{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,7]],"date-time":"2026-02-07T02:56:58Z","timestamp":1770433018508,"version":"3.49.0"},"reference-count":17,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2026,2,6]],"date-time":"2026-02-06T00:00:00Z","timestamp":1770336000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Antibodies"],"abstract":"<jats:p>Background\/Objectives: Allergic features of anisakiasis, caused by ingestion of third-stage larvae of Anisakis simplex via raw or undercooked fish, manifest clinically as acute gastroallergic anisakiasis (GAA) or chronic urticaria with Anisakis sensitization (CU+). Differentiating these clinical phenotypes remains challenging. This study aimed to evaluate the maturation and avidity of specific antibodies (IgE, IgG4, IgG, and IgA) as biomarkers for discriminating between acute and chronic forms of anisakiasis. Methods: A prospective cohort of 65 patients from Madrid, Spain, was classified into three groups: GAA (n = 22), CU+ (n = 22), and chronic urticaria without sensitization (CU\u2212, n = 21). Serum samples were analyzed for antigen-specific immunoglobulins using ELISA and Western blot. Avidity indices (AIs) were quantified through urea dissociation assays. Statistical comparisons and correlation analyses were performed to associate antibody avidity with clinical phenotype and demographic variables. Results: GAA patients exhibited significantly lower IgE avidity indices compared to CU+ individuals (mean AI: 79.9% vs. 88.5%), indicating a less mature IgE response during acute infection. Conversely, IgG4 and IgG avidity were elevated in GAA relative to CU+, reflecting an active but transient immune response. IgA antibodies were detected in both groups, although avidity differences lacked discriminatory capacity. No sex- or age-related differences in antibody avidity were observed. Longitudinal follow-up of GAA patients demonstrated an increase in IgE avidity over time. Conclusions: Quantitative assessment of antibody avidity, particularly for IgE and IgG4, enhances understanding of A. simplex immunopathogenesis and serves as a valuable biomarker for distinguishing acute from chronic clinical presentations. These findings support the use of avidity indices in the diagnosis, staging, and clinical management of anisakiasis.<\/jats:p>","DOI":"10.3390\/antib15010013","type":"journal-article","created":{"date-parts":[[2026,2,6]],"date-time":"2026-02-06T13:33:50Z","timestamp":1770384830000},"page":"13","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Antibody Avidity Profiles as Diagnostic Biomarkers in Differentiating Acute and Chronic Anisakis simplex\u2014Related Allergic Diseases"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0306-8399","authenticated-orcid":false,"given":"Juan","family":"Gonz\u00e1lez-Fern\u00e1ndez","sequence":"first","affiliation":[{"name":"Departamento de Microbiolog\u00eda y Parasitolog\u00eda, Facultad de Farmacia, Universidad Complutense de Madrid, 28040 Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-6709-2305","authenticated-orcid":false,"given":"Laura","family":"Ullate","sequence":"additional","affiliation":[{"name":"Departamento de Microbiolog\u00eda y Parasitolog\u00eda, Facultad de Farmacia, Universidad Complutense de Madrid, 28040 Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6490-9297","authenticated-orcid":false,"given":"Marta","family":"Rodero","sequence":"additional","affiliation":[{"name":"Departamento de Microbiolog\u00eda y Parasitolog\u00eda, Facultad de Farmacia, Universidad Complutense de Madrid, 28040 Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alvaro","family":"Daschner","sequence":"additional","affiliation":[{"name":"Instituto de Investigaci\u00f3n Sanitaria (IIS)\u2014Servicio de Alergia, Hospital Universitario de La Princesa, 28006 Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7948-9889","authenticated-orcid":false,"given":"Carmen","family":"Cu\u00e9llar","sequence":"additional","affiliation":[{"name":"Instituto de Investigaci\u00f3n Sanitaria (IIS)\u2014Servicio de Alergia, Hospital Universitario de La Princesa, 28006 Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,2,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1095","DOI":"10.1046\/j.1365-2222.1999.00574.x","article-title":"Human immunoglobulin isotype profiles produced in response to antigens recognized by monoclonal antibodies specific to Anisakis simplex","volume":"29","author":"Lorenzo","year":"1999","journal-title":"Clin. Exp. Allergy"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"20","DOI":"10.1016\/S1471-4922(01)02152-3","article-title":"Anisakis simplex: Dangerous\u2014dead and alive?","volume":"18","author":"Audicana","year":"2002","journal-title":"Trends Parasitol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"9","DOI":"10.1016\/j.pt.2011.10.001","article-title":"The Anisakis allergy debate: Does an evolutionary approach help?","volume":"28","author":"Daschner","year":"2012","journal-title":"Trends Parasitol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"111602","DOI":"10.1016\/j.intimp.2024.111602","article-title":"Serum IgA contributes to the comprehension of Anisakis simplex associated chronic urticaria","volume":"129","author":"Ullate","year":"2024","journal-title":"Int. Immunopharmacol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"164","DOI":"10.1002\/jcla.20126","article-title":"A serological follow-up of toxocariasis patients after chemotherapy based on the detection of IgG, IgA, and IgE antibodies by enzyme-linked immunosorbent assay","volume":"20","author":"Elefant","year":"2006","journal-title":"J. Clin. Lab. Anal."