== Group I, healthy control group (n=40); Group II, confirmed amebic liver abscess (ALA) cases (n=14); and Group III, diseases other than ALA (n=276). == Table 2. significantly differ between assessments measuring total IgG and IgG1 (Exact McNemars test;p> 0.05), with a concordance of 98.2%, represented by a Cohens kappa of 0.83 (p< 0.001), indicating almost ideal agreement. == Conclusion == ELISA targeting IgG1 can provide valuable information to clinicians in differentiating ALA from other parasitic diseases, cancers, cirrhosis, and viral hepatitis. However, enzyme-conjugated anti-human total IgG is usually cheaper than anti-human IgG subclasses. Therefore, we suggest that total IgG-based ELISA is sufficient for the routine serodiagnosis of human ALA and possibly other clinical manifestations of invasive amebiasis. Keywords:Amebic liver abscess,Entamoeba histolytica, Enzyme-linked immunosorbent assay, Immunoglobulin G subclasses, Serodiagnosis == Introduction == Amebiasis, an infection caused byEntamoeba histolytica, is the second leading cause of death from protozoan infections worldwide (Stanley Jr, 2003;Lozano et al., 2012), affecting an estimated 50 million people and causing the death of 40,000100,000 people yearly (Shirley et al., 2018). The infection is frequently transmitted to humansviathe fecal-oral route, which is prevalent in areas with poor sanitation, or through oral-anal sexual contact (Tanyuksel & Petri Jr, 2003;Shirley et al., 2018). Most infected people are asymptomatic, but some develop invasive amebiasis, which is becoming more common among homosexual men and acquired immunodeficiency syndrome patients (Takeuchi et al., 1989;Huang et al., 2020). The most common extraintestinal manifestation is an amebic liver abscess (ALA), which is usually associated with significant morbidity and mortality (Alavi, 2007;Kannathasan et al., 2018;Marenga et al., 2019). Trophozoites ofE. histolyticatravel from your intestine to the liverviathe portal vein and produce hepatic inflammation followed by necrosis, leading to an abscess. ALA can be diagnosed by detecting motile trophozoites in liver pus; however, this requires a relatively invasive process and is not a sensitive diagnostic method. Polymerase chain reaction (PCR) assay, the platinum standard method, helps diagnose ALA if aspirated pus is usually available, but this technique is costly and only used in some laboratories, particularly in developed countries, where infrastructure and skillful staff are available (Zaman et al., 2000;Tanyuksel & Petri Jr, 2003;Ryan, Paparini & Oskam, 2017;Saidin, Othman & Noordin, 2019). Therefore, in practice, the diagnosis of ALA is based on clinical features, history of living in or traveling to endemic regions, imaging techniques such as ultrasound (US), computerized tomography (CT), and magnetic resonance imaging (MRI), as well as serological assessments (Wong et al., 2017), like immunofluorescence (IF) assessments (Garcia et al., 1982;Jackson, CB-839 Anderson & Simjee, 1984), indirect hemagglutination assays (IHA) (Knobloch & Mannweiler, 1983;Hung et al., 1999;Dhanalakshmi, Meenachi & Parija, 2016), enzyme immunoassays (Yang & Kennedy, 1979;Hock et al., 1989;Shetty et al., 1990;Knappik, Borner & Jelinek , 2005;Wong et al., 2017;Beyls et al., 2018), and lateral circulation immunoassays (Saidin et al., CB-839 2014;Tachibana et al., 2018;Noordin et al., 2020). The enzyme-linked immunosorbent assay (ELISA) is still the most common test in many countries for diagnosing ALA due to its high sensitivity, specificity, ease of use, and cost-effectiveness. In addition, detecting antibodies can be beneficial when fecal microscopy or antigen detection tests are ineffective for Prkwnk1 diagnosis. In endemic settings, however, significant background measurements are produced; consequently, the original protocols cut-off may need to be adjusted for each individual situation (Fotedar et al., 2007;Saidin, Othman & Noordin, 2019), particularly by including healthy volunteer samples in each area for baseline subtraction and evaluating a larger quantity of other infectious disease samples as preliminary data for describing awareness prior to clinical use. To discriminate between previous and present infections, the best specimens, like pus or serum, should be submitted to a molecular reference laboratory for identifying the infectious agent (Zaman et al., 2000;Ghelfenstein-Ferreira et al., 2020). Nowadays, in developing countries with limited resources, where PCR is not routinely conducted in the CB-839 clinical laboratory, positive antibody screening along with a patients clinical manifestations, risk history, other laboratory findings, and/or abdominal imaging are useful for CB-839 diagnosis (Fotedar et al., 2007;Saidin, Othman & Noordin, 2019). For ELISA, most of the circulatingE. histolytica-specific antibody detection tests show using immunoglobulin G (IgG) in the detection system (Yang & Kennedy, 1979;Knappik, Borner & Jelinek, 2005;Fotedar et al., 2007;Wong et al., 2017;Beyls et al., 2018;Saidin, Othman & Noordin, 2019;Watanabe et al., 2021) because invasive amebic infections.