Solid-phase enzyme-linked immunosorbent assay for hepatitis E virus IgG and IgM antibodies utilizing recombinant antigens and synthetic peptides

Souto

Mem. Inst. Oswaldo Cruz

et al. 2002

We investigated the seroprevalence of hepatitis A virus (HAV) and hepatitis E virus (HEV) infection in subjects living in the community of Manguinhos, Rio de Janeiro, Brazil, and assisted Key words: hepatitis A virus -hepatitis E virus -seroprevalence -epidemiology -Rio de Janeiro -Brazil Viral hepatitis is a public health problem worldwide. Two of the agents that cause viral hepatitis are enterically transmitted: hepatitis A virus (HAV) and hepatitis E virus (HEV).In the last years, improvements in environmental sanitation and hygienic conditions, such as piped water and sewage system, have been responsible for a decrease in the endemicity level of hepatitis A in several developing countries. In Brazil, although hepatitis A is considered an endemic disease (Pannuti et al. 1985, Abuzwaida et al. 1987, Bensabath et al. 1987, Queiroz et al. 1995, data published in recent investigations carried out in the State of Rio de Janeiro revealed a shift in the hepatitis A epidemiological pattern. Improvements in life standards of some urban populations are responsible for a decrease in antibody prevalence among children and adolescents (Vitral et al. 1998a,b).HEV infection is quite common in some geographic areas like India, Africa and Southeast Asia, where it can represent the main cause of acute hepatitis (Arankalle et al. 1995 reported in these areas (Shakhgildyan et al. 1986, CDC 1987, Belyakov et al. 1990, Zuang 1992. On the other hand, epidemiological investigations in non-endemic areas show a low, but constant presence of anti-HEV antibodies (about 1.2%) in normal human populations (Balayan et al. 1996, Psichogiou et al. 1996, Irshad 1999.In 1986, the occurrence of outbreaks of HEV infection in the Americas was recognized in Mexico (Velazquez et al. 1990). More recently, two acute cases of hepatitis E were described in Argentina (Schlauder et al. 2000). In Brazil, outbreaks of hepatitis E have never been reported, although some authors found antibodies in some population groups (Focaccia et al. 1995, Parana et al. 1997, Souto & Fontes 1998, Trinta et al. 2001.Nowadays, hepatitis A can be prevented by active immunoprophylaxis and, for a better control of infection, it is necessary to investigate its current prevalence in different areas. On the other hand, further data are needed in order to evaluate the importance of HEV infection in our country. The aim of the present study was to evaluate the prevalence of HAV and HEV infections in an area where sanitary conditions were improved over the last few years. MATERIALS AND METHODSCalculation of sample size -The minimum sample size was estimated using the formula: n = Z² P Q / d², considering as n = estimated sample size; Z = reduced variable, which value is 1,96 when alpha = 0,05; P (estimated prevalence) = probability to achieve the studied phenomenon; Q (1-P) = complement of the estimated prevalence; d (desired precision) = margin of error.

Section: Discussionsupporting

confidence: 79%

Seroepidemiological markers of enterically transmitted viral hepatitis A and E in individuals living in a community located in the North Area of Rio de Janeiro, RJ, Brazil

Souto

Mem. Inst. Oswaldo Cruz

et al. 2002

Journal of Immunological Methods

“…Additionally, HEV-RNA may be detected in the blood or stool from up to 50% of anti-HEV IgM positive cases (El-Sayed Zaki et al, 2006). However, these tests have not been as reliable as similar tests for hepatitis A virus (HAV) and hepatitis B virus (HBV) (Bryan et al, 1994;Dawson et al, 1992;Favorov et al, 1992;Goldsmith et al, 1992). Until recently, commercial tests for anti-HEV IgG have demonstrated inconsistent sensitivity and specificity.…”

Section: Introductionmentioning

confidence: 99%

“…However, a recently available commercial assay for anti-HEV IgM (HEV-IgM ELISA 3.0, MP Diagnostics, formerly Genelabs Diagnostic, Singapore) appears promising for detecting acute HEV infections (Chen et al, 2005). AntiIgM peaks up to four weeks after onset of AVH and is no longer detectable in half of the cases after three months (Arankalle et al, 1994;Bryan et al, 1994;Dawson et al, 1992). Additionally, it is not known how long anti-IgG persists because of differences in sensitivity of the EIA.…”

Section: Introductionmentioning

confidence: 99%

Characterization of hepatitis E-specific cell-mediated immune response using IFN-γ ELISPOT assay

Shata

Barrett

Shire

et al. 2007

In developing countries, hepatitis E (HEV) and hepatitis A (HAV) are the major causes of acute viral hepatitis with similar fecooral modes of transmission. In contrast to the high seroprevalence of hepatitis A infection, a low seroprevalence of HEV among children in endemic areas has been reported. These data suggest the possibility that silent HEV infection is undiagnosed by the current available methods. Many of the serological tests used for HEV diagnosis have poor specificity and are unable to differentiate among different genotypes of HEV. Moreover, the RT-PCR used for HEV isolation is only valid for a brief period during the acute stage of infection. Cell-mediated immune (CMI) responses are highly sensitive, and long lasting after sub-clinical infections as shown in HCV and HIV. Our objective was to develop a quantitative assay for cell-mediated immune (CMI) responses in HEV infection as a surrogate marker for HEV exposure in silent infection. Quantitative assessment of the CMI responses in HEV will also help us to evaluate the role of CMI in HEV morbidity. In this study, an HEV-specific interferon-gamma (IFN-γ) ELISPOT assay was optimized to analyze HEV-specific CMI responses. We used peripheral blood mononuclear cells (PBMC) and sera from experimentally infected chimpanzees and from seroconverted and control human subjects to validate the assay. The HEV-specific IFN-γ ELISPOT responses correlated strongly and significantly with anti-HEV ELISA positive/negative results (rho=0.73, p=0.02). Moreover, fine specificities of HEV-specific T cell responses could be identified using overlapping HEV ORF2 peptides.

Microbiology and Immunology

“…Recombinant antigens representing the putative structural gene sequence derived from open-reading frame (ORF) 2 and ORF3 of the HEV genome have been investigated extensively for the development of a test of recombinant-based enzymelinked immunosorbent assay (ELISA) or a Western blot assay for diagnosis of HEV infection (5,12,15). The newly developed serological diagnostic systems for HEV infection have been widely used to study the seroprevalence among different study populations of epidemic areas (3,9,12,15). In order to demonstrate the prevalence of IgG antibodies to HEV (IgG anti-HEV) in Southern Taiwan, we have done a retrospective serological analysis in healthy individuals among different study populations.…”

mentioning

confidence: 99%

Prevalence of Antibody to Hepatitis E Virus among Healthy Individuals in Southern Taiwan

Peng

Lin

Chue

et al. 1995

The seroprevalence of hepatitis E virus (HEV) among 997 healthy individuals aged 6 to 84 years, collected between July 1993 and June 1994 at Kaohsiung-Pingtung area in Southern Taiwan was studied. Of the study populations of vegetable farmers, elementary school children, volunteer blood donors and college students, the prevalence of IgG anti-HEY ranged from 6.4% to 8.8%. In suburban elemantary school children of Mang-Chou Village at Pingtung-Hsien, the seroprevalence rate (9.6%) was significantly higher than the positive rate (1.5%) found in rural aboriginal elementary school of San-Min Village at Kaohsiung-Hsien. IgG anti-HEY antibodies were widely distributed among all age groups, with a significantly higher percentage (13.1 %) in the age group of 46-55 years old.