Investigating the interaction between dengue viral envelope proteins and host receptor molecules

Abstract

Infection of dengue remains to this date a major socio-economic and public health challenge for large parts of the world, especially low- and middle- income countries in the tropics and sub-tropics. Despite the prevalence of the associated neglected tropical diseases, progress on preventing outbreaks or fighting infection remain elusive. A major barrier towards the development of effective pharmaceuticals for dengue infection is the gap in knowledge with regards to the interaction mechanism employed by the dengue virion with its receptors and attachment factor. Particularly, prohibitins and glycosaminoglycans have been identified as playing a major role in the infection process via interactions with dengue and several other pathogens.

This study aimed to address the question of how the dengue virion initiates endocytosis via binding of attachment factors and receptor proteins, and to provide insights into the molecular mechanisms underlying viral attachment to host biomolecules. Using different avenues of research, several aspects of the dengue virion’s interaction with host factors were addressed. Recombinant prohibitin variants generated from human and Chaetomium thermophilum did not result in refolded, stable prohibitin complex in solution, hampering further structural analysis. Via biochemical analysis, prohibitin was identified as a 35kDa protein in mosquitos whereas a 120kDa prohibitin species was identified in mosquito cell lines, indicating extensive post-translational modifications. A truncation mutant corresponding to domain three of the dengue viral envelope protein (EDIII) was successfully generated and characterised as a well-folded and stable protein in solution, which enabled structural characterisation and interaction studies with glycosaminoglycans. A pH-dependent structural relaxation could be observed for this protein, which is consistent with reports of a pH-dependent structural rearrangement of the dengue virion. Interaction of EDIII with the glycosaminoglycans led to subtle structural changes and oligomerisation in a sulfation-state and pH-dependent manner.

Ultimately, GAGs were found to play an important role in viral infection alongside defined interactions with protein receptor. This interplay warrants further investigation to obtain a holistic picture of the viral attachment process and provides possible avenues for the development of transmission prevention measures.