heparitin-sulfate and Severe-Dengue

Dengue virus (DENV) causes fever and severe haemorrhagic symptoms in humans. The DEN2 16681 strain, derived from a dengue haemorrhagic fever patient, has been widely used in studies related to DENV pathogenesis, such as mouse and non-human primate haemorrhagic models and human vascular endothelial-cell permeability. To clarify the entry mechanism of the 16681 strain, we characterized a novel cell receptor for this strain. Our two major findings were as follows: firstly, the SDC2 membrane protein was an effective DEN2 16681 receptor in a cloned K562 cell line. Secondly, a heparan sulfate (HS) glycochain (of four glycochains in SDC2) is the specific binding site of DENV and seems to be involved in tissue-culture adaptation. Our findings present an entry mechanism that could be implicated for DENV adaptation and HS-mediated DENV infection.

Topics: Animals; Chlorocebus aethiops; Dengue Virus; Disease Susceptibility; Gene Expression; Gene Silencing; Heparitin Sulfate; Humans; K562 Cells; Receptors, Virus; Severe Dengue; Syndecan-2; Vero Cells; Virus Attachment; Virus Internalization

The four serotypes of dengue virus (DENV1 to DENV4) cause extensive morbidity and mortality. A major obstacle to studying disease pathogenesis and developing therapies has been the lack of a small-animal model. We previously reported isolation of a DENV2 strain, obtained by passaging a clinical isolate between mosquito cells and mice, that caused severe DENV disease in mice and contained multiple mutations, including many in domain II of the envelope (E) protein. Here, we describe a recombinant virus, differing from the non-mouse-passaged virus by two mutations in the E protein, that induces vascular leakage and tumor necrosis factor alpha (TNF-alpha)-mediated lethality, while the non-mouse-passaged virus causes paralysis. This recombinant virus has a weaker affinity for heparan sulfate, resulting in an increased serum half-life, higher systemic viral loads, and high levels of TNF-alpha in the serum of infected mice. These results exemplify the role of the E protein in modulating virion clearance and connect the effect of clearance on the systemic viral loads responsible for severe disease manifestations.

Topics: Animals; Dengue Virus; Heparitin Sulfate; Mice; Mutation; Serotyping; Severe Dengue; Severity of Illness Index; Specific Pathogen-Free Organisms; Tumor Necrosis Factor-alpha; Viral Load; Viral Proteins

he mechanism underlying the transient vascular leak syndrome of dengue hemorrhagic fever (DHF) is unknown. We aimed to determine whether molecular size and charge selectivity, which help restrict plasma proteins within the intravascular space, are altered in patients with DHF and whether a disturbance of the anionic glycosaminoglycan (GAG) layer on the luminal endothelial surface contributes to disease pathogenesis.. We measured serial plasma levels and fractional clearances of proteins with different size and charge characteristics in 48 children with dengue shock syndrome (DSS) and urinary excretion profiles of heparan sulfate, chondroitin-4-sulfate, and chondroitin-6-sulfate in affected children and healthy control subjects.. Compared with convalescent values, acute plasma concentrations of all proteins were reduced, with increased fractional clearances. Smaller proteins were more affected than larger molecules. Albumin, which is normally protected from leakage by its strong negative charge, demonstrated a clearance pattern similar to that of transferrin, a neutral molecule of similar size. Urinary heparan sulfate excretion was significantly increased in children with DSS.. The endothelial size-dependent sieving mechanism for plasma proteins is at least partially retained, whereas selective restriction based on negative charge is impaired. The increased heparan sulfate excretion suggests a role for GAGs in the pathogenesis of the vascular leak.

Topics: Adolescent; Child; Child, Preschool; Chondroitin Sulfates; Dengue Virus; Female; Heparitin Sulfate; Humans; Immunoglobulin G; Male; Serum Albumin; Severe Dengue; Time Factors; Transferrin