Variable Surface Epitopes in the Crystal Structure of Dengue Virus Type 3 Envelope Glycoprotein

Abstract

Dengue virus is an emerging global health threat. The major envelope glycoprotein, E, mediates viral attachment and entry by membrane fusion. Antibodies that bind but fail to neutralize noncognate serotypes enhance infection. We have determined the crystal structure of a soluble fragment of the envelope glycoprotein E from dengue virus type 3. The structure closely resembles those of E proteins from dengue type 2 and tick-borne encephalitis viruses. Serotype-specific neutralization escape mutants in dengue virus E proteins are all located on a surface of domain III, which has been implicated in receptor binding. While antibodies against epitopes in domain I are nonneutralizing in dengue virus, there are neutralizing antibodies that recognize serotype-conserved epitopes in domain II. The mechanism of neutralization for these antibodies is probably inhibition of membrane fusion. Our structure shows that neighboring glycans on the viral surface are spaced widely enough (at least 32 Å) that they can interact with multiple carbohydrate recognition domains on oligomeric lectins such as DC-SIGN, ensuring maximum affinity for these putative receptors.

Preparation and immunogenic properties of a recombinant West Nile subunit vaccine

“…This was shown in the crystal structure of a carboxy truncated dengue virus envelope protein which was determined using protein expressed in S2 cells [24][25][26]. Thus, the expression system is highly efficient both in terms of the quality of antigen produced as well as the quantity.…”

“…These include: (i) a "naked" DNA vaccine encoding the prM and E genes [15]; (ii) a live, attenuated dengue serotype 4-WNV chimera [16]; (iii) a live attenuated Yellow Fever-WNV chimera [17]; (iv) a recombinant envelope protein vaccine expressed in E. coli [18] and Drosophila cells [19]; (v) a live, attenuated WNV (veterinary) vaccine [20]; (vi) a formalininactivated WNV (veterinary) vaccine [21]; and a canarypox virus vectored vaccine [22]. Scientists at Hawaii Biotech have successfully used a proprietary method of expression to produce recombinant envelope proteins from flaviviruses, such as dengue serotypes 1-4, JEV, hepatitis C, and WNV [23][24][25][26]. These proteins are truncated at the C-terminus, leaving 80% of the native envelope protein (80E).…”

“…The truncation deletes the membrane anchor portion of the protein, thus allowing it to be secreted into the extracellular medium, facilitating recovery. Furthermore, the expressed proteins have been shown to be properly glycosylated and to maintain native conformation as determined by reactivity with conformationally sensitive monoclonal antibodies (Hawaii Biotech, unpublished data), and X-ray crystallography structure determination [24][25][26]. The expression system used to produce these recombinant proteins involves the construction of expression plasmids containing cDNAs which are then used to transform insect cells.…”

Mapping to completeness and transplantation of a group-specific, discontinuous, neutralizing epitope in the envelope protein of dengue virus

“…DENV1-DENV4 are enveloped RNA viruses, like all flaviviruses. The structures of the whole virus and of the envelope glycoprotein E (gpE) have been solved by electron cryomicroscopy and X-ray crystallography (Modis et al, 2003(Modis et al, , 2005Zhang et al, 2003). Ninety dimers of gpE cover the surface of the virus.…”

Papel de las células dendríticas en la infección por el virus dengue: blancos de replicación y respuesta inmune

“…Pertenece a la familia Flaviviridae y es un virus envuelto con genoma ARN monocatenario de polaridad positiva [ssRNA(+)] que codifica para tres proteínas estructurales (C, prM, E) y siete no estructurales (NS1, NS2A, NS2B, NS3, NS4A, NS4B y NS5) (Figura 1), involucradas en la replicación del ARN, el ensamblaje del virus y la modulación de la respuesta inmune de la célula hospedera [7][8][9][10] (Tabla 1). Múltiples monómeros de la proteína C encapsidan el ARN viral para formar la nucleocápside 11,12 , la que está rodeada por una bicapa lipídica de origen celular donde se encuentran ancladas las proteínas M (matriz) y E (envoltura) 13 . La proteína E es de especial importancia para el reconocimiento y unión a los receptores que median la entrada del virus a la célula blanco 4 , por endocitosis mediada por receptor; así inicia su ciclo de replicación.…”