Primary human endothelial cells support direct but not antibody‐dependent enhancement of dengue viral infection

Abstract

Microvascular plasma leakage is the hallmark of dengue hemorrhagic fever and dengue shock syndrome. The precise molecular mechanisms leading to microvascular leakage are yet to be determined, but dengue virus (DENV) infection and consequent endothelial cell death has been suggested as its major cause. However, the extent of endothelial cell permissiveness to DENV infection and the magnitude of cell death following DENV infection are controversial. To clarify this issue, we analyzed the kinetics and consequences of DENV infection of human umbilical vein endothelial cells (HUVEC) using a novel molecularly cloned DENV2-16681 virus. Viral replication was detected as early as 24 hr post-infection by RT-PCR and plaque assays. However, merely 2% of HUVEC were DENV antigen-positive even after 96 hr of infection as measured by the FACS indirect immunofluorescence assays. Unlike monocytes/macrophages, HUVEC did not support antibody dependent enhancement of dengue viral infection due to a lack of FcgammaRI and FcgammaRII. Furthermore, DENV infection did not increase HUVEC apoptosis as compared to mock-infected cells. Because in vitro only a small percentage of endothelial cells were productively infected in vitro with no significant apoptosis occurring in either infected or bystander cells, it would be important to re-examine whether direct dengue viral infection of endothelium is the major cause of the extensive vascular leakage observed in patients with dengue hemorrhagic fever and dengue shock syndrome.

Productive Dengue Virus Infection of Human Endothelial Cells Is Directed by Heparan Sulfate-Containing Proteoglycan Receptors

“…This suggests the potential for dengue virus to regulate early IFN responses of endothelial cells. Prior reports indicated that only a small fraction (Ͻ1 to 20%) of endothelial cells or endothelial-like cell lines are infected by dengue virus 1 to 2 days postinfection (1,2,14,43,65,70,77). Our findings may be the result of synchronously infecting low-passage-number primary human endothelial cells using an MOI of 6.…”

“…There are four dengue virus serotypes, and infection by one serotype predisposes individuals to more severe disease following a subsequent infection by a different dengue serotype. While the mechanisms of dengue virus pathogenesis are still being resolved, preexisting nonneutralizing antibodies to dengue virus proteins enhance infection of immune cells, increase the potential for DHF and DSS following dengue virus infection, and contribute to immune-mediated pathogenesis (1,19,34,38,61,67,74).…”

Dengue Virus neither Directly Mediates Hyperpermeability nor Enhances Tumor Necrosis Factor-^|^alpha;-Induced Permeability In Vitro

“…At a low MOI of 0.5, a relatively high percentage of ECs (approximately 35z) were infected. However, our findings are in contrast to the study of Ar áevalo et al, who reported that only a small portion (merely 2z) of ECs were infected by the same molecularly cloned DENV-2 16681 even at a high MOI of 20 (35). One possible explanation for this discrepancy is the history of viral passage.…”

Endothelial cells in dengue hemorrhagic fever

“…Interaction between viral particles and CLEC5A has been shown to induce production of proinflammatory cytokines which may play a role in dengue pathogenesis(Chen et al, 2008) Although DENV can infect many cell types in vitro including epithelial cells, endothelial cells, hepatocytes, muscle cells, dendritic cells, monocytes and mast cells, the roles of these cells in dengue pathogenesis and the cellular receptors involved in infection are not known(Arevalo et al, 2009; Basu et al, 2011; Brown et al, 2011; Huang et al, 2000; Paes et al, 2009; Salgado et al, 2010)…”

“…Endothelial-like cell lines and primary endothelial cells can be infected by DENV in vitro and produce viral progeny(Arevalo et al, 2009; Azizan et al, 2006; Basu et al, 2011; Dalrymple and Mackow, 2012) The infection process appears to involve heparan sulfate-containing proteoglycan receptors(Dalrymple and Mackow, 2011) The extent of the infection was fairly limited at early time points and neutralization of IFN-beta enhanced the in vitro infection of primary endothelial cells by DENV suggesting that type-I IFN response by endothelial cells limited viral replication and spreading of DENV in endothelial cell monolayers(Dalrymple and Mackow, 2012)…”