Antigen specific T cell responses and cytokine production in healthy subjects following a recombinant hepatitis E vaccine 3545

Abstract Description Hepatitis E virus (HEV) is a major cause of acute hepatitis in adults and has a particularly high mortality in pregnant women. HEV vaccines are known to induce protective antibodies; however, cellular immune responses following these have not been studied. We therefore evaluated T cell responses to a recombinant HEV capsid protein vaccine candidate. Healthy adults (100; 61 males, mean age 34.9±9.6 years) were randomized 3:1 to receive three intramuscular doses of a HEV ORF2-based vaccine (30 μg/dose; n = 76) or a hepatitis-B vaccine (n = 24) at 0, 1 and 6 months. Eight subjects were lost to follow-up. Antigen-induced T cell proliferation was measured using Ki67 expression at flow cytometry. In addition, TNF-α, IL-6, IFN-γ, IL-10, IL-2 and IL-4 were measured using ELISA in culture supernatants from the proliferation assay. The vaccinees showed a significant increase in antigen-specific CD3 T-cell proliferation from baseline to 7 months (0.55±0.49 vs 3.00±3.59). The increase was more pronounced in CD4 T cells (1.37±4.48 vs 4.59±6.01) than in CD8 T cells (0.57±0.65 vs 1.09±1.06). By comparison, the controls showed only a minor increase in proliferation of CD3 T cells (0.54±0.31 vs 1.80±2.52). Among the cytokines, significant increase at 7 months was observed only in TNF-α (78.53±134.1 vs 234.9±301.7) and IL-6 (228.2±263.8 vs 314.2±281.9) in the test group. In conclusion, administration of the HEV vaccine induced good antigen-specific T cell responses in the vaccinated individuals. Funding Sources Supported by BIRAC, Government of India Topic Categories Vaccines and Immunotherapy (VAC)