title: Application of salivary antibody immunoassays for the detection of incident infections with Norwalk virus in a group of volunteers.
abstract: Norovirus infection is the most common cause of acute gastroenteritis in developed countries. Developing an assay based on a non-invasive biomarker for detecting incident norovirus infections could improve disease surveillance and epidemiological investigations. This project involved analysis of IgA and IgG norovirus-specific antibody responses in saliva samples from a Norwalk virus (Genogroup I, genotype 1 norovirus) challenge study involving infected and symptomatic, and non-infected asymptomatic individuals. Saliva was collected at the challenge, and two weeks and 40 days post-challenge. Samples were analyzed using the Luminex fluorometric and Meso Scale Discovery (MSD) electrochemiluminescence immunoassays. Recombinant P domains of Norwalk virus capsid protein, as well as similar recombinant proteins of two genogroup II noroviruses (VA387 and VA207) were used as antigens. Immunoconversions were defined as >4-fold increase in antibody responses to the norovirus antigens. Various sample pre-treatment options, buffers, saliva dilution ratios, and data adjustment approaches to control for sample-to-sample variability in saliva composition were compared using the Luminex assay. The results suggest that adjusting responses to the norovirus antigens for responses to the protein purification tag, glutathione-S-transferase (GST), significantly improved the odds of producing a correct immunoconversion test result. IgG-based tests were more accurate compared to IgA-based tests. At optimal conditions, both Luminex and MSD assays for Norwalk-specific IgG antibodies correctly identified all infected and non-infected individuals. There was no evidence of cross-reactivity of anti-Norwalk virus antibodies with genogroup II noroviruses. These results suggest that salivary antibody responses can be used for the detection of incident infections with Norwalk virus in prospective surveys.
authors.affiliation: National Exposure Research Laboratory, US Environmental Protection Agency, Cincinnati, OH, USA.
authors.forename: Shannon M
authors.initials: SM
authors.lastname: Griffin
authors.affiliation: National Health and Environmental Effects Research Laboratory, US EPA, 109T.W. Alexander Drive, MD 58C, Research Triangle Park, NC 27711, USA.
authors.forename: Reagan R
authors.initials: RR
authors.lastname: Converse
authors.affiliation: Rollins School of Public Health, Emory University, Atlanta, GA, USA.
authors.forename: Juan S
authors.initials: JS
authors.lastname: Leon
authors.affiliation: National Health and Environmental Effects Research Laboratory, US EPA, 109T.W. Alexander Drive, MD 58C, Research Triangle Park, NC 27711, USA.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Wade
authors.affiliation: Division of Infectious Diseases, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Xi
authors.initials: X
authors.lastname: Jiang
authors.affiliation: Rollins School of Public Health, Emory University, Atlanta, GA, USA.
authors.forename: Christine L
authors.initials: CL
authors.lastname: Moe
authors.affiliation: National Health and Environmental Effects Research Laboratory, US EPA, 109T.W. Alexander Drive, MD 58C, Research Triangle Park, NC 27711, USA. Electronic address: andegorov@gmail.com.
authors.forename: Andrey I
authors.initials: AI
authors.lastname: Egorov
mesh_terms: D000914:Antibodies, Viral / Q000276:immunology*; D017250:Caliciviridae Infections / Q000175:diagnosis* / Q000276:immunology*; D015200:Fluoroimmunoassay / Q000379:methods*; D005759:Gastroenteritis / Q000175:diagnosis* / Q000276:immunology*; D064368:Healthy Volunteers; D006801:Humans; D007070:Immunoglobulin A / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D009663:Norwalk virus / Q000276:immunology*; D011446:Prospective Studies; D012463:Saliva / Q000276:immunology*; D012680:Sensitivity and Specificity
chemical_list: D000914:Antibodies, Viral; D007070:Immunoglobulin A; D007074:Immunoglobulin G
keywords: Immunoassay; Incident infection; Norovirus; Salivary antibody; Volunteer challenge study