Tick-borne flavivirus envelope protein (E protein)

The Tick-borne flavivirus envelope protein (E protein) is the major structural glycoprotein found on the surface of tick-borne flaviviruses, including Tick-borne encephalitis virus (TBEV) and Powassan virus [1]. It is responsible for two critical steps in the viral infection process: binding to host cell receptors and mediating the fusion between the viral and host cell membranes [2]. On the mature virion, the E protein is organized as 90 head-to-tail homodimers that cover the viral surface [3]. Upon entry into the host cell via endocytosis, the acidic environment of the endosome triggers a conformational change where the dimers dissociate and reassemble into trimers, exposing a fusion loop that inserts into the host membrane [4]. Because it is the primary target for neutralizing antibodies, the E protein is the basis for all currently approved tick-borne encephalitis vaccines and is a major target for the development of therapeutic monoclonal antibodies [5]. However, the high degree of structural similarity between flavivirus E proteins can lead to cross-reactive, non-neutralizing antibodies that may facilitate antibody-dependent enhancement (ADE) of infection [6].

Other names

Envelope glycoprotein EFlavivirus E proteinTBEV E proteinTick-borne encephalitis virus envelope proteinTBFV E protein

Neutralization of viral infectivity by binding to the E protein, which prevents viral attachment to host receptors or inhibits the pH-dependent conformational change required for membrane fusion [4, 5].