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Evaluation of In-House Salivary IgG Antibody Assays for the Detection of Chronic Toxoplasma gondii and Helicobacter pylori Infections
Citation:
Styles, J., A. Egorov, R. Converse, E. Sams, AND T. Wade. Evaluation of In-House Salivary IgG Antibody Assays for the Detection of Chronic Toxoplasma gondii and Helicobacter pylori Infections. American Society of Microbiology Annual Meeting, San Francisco, California, June 20 - 24, 2019.
Impact/Purpose:
In-house salivary IgG assays may be a useful tool for epidemiologic surveillance of Helicobacter pylori and Toxoplasma gondii infections, although further development is required.
Description:
Background: Helicobacter pylori is a bacterium that infects approximately 30% of the US population. It is transmitted via the fecal-oral and oral-oral routes. Toxoplasma gondii is a protozoan parasite infecting approximately 10% of the US population. It is acquired mainly by ingesting environmental oocysts excreted by cats or consuming undercooked meat with infectious tissue cysts. Duodenal and gastric ulcers can be caused by H. pylori while chronic T. gondii infections are associated with psychiatric disorders. Salivary assays are potentially useful in population surveys of chronic infections with these pathogens due to the ease of use enabling self-sampling by participants. This study evaluated an in-house duplex Luminex assay for monitoring salivary IgG responses to these pathogens. Methods: Paired serum and saliva samples were collected cross-sectionally from 703 adults in the Durham-Chapel Hill, North Carolina area. Commercially available ELISA kits were used to test sera for anti-H. pylori (Micro Detect; Tustin, CA) and anti-T. gondii IgG (Viro-Immun Labor-Diagnostika; Oberursel, Germany) responses. Serum and saliva samples were also tested for IgG responses to these pathogens using in-house Luminex assays utilizing various antigens and assay conditions. Optimal assay specifications were determined via Receiver Operating Characteristic (ROC) analyses using serologic enzyme-linked immunosorbent assays (ELISAs) as a reference method. Sensitivity and specificity were estimated by minimizing sum of squares. Results: Based on ELISA results, seroprevalence of H. pylori and T. gondii in this study was 15.4% and 9.5% respectively. The in-house serum anti-H. pylori IgG assay using a lysed purified culture (Meridian Life Science; Memphis, TN) had a sensitivity of 89% and a specificity of 89% (Area Under the Curve, AUC 96%), while the serum anti-T. gondii IgG assay using a purified P30 protein from the same vendor had a sensitivity of 96% and a specificity of 87% (AUC 96%), compared to serological ELISA tests. The salivary H. pylori IgG assay had a sensitivity of 82% and a specificity of 85% (AUC 92%), while the T. gondii IgG salivary assay had a sensitivity of 77% and a specificity of 85% (AUC 89%), compared to serological ELISAs. Conclusion: After further optimization, in-house salivary IgG assays may become a useful tool for epidemiologic surveillance of these pathogens. This abstract does not represent EPA policy.