Efficient formation and maintenance of humoral and CD4 T cell immunity targeting the viral capsid in acute-resolving hepatitis E infection

Csernalabics, B.; Marinescu, M. S.; Maurer, L.; Kelsch, L.; Werner, J.; Baumann, K.; Zoldan, K.; Panning, M.; Reuken, P.; Bruns, T.; Bengsch, B.; Neumann-Haefelin, C.; Hofmann, M.; Thimme, R.; Dao Thi, V. L.; Boettler, T.

doi:10.1101/2023.10.19.563038

bioRxiv · 10.1101/2023.10.19.563038

Efficient formation and maintenance of humoral and CD4 T cell immunity targeting the viral capsid in acute-resolving hepatitis E infection

Csernalabics, B.·Marinescu, M. S.·Maurer, L.·Kelsch, L.·Werner, J.·Baumann, K.·Zoldan, K.·Panning, M.·Reuken, P.·Bruns, T.·Bengsch, B.·Neumann-Haefelin, C.·Hofmann, M.·Thimme, R.·Dao Thi, V. L.·Boettler, T.

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Abstract

Background and aimsCD4 T cells shape the neutralizing antibody (nAb) response and facilitate viral clearance in various infections. Knowledge of their phenotype, specificity and dynamics in hepatitis E virus (HEV) infection is limited. HEV is enterically transmitted as a naked virus (nHEV) but acquires a host-derived quasi-envelope (eHEV) when budding from cells. While nHEV is composed of the open-reading-frame (ORF)-2-derived capsid, eHEV particles also contain ORF3-derived proteins. We aimed to longitudinally characterize the HEV-specific CD4 T cells and neutralizing antibodies that target either nHEV or eHEV particles in immunocompetent individuals with acute and resolved HEV infection. MethodsHEV-specific CD4 T cells were analyzed by intracellular cytokine staining after stimulation with in silico predicted ORF1- and ORF2-derived epitopes and overlapping peptides spanning the ORF3 region. Ex vivo multi-parametric characterization of capsid-specific CD4 T cells was performed using customized MHC class II tetramers. Total and neutralizing antibodies targeting nHEV or eHEV particles were determined. ResultsHEV-specific CD4 T cell frequencies and antibody titers are highest in individuals with acute infection and decline in a time-dependent process with an antigen hierarchy. HEV-specific CD4 T cells primarily target the ORF2-derived capsid, which correlates with the presence of nAbs targeting nHEV. In contrast, ORF3-specific CD4 T cells are hardly detectable and eHEV is less efficiently neutralized. Capsid-specific CD4 T cells undergo memory formation and stepwise contraction, accompanied by dynamic phenotypical and transcriptional changes over time. ConclusionThe viral capsid is the main target of HEV-specific CD4 T cells and antibodies in acute resolving infection, correlating with efficient neutralization of nHEV. Capsid-specific immunity rapidly emerges followed by a stepwise contraction for several years after infection. Impact and implicationsThe interplay of CD4 T cells and neutralizing antibody responses is critical in the host defense against viral infections, yet little is known about their characteristics in hepatitis E virus (HEV) infection. We conducted a longitudinal study of immunocompetent individuals with acute and resolved HEV infection to understand the characteristics of HEV-specific CD4 T cells and neutralizing antibodies targeting different viral proteins and particles. We found that HEV-specific CD4 T cells mainly target the viral capsid, leading to efficient neutralization of the naked virus (nHEV) while the quasi-envelope (eHEV) particles are less susceptible to neutralization. As individuals with pre-existing liver disease and immunocompromised individuals are at risk for fulminant or chronic courses of HEV infection, these individuals might benefit from the development of vaccination strategies which require a detailed knowledge of HEV-specific CD4 T cell and antibody immunity.

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Csernalabics, B., Marinescu, M. S., Maurer, L., Kelsch, L., Werner, J., Baumann, K., Zoldan, K., Panning, M., Reuken, P., Bruns, T., Bengsch, B., Neumann-Haefelin, C., Hofmann, M., Thimme, R., Dao Thi, V. L., Boettler, T.. 2023-10-21. Efficient formation and maintenance of humoral and CD4 T cell immunity targeting the viral capsid in acute-resolving hepatitis E infection. https://doi.org/10.1101/2023.10.19.563038

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