Cellular and Humoral Immune Profiles After Hepatitis E Vaccination and Infection

Hepatitis E virus (HEV) causes significant morbidity and mortality globally, particularly affecting vulnerable populations such as pregnant women. HEV239 (Hecolin^®), a recombinant vaccine containing the immunodominant protruding (E2) domain of the HEV capsid protein, has demonstrated effectiveness, yet detailed human cellular immune responses remain understudied. This study characterized humoral and cellular immune responses following vaccination with HEV239 or natural HEV infection in healthy Bangladeshi women aged 16-39 years. Using dual IFNγ and IL-4 ELISpot assays, we found robust, predominantly Th1-mediated cellular responses at 30 days after the third vaccine dose, comparable to responses during acute infection. Longitudinal antibody assessments confirmed sustained antibody production, primarily against the E2 domain of genotypes 1 and 3, persisting up to two years post-vaccination. Despite limitations related to sample size and assay sensitivity, our findings underscore the immunogenic potential of HEV239 and support a broader use in HEV-endemic regions.