Visualization of CombiHIVvac vaccine particles using electron microscopy

A candidate vaccine CombiHIVvac is developed; presently the clinical phase I trial has been completed successfully. CombiHIVvac combines the conserved polyepitope immunogens approaches in a novel self-adjuvanted microparticle concept. The artificial TBI (T cell and B cell immunogen) polypeptide used in the vaccine comprises epitopes from Env and Gag. The polypeptide is conjugated to dextran and mixed with DNA, which leads to formation of microparticles presenting TBI on the surface and containing the DNA inside. The DNA (pcDNA-TCI) enclosed in the microparticles codes for the TCI (T cell immunogen) polypeptide, which contains CD8+ and CD4+ epitopes from Env, Gag, Pol, and Nef conserved among HIV subtypes A, B, and C.1,2 The proposed technique enables the vaccine components to combine into particles on the principle of self-assembly (Fig. 1A).