title: Simultaneous detection of immunoglobulin A (IgA) and IgM antibodies against hepatitis E virus (HEV) Is highly specific for diagnosis of acute HEV infection.
abstract: Serum samples collected from 68 patients (age, mean +/- the standard deviation [SD], 56.3 +/- 12.8 years) at admission who were subsequently molecularly diagnosed as having hepatitis E and from 2,781 individuals who were assumed not to have been recently infected with hepatitis E virus (HEV; negative controls; 52.9 +/- 18.9 years), were tested for immunoglobulin M (IgM) and IgA classes of antibodies to HEV (anti-HEV) by in-house solid-phase enzyme immunoassay with recombinant open reading frame 2 protein expressed in the pupae of silkworm as the antigen probe. The 68 patients with hepatitis E had both anti-HEV IgM and anti-HEV IgA. Among the 2,781 controls, 16 (0.6%) had anti-HEV IgM alone and 4 (0.1%) had anti-HEV IgA alone: these IgA/IgM anti-HEV-positive individuals were not only negative for HEV RNA but lack IgG anti-HEV antibody as well (at least in most of the cases). Periodic serum samples obtained from 15 patients with hepatitis E were tested for HEV RNA, anti-HEV IgM, and anti-HEV IgA. Although HEV RNA was detectable in the serum until 7 to 40 (21.4 +/- 9.7) days after disease onset, both IgM and IgA anti-HEV antibodies were detectable until 37, 55, or 62 days after disease onset in three patients and up through the end of the observation period (50 to 144 days) in 12 patients. These results indicate that detection of anti-HEV IgA alone or along with anti-HEV IgM is useful for serological diagnosis of hepatitis E with increased specificity and longer duration of positivity than that by RNA detection.
authors.affiliation: Division of Virology, Department of Infection and Immunity, Jichi Medical School, 3311-1 Yakushiji, Minamikawachi-Machi, Tochigi-Ken 329-0498, Japan.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Takahashi
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Kusakai
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Mizuo
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Suzuki
authors.forename: Kuniko
authors.initials: K
authors.lastname: Fujimura
authors.forename: Kazuo
authors.initials: K
authors.lastname: Masuko
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Sugai
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Aikawa
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Nishizawa
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Okamoto
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006508:Hepatitis Antibodies / Q000097:blood*; D016751:Hepatitis E / Q000175:diagnosis* / Q000821:virology; D016752:Hepatitis E virus / Q000276:immunology*; D006801:Humans; D007124:Immunoenzyme Techniques; D007070:Immunoglobulin A / Q000097:blood*; D007075:Immunoglobulin M / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012367:RNA, Viral / Q000097:blood; D012680:Sensitivity and Specificity; D013045:Species Specificity
chemical_list: D006508:Hepatitis Antibodies; D007070:Immunoglobulin A; D007075:Immunoglobulin M; D012367:RNA, Viral