Mapping and Immunological Response of Immunodominant B and T cell Epitopes of E2 Glycoprotein of Chikungunya Virus

Chikungunya virus (CHIKV) is a mosquito-borne Alphavirus and belongs to family Togaviridae. Debilitating arthralgia and myalgia are common symptoms of Chikungunya disease. This virus is sometimes fatal to humans, however there is no effective therapy available till now. In many studies envelope E2 protein of CHIKV has been exploited for diagnosis and vaccine therapy. Here we studied the immunodominancy of collinearly synthesized epitopes of E2 protein. Out of seventeen peptides, ten (E2P3, E2P5, E2P7, E2P8, E2P9, E2P10, E2P11, E2P13, E2P16 and E2P17) were proved to be major epitopes of E2 protein based on B and T cell response. When these peptides were immunized through intramuscular route encapsulated in PLGA microspheres with CpG ODN as an adjuvant, some sequences showed peak antibody levels ranging 1, 80,000 to 2, 20,000 in outbred and inbred (H-2d) strains of mice with memory response and they showed IgG2a and IgG2b subclass distribution. Depending upon their nature E2P1, E2P8, E2P10, E2P17 peptides showed high stimulation index during in vitro T cell proliferation assay. Plaque reduction neutralization test (PRNT90) assay proved immunodominance of few epitopes showing strong neutralization of Chikungunya virus. Thus ten peptides were considered as B cell epitopes. On the basis of cell mediated immune response and cytokine profile four peptides were considered as T cell epitopes. Three peptides E2P8, E2P10, E2P17showed common properties of B and T cells. These B and T cell epitopes can be assembled together in multiple antigenic peptides (MAPs) for developing effective immunogen for CHIKV.