No abstract

The fusion loop (FL), a 51-residue segment of the dengue virus (DENV) envelope (E) protein, has been shown to bind antibodies that neutralize DENV infection in cell culture. Vaccination with this loop could raise broadly neutralizing antibodies and avoid antibody dependent enhancement in second serotype infections associated with whole virus vaccination. We propose a new DENV vaccine in which FL has been genetically fused to a well-known and highly immunogenic carrier, the human papillomavirus (HPV) L1 protein (L1). Chimeric L1-FL was expressed in human cell culture, but expression levels of virus-like particles (VLP) were initially low. Expression levels were improved after adding a bridging disulfide bond at the base of the loop, and were further improved by transfecting cells with a mixture of 9 parts chimera to 1 part wild-type L1 expression vectors. VLPs formed from the chimeric construct were purified using ultracentrifugation and were shown to form hollow particles of the expected size using transmission electron microscopy. The improvements in expression are discussed in the context of a theoretical pathway for folding and assembly of VLPs.