Evidence of hepatitis E virus exposure among seronegative healthy residents of an endemic area.
OBJECTIVE
Hepatitis E virus (HEV) infection is endemic in the Indian subcontinent. Detection of serum anti-HEV IgG has traditionally been used to determine prior exposure to this virus. We studied HEV-specific recall immune responses in healthy subjects with and without detectable anti-HEV IgG.


METHODS
Memory B and T cells specific for HEV recombinant proteins pORF2 and pORF3 were estimated among healthy subjects residing in an HEV-endemic region using enzyme-linked immunospot (ELISPOT) assays.


RESULTS
Anti-HEV IgG-negative and anti-HEV IgG-positive healthy subjects had a similar median (range) number of IgG-secreting memory B cells specific for HEV pORF2 [percent of total IgG-producing cells: 0.39 (0-13.63) vs. 0.83 (0-12.78)] and HEV pORF3 [0.33 (0.05-12.35) vs. 1.01 (0.08-9.48)], and of IFN-γ-secreting memory T cells specific for HEV pORF2 [per one million PBMCs: 16 (0-220) vs. 36.5 (0-474)] and HEV pORF3 [166 (0-957) vs. 70.5 (0-533)]. Eight healthy volunteers residing in the USA and studied as controls lacked detectable T cells specific for HEV pORF2.


CONCLUSIONS
ELISPOT assays may detect evidence of prior HEV infection in persons residing in areas endemic for this infection and lacking detectable anti-HEV IgG. Seroepidemiological studies that use the serum anti-HEV IgG test may underestimate the frequency of exposure to HEV.
Department of Immunology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India.
Mohammad Mushtaq
MM
Husain
Ratika
R
Srivastava
Rama
R
Akondy
Rakesh
R
Aggarwal
Shahid
S
Jameel
Sita
S
Naik
D000328:Adult; D000956:Antigens, Viral / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology; D019353:Endemic Diseases; D058501:Enzyme-Linked Immunospot Assay; D006508:Hepatitis Antibodies / Q000097:blood*; D016751:Hepatitis E / Q000453:epidemiology* / Q000276:immunology*; D016752:Hepatitis E virus / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D007156:Immunologic Memory; D007371:Interferon-gamma / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology; D014481:United States / Q000453:epidemiology; D014764:Viral Proteins / Q000276:immunology
D000956:Antigens, Viral; D006508:Hepatitis Antibodies; D007074:Immunoglobulin G; D014764:Viral Proteins; D007371:Interferon-gamma