newly discovered hantaviruses are known only from sequence data, leaving their ability to enter human cells and their receptor usage unresolved. Using a BSL2-compatible rVSV system, we show that glycoproteins from several divergent hantaviruses can mediate infection of primary human endothelial cells, indicating that endothelial cell entry is permissive for a broader range of hantaviruses than previously appreciated. We also show that protocadherin-1 (PCDH1), previously linked mainly to New World hantaviruses, is used by Necocli, Tula, and Nova viruses but not universally across the panel, revealing broader but heterogeneous receptor usage. An authentic Tula virus experiment supports this conclusion beyond the surrogate system. Finally, a broadly reactive anti-Gn/Gc antibody neutralizes several, but not all, of these viruses, highlighting both the promise and the limits of broadly protective countermeasures and the utility of these rVSVs for evaluating entry inhibitors.

microbiology↗

Genetic depletion studies define receptor usage by virulent hantaviruses in human endothelial cells

Hantaviruses are a large group of RNA viruses that include known epidemic threats and other agents poised for emergence. Several rodent-borne hantaviruses cause zoonoses accompanied by severe illness and death. However, assessments of zoonotic risk and the development of countermeasures alike are challenged by our limited knowledge of the molecular mechanisms of hantavirus infection, including the identities of cell entry receptors and their roles in influencing viral host range and virulence. Previous work has implicated several cell-surface molecules, most notably {beta}3- and {beta}1-containing integrin heterodimers, decay-accelerating factor (DAF), and the cadherin superfamily protein protocadherin-1 (PCDH1), in hantavirus entry in endothelial cells, the major targets of viral infection in humans. Despite the fact that {beta}3/{beta}1 integrins have been presumed to be the major hantavirus entry receptors for over two decades, rigorous genetic evidence supporting their requirement, and that of DAF as an entry cofactor, is lacking. Here, we used CRISPR/Cas9 engineering to knock out four candidate hantaviral receptors, singly and in combination, in a human endothelial cell line that recapitulates the properties of primary microvascular endothelial cells. PCDH1 loss substantially reduced entry and infection by a subset of hantaviruses endemic to the Americas. In contrast, the loss of {beta}3 integrin, {beta}1 integrin, and/or DAF had little or no effect on entry by any of a large panel of hantaviruses tested. We conclude that the major host molecules necessary for endothelial cell entry by PCDH1-independent hantaviruses remain to be discovered.

microbiology↗