Empty virus-like particle-based enzyme-linked immunosorbent assay for antibodies to hepatitis E virus

Abstract

Hepatitis E, an enterically transmitted non-A, non-B hepatitis, is a serious viral infection that occasionally causes large epidemics in developing countries. In developed countries, the disease only appears sporadically due to the transmission routes, and it is considered to be less important. The hepatitis E virus (HEV) cannot grow in cultured cells and no reliable assay system has ever been developed. In addition, the present diagnostic are not perfect, and actual rates of HEV infection may be underestimated. Highly purified empty virus-like particles (VLPs) of HEV have been produced by the use of a recombinant baculovirus vector in insect cells. Using these VLPs as an antigen, an enzyme-linked immunosorbent assay (ELISA) for antibodies to HEV was developed. A panel of 164 sera that were randomized and coded, and sera collected periodically from three patients with hepatitis E were used for the evaluation. The sensitivity of the assay was shown to be equal to or better than that obtained in previous research that used the same serum panel. The ELISA demonstrated that the serum IgM level of the patients was highest at the onset of the clinical illness and then rapidly decreased. In contrast, a high level of circulating IgG antibody titers lasted for more than 4 years. In Japan, a non-endemic country, the prevalence of the IgG class antibody to HEV in healthy individuals was found to range from 1.9% to 14.1%, depending on the geographical area. Only one out of 900 (0.1%) serum samples was IgM-positive. The IgM class antibody to HEV was detected in 10.8% of non-A, non-B, and non-C acute hepatitis patients in northeast China, whereas none of the patients in Korea had the IgM antibody. The ELISA utilizing the VLPs is sensitive and specific in its detection of the IgM and IgG antibodies to HEV. The ELISA is therefore useful for diagnosing HEV infection and for seroepidemiological study of hepatitis E.

Serological Evidence for Hepatitis E Virus Infection in Laboratory Monkeys and Pigs in Animal Facilities in Japan

“…This assay was capable of detecting anti-HEV antibodies in human sera with high sensitivity and specificity [17]. The HEV specificity of the ELISA in monkey sera was confirmed by western blot assay in this survey.…”

A Patient with Clinical Features of Acute Hepatitis E Viral Infection and Autoimmune Hepatitis

“…In industrialized countries, although anti-HEV has been detected in 4 to 36% of healthy individuals (Tam et al 1991;Hsieh et al 1999;Pina et al 2000;Meng et al 2002), sporadic cases of hepatitis E which were not associated with traveling to endemic area have rarely been reported (Schlauder et al 1998;Erker et al 1999;Hsieh et al 1999;Schlauder et al 1999;Zanetti et al 1999;Li et al 2000;Wu et al 2000;Takahashi et al 2002a). …”

Prevalence of Hepatitis E Virus (HEV) Infection in Wild Boars (Sus scrofa leucomystax) and Pigs in Gunma Prefecture, Japan

“…Serologic analysis: Anti-HEV IgG was measured by ELISA as previously described with some modifications [4]. The antigen used in the ELISA was HEV-like particles composed of a truncated open reading frame 2 (ORF2) protein of genotype I HEV expressed by a recombinant baculovirus in insect cells and was suspended with 0.5 M carbonate buffer (pH 12.5) at a concentration of 1 µg/ml [3].…”