The ELISA-based detection of anti-Opisthorchis viverriniIgG and IgG₄in samples of human urine and serum from an endemic area of north–eastern Thailand

Abstract

The levels of correlation between the number of Opisthorchis viverrini eggs excreted in the faeces and levels of anti-Opisthorchis IgG and IgG(4) in the serum and urine (as indicated by absorbances in ELISA) have recently been evaluated in north-eastern Thailand. The 225 subjects investigated in detail, all of whom came from an endemic village in Chaiyaphum province, were selected on the basis of the numbers of O. viverrini eggs that they were excreting. ELISA based on a crude antigen extract of the trematode were then used to determine the levels of specific IgG and IgG(4) in serum and urine samples. Compared with the egg-negative, the villagers who were found to be egg-positive for O. viverrini had significantly higher levels of specific IgG in their urine and serum and significantly higher levels of specific IgG(4) in their serum. The serum levels of specific IgG and IgG(4) and the urine levels of specific IgG all correlated with the numbers of O. viverrini eggs/g faeces [with correlation coefficients (r) of 0.251, 0.121 and 0.142, respectively]. Although the serum levels of IgG were positively correlated with the urine levels of IgG (r=0.098), there was no significant relationship between the serum and urine levels of specific IgG(4) (r=0.051). When the 225 subjects investigated in the ELISA were divided according to whether they had no detectable Opisthorchis eggs in their faeces (N=57), or 1-100 (N=154), 101-1000 (N=5), 1001-1500 (N=5) or >1501 (N=4) eggs/g faeces, the serum and urine levels of specific IgG and the serum (but not urine) levels of specific IgG4 were also found to correlate significantly with the infection-intensity categories (with r-values of 0.550, 0.146 and 0.578, respectively). When the results of the faecal examinations were treated as the 'gold standard', the ELISA for the detection of (Opisthorchis-specific) serum IgG, serum IgG(4), urine IgG and urine IgG(4) had sensitivities of 99.2%, 23.1%, 43.0% and 45.9% and specificities of 93.0%, 29.6%, 45.9% and 67.2%, respectively. Although the study was limited by the small number of subjects with intense infections, it appears worth investigating urine samples for subclasses of specific IgG other than IgG(4).

Microproteinuria during Opisthorchis viverrini Infection: A Biomarker for Advanced Renal and Hepatobiliary Pathologies from Chronic Opisthorchiasis

“…Individuals and animals infected with this food-borne trematode show high serum/plasma levels of the classic antibodies associated with helminth infections such as IgG, IgG1, IgG4 and IgE to crude OV antigen extracts. As such, it has been hypothesized that circulating antibodies to OV antigens may “leak” from the plasma into the urine at levels proportionate to the intensity of OV infection [14], [16]. However, as seen in these other studies [14], [16], we found that urine IgG to OV antigen is a poor method for diagnosing OV infection and an even poorer method for predicting the intensity of OV infection (Tables 3 and 4).…”

“…Previous studies have attempted to show a correlation between the intensity of OV infection and levels of urine IgG to various crude OV antigen extracts [14]–[16]. Although urine can contain small quantities of ‘intact’ immunoglobulin as well as light and heavy chain fragments of immunoglobulin, the restrictive pore radius of the renal glomerular filter in a healthy human kidney would not filter macromolecules the size of intact IgG (for review see [17]).…”

“…Although urine can contain small quantities of ‘intact’ immunoglobulin as well as light and heavy chain fragments of immunoglobulin, the restrictive pore radius of the renal glomerular filter in a healthy human kidney would not filter macromolecules the size of intact IgG (for review see [17]). As such, the frequent observation of elevated levels of urine IgG to OV antigen in areas of high OV transmission [14]–[16] most likely reflects structural damage from immune complex deposition in the glomeruli as observed in the hamster model of OV infection [10], [11]. In the current manuscript, we investigated the presence of urine IgG to a crude adult OV antigen extract (OV antigen) in residents from OV endemic areas along the Chi River Basin, in Khon Kaen Thailand.…”

Validation of an Excretory/Secretory Antigen Based-Elisa for the Diagnosis of Opisthorchis felineus Infection in Humans from Low Trematode Endemic Areas

“…Studies in humans have shown a close relationship between parasite-specific IgG and intensity of O. viverrini infection [15]–[17]. Moreover in O. viverrini infections, the level of parasite-specific IgG is correlated to the severity of the clinical disease rather than to the egg counts in stools [16], [18]. Consequently, the detection of specific antibodies has been considered as a complementary tool to establish the definitive diagnosis of this infection [19]–[21].…”

Evaluation of liver fluke recombinant cathepsin B-1 protease as a serodiagnostic antigen for human opisthorchiasis

“…In past epidemiological surveys, crude extracts of O. viverrini worms – either from the tissues (somatic antigen preparations) and/or the excretory/ secretory products (ES) released by cultured flukes in vitro – have been employed as antigens for serodiagnosis [7,8]. However, preparation of fluke-derived antigens is tedious with maintenance of the O. viverrini parasite in the laboratory and samples of metacercariae to infect laboratory hamsters reliant on natural sources of infected, wild fishes, which are unpredictable and variable depending on the season [9].…”