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Menu, E., Kopec, L., Luciani, L., Legrand, S., and L\u2019Ollivier, C. (2021). Measurement of the IgG Avidity Index in the Diagnosis of Clinical Toxocariasis Patients. Pathogens, 10.","DOI":"10.3390\/pathogens10091086"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"108236","DOI":"10.1016\/j.exppara.2022.108236","article-title":"Study of IgG avidity and the level of specific IgA antibodies and their significance in the diagnosis of human toxocarosis","volume":"236\u2013237","author":"Kaneva","year":"2022","journal-title":"Exp. Parasitol."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Tork, M., Sadeghi, M., Asgarian-Omran, H., Basirpour, B., Ahmadi, S., Ghasemzadeh, F., Sarvi, S., Gholami, S., Hosseini, S.A., and Daryani, A. (2025). Assessment of simultaneous IgM, IgG avidity, and IgA testing in diagnosis of acute toxoplasmosis in pregnant women: A systematic review and meta-analysis study. BMC Pregnancy Childbirth, 25.","DOI":"10.1186\/s12884-025-07580-6"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"106781","DOI":"10.1155\/2013\/106781","article-title":"Avidity Studies in Anisakis simplex-Associated Allergic Diseases","volume":"2013","author":"Cuellar","year":"2013","journal-title":"J. Allergy"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"736","DOI":"10.1093\/infdis\/159.4.736","article-title":"Recent primary Toxoplasma infection indicated by a low avidity of specific IgG","volume":"159","author":"Hedman","year":"1989","journal-title":"J. Infect. Dis."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"802","DOI":"10.1128\/CDLI.8.4.802-805.2001","article-title":"Antibody maturation in Trypanosoma cruzi-infected rats","volume":"8","author":"Marcipar","year":"2001","journal-title":"Clin. Diagn. Lab. Immunol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"809","DOI":"10.1080\/00365540110027321","article-title":"Avidity determination of Borrelia burgdorferi-specific IgG antibodies in Lyme disease","volume":"33","author":"Rauer","year":"2001","journal-title":"Scand. J. Infect. Dis."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"203","DOI":"10.1111\/j.1365-2249.2005.02981.x","article-title":"The time course of biological and immunochemical allergy states induced by Anisakis simplex larvae in rats","volume":"143","author":"Cho","year":"2006","journal-title":"Clin. Exp. Immunol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"725","DOI":"10.1017\/S0031182008004368","article-title":"Follow-up of antibody avidity in BALB\/c mice infected with Toxocara canis","volume":"135","author":"Fenoy","year":"2008","journal-title":"Parasitology"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"504","DOI":"10.1111\/j.1469-0691.2006.01444.x","article-title":"Toxoplasma gondii infection in pregnancy: Opportunities and pitfalls of serological diagnosis","volume":"12","author":"Sensini","year":"2006","journal-title":"Clin. Microbiol. Infect."},{"key":"ref_16","first-page":"824","article-title":"Validation of an in-house assay for cytomegalovirus immunoglobulin G (CMV IgG) avidity and relationship of avidity to CMV IgM levels","volume":"9","author":"Prince","year":"2002","journal-title":"Clin. Diagn. Lab. Immunol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"e43","DOI":"10.1590\/s1678-9946202466043","article-title":"Evaluation of different cut-off points for IgG avidity and IgM in the diagnosis of acute toxoplasmosis in pregnant women participating in a congenital toxoplasmosis screening program","volume":"66","author":"Laguardia","year":"2024","journal-title":"Rev. Inst. Med. Trop. Sao Paulo"}],"container-title":["Antibodies"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4468\/15\/1\/13\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,2,6]],"date-time":"2026-02-06T13:46:02Z","timestamp":1770385562000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4468\/15\/1\/13"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,2,6]]},"references-count":17,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2026,2]]}},"alternative-id":["antib15010013"],"URL":"https:\/\/doi.org\/10.3390\/antib15010013","relation":{},"ISSN":["2073-4468"],"issn-type":[{"value":"2073-4468","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,2,6]]}}}