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Background: The sensitivity of parasitological and molecular methods is unsatisfactory for the diagnosis of strongyloidiasis, and serological techniques are remaining as the most effective diagnostic approach. The present study aimed to design and produce a chimeric recombinant antigen from Strongyloides stercoralis immunoreactive antigen (SsIR) and Ss1a antigens, using immune-informatics approaches, and evaluated its diagnostic performance in an ELISA system for the diagnosis of human strongyloidiasis. Methodology/Principal findings: The coding sequences for SsIR and Ss1a were selected from GenBank and were gene-optimized. Using bioinformatics analysis, the regions with the highest immunogenicity that did not overlap with other parasite antigens were selected. The chimeric recombinant antigen SsIR- Ss1a, was constructed. The solubility and physicochemical properties of the designed construct were analyzed and its tertiary structures were built and evaluated. The construct was expressed into the pET-23a (+) expression vector and the optimized DNA sequences of SsIR-Ss1a (873 bp) were cloned into competent E. coli DH5α cells. Diagnostic performances of the produced recombinant antigen, along with a commercial kit were evaluated in an indirect ELISA system, using a panel of sera from strongyloidiasis patients and controls. The physicochemical and bioinformatics evaluations revealed that the designed chimeric construct is soluble, has a molecular with of 35 KDa, and is antigenic. Western blotting confirmed the immunoreactivity of the produced chimeric recombinant antigen with the sera of strongyloidiasis patients. The sensitivity and specificity of the indirect ELISA system, using the produced SsIR-Ss1a chimeric antigen, were found to be 93.94% (95% CI, 0.803 to 0.989) and 97.22% (95% CI, 0.921 to 0.992) respectively. Conclusions/Significance: The preliminary findings of this study suggest that the produced SsIR-Ss1a chimeric antigen shows promise in the diagnosis of human strongyloidiasis. However, these results are based on a limited panel of samples, and further research with a larger sample size is necessary to confirm its accuracy. The construct has potential as an antigen in the ELISA system for the serological diagnosis of this neglected parasitic infection, but additional validation is required. Author summary: In our study, we aimed to improve the diagnosis of strongyloidiasis, a parasitic infection that is often difficult to detect with current methods. Traditional parasitological and molecular techniques have limitations in sensitivity, making it challenging to accurately diagnose this condition. To address this, we designed a new diagnostic tool using a chimeric recombinant antigen, combining two specific antigens from the parasite Strongyloides stercoralis. We used advanced bioinformatics to select the most immunogenic regions of these antigens, ensuring they did not overlap with other parasite proteins. This chimeric antigen was then produced and tested for its diagnostic performance in an ELISA system. Our results showed that the new chimeric antigen is both soluble and highly antigenic; meaning it effectively triggers an immune response. When tested with sera samples from patients with strongyloidiasis, the ELISA system using our chimeric antigen demonstrated high sensitivity (93.94%) and specificity (97.22%), indicating it could accurately identify infected individuals. These findings are promising, suggesting that our chimeric antigen could be a valuable tool for diagnosing strongyloidiasis. However, further research with a larger sample size is needed to confirm its effectiveness. If validated, this new diagnostic approach could significantly improve the detection and management of this neglected parasitic infection, benefiting both patients and healthcare providers. [ABSTRACT FROM AUTHOR]

Background. Toxocariasis is an important zoonotic infection, especially in tropical areas. One of the significant challenges in the serodiagnosis of human toxocariasis is the cross-reaction of Toxocara antigens with other parasites due to their relatively similar glycan structures. Removing the glycan structure from Toxocara excretory-secretory (TES) antigens may increase the efficacy of these antigens in the diagnosis of toxocariasis. The current study aimed to assess the efficacy of deglycosylated Toxocara cati excretory-secretory (dTES) antigens for the serodiagnosis of human toxocariasis. Methods. Toxocara ES antigens were prepared from T. cati second-stage larvae and deglycosylated using sodium hydroxide (NaOH). The TES antigens, along with the dTES antigens, were used in an ELISA as well as a western blotting system for the detection of anti-Toxocara antibodies. Sera samples collected from 30 confirmed cases of toxocariasis, 30 patients with other diseases, and 30 healthy subjects were evaluated by both systems. Results. The sensitivity of TES and dTES ELISA for the diagnosis of human toxocariasis was 96.67% (95% CI = 82.78–99.92) and 93.33% (95% CI = 77.93–99.18), respectively, while the specificity of dTES (88.33%; 95% CI = 77.43–95.18) increased significantly compared to the TES (80.00%; 95% CI = 67.67–89.22). The sensitivity of both antigens was 100% (95% CI = 88.43–100) by the western blotting system. Moreover, the specificity of TES and dTES antigens was 95% (95% CI = 86.08–98.96) and 98.33% (95% CI = 91.06–99.96), respectively, when using the western blotting system. Conclusion. Results of the current study indicate that the chemical removal of the glycan epitopes of T. cati ES antigens significantly reduces cross-reactivity rates with other parasitic infections. Considering the findings of the present study, the dTES antigens seem to be suitable antigens for the serodiagnosis of human toxocariasis. [ABSTRACT FROM AUTHOR]

The development of suitable serological tests for the diagnosis of CE is still necessary. This study aimed to evaluate the efficacy of ELISA in the diagnosis of human cystic echinococcosis (CE), using parasite protoscolices antigens. Liver hydatid cysts were isolated from sheep infected with hydatid cysts and the protoscolices were isolated from the hydatid cyst fluid. Protoscolices crude antigen was prepared by mechanical disruption, plus freeze-thawing and sonication methods. Thirty sera samples of confirmed hydatid cyst patients, 30 samples of healthy individuals, and 30 samples of people with other infections were collected and the samples were evaluated in an ELISA system, using the crude protoscolices antigen. The sera samples were also simultaneously evaluated by antigen B-ELISA. The estimated value of sensitivity and specificity for the ELISA, using the crude protoscolices antigens, was 93.3% (95% CI: 76.4–98.8%) and 90% (95% CI: 78.8–95.8%), respectively. These values were 86.6 (95% CI: 68.3–95.6) and 91 (95% CI: 80.81–96.9) for the antigen-B based ELISA. Antigens prepared from protoscolices of hydatid cyst are suitable candidates for the serologic diagnosis of human CE. Further studies are needed to identify a single specific antigen among the protoscolices antigens to improve the diagnostic performance of these antigens. [ABSTRACT FROM AUTHOR]