title: Virus-like particles displaying envelope domain III of dengue virus type 2 induce virus-specific antibody response in mice.
abstract: OBJECTIVE
  Currently, dengue represents one of the most significant arboviral disease worldwide, for which a vaccine is not yet available. Persistent challenges in live viral dengue vaccines have sparked a keen interest in exploring non-replicating dengue vaccines. We have examined the feasibility of using the methylotrophic yeast Pichia pastoris to develop a chimeric vaccine candidate displaying the dengue virus type-2 (DENV-2) envelope domain III (EDIII), implicated in host receptor binding and in the induction of virus-neutralizing antibodies, on the surface of non-infectious virus-like particles (VLP)-based on the Hepatitis B virus core antigen (HBcAg).
  
  
  METHODS
  We designed a fusion antigen by inserting DENV-2 EDIII into c/e1 loop of HBcAg. A codon-optimized gene encoding this fusion antigen was integrated into the genome of P. pastoris, under the control of the Alcohol Oxidase 1 promoter. The antigen was expressed by methanol induction and purified to near homogeneity by Ni(2+) affinity chromatography. The purified antigen was characterized physically and functionally to evaluate its ability to assemble into VLPs, and elicit DENV-2-specific antibodies in mice.
  
  
  RESULTS
  This fusion antigen was expressed successfully to high yields and purified to near homogeneity. Electron microscopy and competitive ELISA analyses showed that it formed VLPs in which the EDIII moiety was accessible to different EDIII-specific antibodies. These VLPs were immunogenic in mice, stimulating the production of antibodies that could specifically recognize DENV-2 and neutralize its infectivity. However, virus-neutralizing antibody titers were modest.
  
  
  CONCLUSIONS
  Our data show: (i) insertion of EDIII into the c/e1 loop of HBcAg does not compromise particle assembly; and (ii) the chimeric VLPs elicit a specific humoral response against DENV-2. The strategy of displaying dengue virus EDIII using a VLP platform will need further optimization before it may be developed into a viable alternative option.
authors.affiliation: Recombinant Gene Products Group, International Centre for Genetic Engineering & Biotechnology, Aruna Asaf Ali Marg, New Delhi, India.
authors.forename: Upasana
authors.initials: U
authors.lastname: Arora
authors.forename: Poornima
authors.initials: P
authors.lastname: Tyagi
authors.forename: Sathyamangalam
authors.initials: S
authors.lastname: Swaminathan
authors.forename: Navin
authors.initials: N
authors.lastname: Khanna
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood*; D053059:Dengue Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D003716:Dengue Virus / Q000235:genetics / Q000276:immunology*; D004337:Drug Carriers / Q000008:administration & dosage; D006514:Hepatitis B Surface Antigens / Q000235:genetics; D006515:Hepatitis B virus / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D010843:Pichia; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology; D017422:Sequence Analysis, DNA; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D058425:Vaccines, Virus-Like Particle / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D014759:Viral Envelope Proteins / Q000235:genetics / Q000276:immunology*
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D053059:Dengue Vaccines; D004337:Drug Carriers; D006514:Hepatitis B Surface Antigens; D011993:Recombinant Fusion Proteins; D014614:Vaccines, Synthetic; D058425:Vaccines, Virus-Like Particle; D014759:Viral Envelope Proteins