Immunobiology and Host Response to HEV.

Area of Science:

• Immunology
• Virology
• Hepatology

Background:

• Hepatitis E virus (HEV) typically causes self-limiting hepatitis, but can become chronic in immunocompromised individuals.
• HEV is not directly cytopathic; immune responses are key to pathogenesis and clearance.
• The C-terminal portion of ORF2 contains the major antigenic determinant and neutralization epitopes for HEV.

Purpose of the Study:

• To elucidate the roles of humoral and cellular immunity in Hepatitis E virus infection.
• To understand the immune response differences between acute and chronic HEV infection.
• To assess the diagnostic and prognostic value of immune markers in HEV infection.

Main Methods:

• Analysis of anti-HEV immunoglobulin M (IgM) and IgG antibody responses.
• Evaluation of innate and adaptive T-cell immune responses (CD4+ and CD8+ T cells) to HEV ORF2 protein.
• Comparison of immune responses in experimentally infected nonhuman primates and human patients with acute or chronic HEV.

Main Results:

• Robust anti-HEV IgM and IgG responses develop in acute infection and are critical for viral clearance.
• Potent, multispecific CD4+ and CD8+ T cell responses to ORF2 protein are observed in acute HEV.
• Weaker HEV-specific T cell responses are associated with chronic HEV infection in immunocompromised individuals.

Conclusions:

• Anti-HEV IgM is valuable for diagnosing acute hepatitis E.
• Anti-HEV IgG persistence aids in estimating infection prevalence and vaccine development.
• Both antibody and T-cell immune responses are critical for HEV clearance, with distinct patterns in acute versus chronic infection.